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RESEARCH Open Access
Compressive sensing image fusion in
heterogeneous sensor networks based
on shearlet and wavelet transform
Ying Tong1,2* and Jin Chen1,2*
Abstract
Heterogeneous image fusion is a technique of fusing images captured by different sensors into one image,
then the fused image will present more information than the original images. This paper studies the compressive
sensing image fusion algorithm and applies shearlet and wavelet transforms to represent the image sparsely. By
compressing the sampled coefficients of the original images, the computational complexity in the image fusion
process is reduced and the fusion efficiency is improved. We focus on the image fusion rules of compressive domain.
Image coefficients of different frequencies are compressed by various sampling rates and fused according to different
fusion rules. So an ideal fusion results can be obtained under a low sampling rate.
Keywords: Compressive sensing, Shearlet transform, Image fusion
1 Introduction
Heterogeneous sensor networks consist of multimodal
sensors [1, 2] such as radar, optical, infrared, and acoustic.
Infrared and visible image fusion in heterogeneous sensor
networks is a hot research topic in the field of image pro-
cessing [3–6]. The advantages of infrared and visible band
imaging complement each other. The fused image con-
tains two bands of information, which is widely used in
visual monitoring, industrial testing, and many other fields
[7, 8]. With the rapid improvement of image sensor pro-
duction, high resolution cameras can show images quite
clearly, but it is really a challenge to transmit and store so
huge amount of image data. So in this paper, the image
fusion algorithm based on compressive sensing domain is
proposed [9, 10], which can reduce the amount of data
storage and transmission and meanwhile lower the
complexity of computation. So the overall system data
processing efficiency can be improved.
2 Image sparse representation
The commonly used image sparse representation
transforms are wavelet, curvelet, contourlet, and so
on [11–13]. Shearlet transform is a new transform de-
veloped in recent years, which has more advantages
than wavelet transform in high-dimensional data
sparse representation, since it can express the singu-
larity of space geometry much better [14, 15]. So we
use shearlet transform and wavelet transform succes-
sively for image sparse representation. The advantage
of this method is that it can combine the advantages
of two kinds of multi-resolution analysis tools in
image processing [16, 17] and increase the sparsity of
the signals further, so we can use less data to
complete the image fusion efficiently.
The original images can be decomposed into high-
frequency coefficients and low-frequency coefficients
after shearlet transform. Then, the coefficients will be
processed by wavelet transform separately and four dif-
ferent frequency components of the coefficients can be
obtained (shown in Fig. 1). The sparsity of different
components also shows a big difference. Based on the
sparsity of various frequency components, the coeffi-
cients are sampled at different sampling rates. Image
sparse representation model is shown in Fig. 1.
The sparsity of the low-frequency coefficients is rela-
tively low, so it is of little significance to compress the
wavelet low-frequency coefficients of shearlet low-
frequency components ( LL). Therefore, the LL
* Correspondence: tongying2334@163.com; cjwoods@163.com
1Tianjin Key laboratory of Wireless Mobile Communications and Power
Transmission, Tianjin Normal University, Tianjin 300387, China
Full list of author information is available at the end of the article
© The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and
reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made.
Tong and Chen EURASIP Journal on Wireless Communications and Networking
 (2017) 2017:52 
DOI 10.1186/s13638-017-0837-z
components are not compressively sampled, but fused
directly. The wavelet low-frequency coefficients of shear-
let high-frequency components (LH) and the wavelet
high-frequency coefficients of shearlet low-frequency
components (HL) are sparser than LL components, so
they can be compressively sampled and fused in the
compressive sensing domain. The highest frequency
components are wavelet high-frequency coefficients of
shearlet high-frequency components (HH), which have
the largest sparsity, so they can be compressively sam-
pled with a lower sampling rate than the HL and LH
components.
3 Image fusion rules
The image fusion rule determines the retention degree
of each original image in the fused image. In this paper,
the fusion rules are designed for the components of dif-
ferent frequency coefficients after compression.
The low-frequency coefficients (LL components) rep-
resent the approximation of the original image. The
brightness and contrast of the fused image are mainly
determined by the fusion rules of the LL components.
The imaging effects of infrared and visible cameras are
quiet different, because of their different imaging
principle. In some environments which are favorable for
visible light imaging, the visible image has large amount
of information and the texture is rich while in the dark,
foggy environments, the infrared imaging has its advan-
tages of clear, stable and can indicate thermal informa-
tion. For this part of the low-frequency coefficients, the
local spatial frequency-based weighted fusion rule will
be suitable, that is, the image with rich local spatial in-
formation will be set to a larger weight in the fusion
process. Formula (1) shows the definition of local spatial
frequency.
RF x; yð Þ ¼
ﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃX
m∈W ;n∈W
f xþm; yþ nð Þ−f xþm; y−1þ nð Þð Þ2
s
= w wð Þ
ð1Þ
CF x; yð Þ ¼
ﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃX
m∈W ;n∈W
f xþm; yþ nð Þ−f x−1þm; yþ nð Þð Þ2
s
= w wð Þ
SF x; yð Þ ¼
ﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃﬃ
RF x; yð Þ2 þ CF x; yð Þ2
q
In the above formula, RF (x, y) represents the local
(in the window with the dimension of W ×W)) spatial
frequency of the pixel (x, y) in row direction, and CF
(x, y) represents the local spatial frequency in column
direction; SF (x, y) is the local spatial frequency of
the point (x, y).
The LH and HL image components correspond to the
boundary of the smooth part of the image. In order to
highlight the feature of the target region and ensure that
the local region with large energy can be clearly reflected
in the fused image, the fusion rule will be based on the
regional energy feature. The regional energy feature is
defined as follows:
E x; yð Þ ¼
X
m∈M;n∈N
f xþm; yþ nð Þð Þ2 ð2Þ
The fusion rule of the LH and HL components pays
much attention to retain the coefficients with large
regional energy, so it is defined as follows:
Fig. 1 The original image sparse representation model
Tong and Chen EURASIP Journal on Wireless Communications and Networking  (2017) 2017:52 Page 2 of 5
F x; yð Þ ¼ I x; yð Þ if EI x; yð Þ > EV x; yð Þ
V x; yð Þ if EV x; yð Þ > EI x; yð Þ

ð3Þ
The HH components are the highest frequency com-
ponents after decomposition, corresponding to the
image detail textures. So the fusion rule of these parts
will adopt the absolute maximum fusion rule so that the
fused image can keep rich texture information.
4 Experiment and data analysis
In order to verify the fusion effects of our algorithm,
two sets of infrared and visible images are selected to
perform experiments at different compressive sampling
rates. One group is the cup images taken close-up in-
door, and the other is the outdoor scene images taken in
the yard. Each set of images consists of strictly registered
infrared and visible images, and all the images are of the
size of 512 × 512 (shown in Fig. 2).
Figures 3 and 4 are composed of six graphs, in which
Fig. 3a and Fig. 4a are the fusion of the two original images
after shearlet and wavelet transforms without compressive
sampling, and the coefficients of each scale are fused ac-
cording to the rule of absolute maximum. Figure 3b and
Fig. 4b are the fused effects according to the fusion rule
proposed in the paper without compressive sampling. The
other figures in Figs. 3 and 4 use the principle of compres-
sive sensing to compress all the coefficients except LL com-
ponents. Among them, the coefficients of each layer in Fig.
3c and Fig. 4c are compressed to 300 pixels in each row
and each column, that is, the coefficients sampling rate is
58.6%; the coefficients of each layer in Fig. 3d and Fig. 4d
are compressed to 200 pixels in each row and each column,
the coefficients sampling rate is 39.0% while the coefficients
of each layer in Fig. 3e and Fig. 4e are compressed to 100
pixels in each row and each column, coefficient sampling
rate is 19.5%; Fig. 3f and Fig. 4f use different sampling rates
to compress HL, LH, and HH components. The sampling
rate of HL and LH components is 39.0%, while the sam-
pling rate of HH components is 19.5%, just the same as Fig.
3e and Fig. 4e.
From the subjective perception of the human eyes, the
fusion rule proposed in this paper can take into account
the advantages of two-band imaging, not only retains
the rich texture information of visible light images but
also the thermal information of infrared images, and the
image brightness is uniform.
While the sampling rates decrease gradually, the quality of
the fusion image shows a decreasing trend, which is mainly
Fig. 2 The original images for fusion, a Infrared image of Cup, b Visible image of Cup, c Infrared image of Yard d Visible image of Yard
Tong and Chen EURASIP Journal on Wireless Communications and Networking  (2017) 2017:52 Page 3 of 5
manifested in the blurring of the texture detail. In particular,
the clarity of Fig. 3e and Fig. 4e drops a lot compared with
Fig. 3c, d and Fig. 4c, d. But there is little difference between
Fig. 3f, Fig. 4f and Fig. 3d, Fig. 4d because the sampling rate
of Fig. f is different for different frequency components.
Piella method is an authoritative fusion image evalu-
ation method. Q, QW, and QE are used to evaluate the
image fusion performance [18]. Q is the fusion quality
index, QW is the weighted fusion quality index, and QE
is the edge-dependent fusion quality index. The range of
the index is in [−1, 1], the closer to 1, the better the fu-
sion effect. We use the Piella parameters to evaluate the
performance of our algorithm. The results are shown in
Table 1.
It can be concluded from the Piella parameters that
the fusion method proposed in this paper has good
Fig. 3 The fusion effects of cup a The absolute maximum fusion rule, sampling rate =100%, b The proposed fusion rule, sampling rate =100%,
c The proposed fusion rule, sampling rate =58.6%, d The proposed fusion rule, sampling rate =39.0%, e The proposed fusion rule, sampling
rate =19.5%, f The proposed fusion rule, different sampling rate for different components
Fig. 4 The fusion effects of yard a The absolute maximum fusion rule, sampling rate =100%, b The proposed fusion rule, sampling rate =100%,
c The proposed fusion rule, sampling rate =58.6%, d The proposed fusion rule, sampling rate =39.0%, e The proposed fusion rule, sampling
rate =19.5%, f The proposed fusion rule, different sampling rate for different components
Tong and Chen EURASIP Journal on Wireless Communications and Networking  (2017) 2017:52 Page 4 of 5
image fusion effects, especially in the edge processing of
the fused images. With the decrease of the image com-
pressive rates, the image fusion effects decrease signifi-
cantly, which is consistent with the subjective feelings of
human eyes. The evaluation parameters of Fig. e vary a
lot with that of Fig. d, since the sampling rate of Fig. e is
quite low. Figure f uses different sampling rates for
different frequency components, and its evaluation result
is very close to Fig. d. So it can be explained that using
different sampling rates and fusion rules for different
frequency components is a good balance between fusion
effects and image compressive ratio.
5 Conclusions
An image fusion algorithm in heterogeneous sensor net-
works of compressive sensing domain is proposed.
Shearlet transform and wavelet transform are used suc-
cessively to sparse represent the infrared and visible im-
ages, which can increase the signal sparsity obviously.
Experiments show that the proposed algorithm can
achieve a good balance between the fusion effects and
the amount of data processing, because different sam-
pling rates and fusion rules are applied to different
frequency components of coefficients.
Acknowledgements
The authors would like to thank Tianjin Key Laboratory of Wireless Mobile
Communications and Power Transmission for their support.
Funding
The authors would like to thank Tianjin Edge Technology and Applied
Basic Research Project (14JCYBJC15800), Tianjin Normal University
Doctoral Foundation (52XB1603), and Tianjin Normal University
Application Development Foundation (52XK1601) in China for the
funding.
Availability of data and materials
The datasets supporting the conclusions of this article are included within
the article (and its additional file(s)).
Authors’ contributions
YT and JC conceived and designed the study. Both authors read and
approved the manuscript.
Competing interests
The authors declare that they have no competing interests.
Consent for publication
Not applicable
Ethics approval and consent to participate
Not applicable
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
Author details
1Tianjin Key laboratory of Wireless Mobile Communications and Power
Transmission, Tianjin Normal University, Tianjin 300387, China. 2College of
Electronic and Communication Engineering, Tianjin Normal University, Tianjin
300387, China.
Received: 21 February 2017 Accepted: 7 March 2017
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Table 1 Image fusion objective evaluation parameters of the
two sets of images
a b c d e f
Cup
Q 0.4893 0.5007 0.3323 0.2785 0.2010 0.2590
Qw 0.7054 0.7566 0.7195 0.6974 0.6495 0.6756
QE 0.1485 0.1939 0.1353 0.1148 0.0808 0.1071
Yard
Q 0.7637 0.7714 0.5933 0.4851 0.2984 0.4388
Qw 0.9163 0.9164 0.8720 0.8044 0.5839 0.7631
QE 0.4136 0.4225 0.3052 0.2248 0.0850 0.1838
Tong and Chen EURASIP Journal on Wireless Communications and Networking  (2017) 2017:52 Page 5 of 5


Compressive sensing image fusion in heterogeneous sensor networks based on shearlet and wavelet transform

Chemical composition and pharmacological activities of 
                  

The magic of money and the illusion of biofuels: toward an interdisciplinary understanding of technology

RESEARCH ARTICLE Open Access
Validation of general job satisfaction in the
Korean Labor and Income Panel Study
Shin Goo Park1* and Sang Hee Hwang2
Abstract
Background: The purpose of this study is to assess the validity and reliability of general job satisfaction (JS) in the
Korean Labor and Income Panel Study (KLIPS).
Methods: We used the data from the 17th wave (2014) of the nationwide KLIPS, which selected a representative
panel sample of Korean households and individuals aged 15 or older residing in urban areas. We included in this
study 7679 employed subjects (4529 males and 3150 females). The general JS instrument consisted of five items
rated on a scale from 1 (strongly disagree) to 5 (strongly agree). The general JS reliability was assessed using the
corrected item-total correlation and Cronbach’s alpha coefficient. The validity of general JS was assessed using
confirmatory factor analysis (CFA) and Pearson’s correlation.
Results: The corrected item-total correlations ranged from 0.736 to 0.837. Therefore, no items were removed.
Cronbach’s alpha for general JS was 0.925, indicating excellent internal consistency. The CFA of the general JS model
showed a good fit. Pearson’s correlation coefficients for convergent validity showed moderate or strong correlations.
Conclusion: The results obtained in our study confirm the validity and reliability of general JS.
Keywords: Job satisfaction, Reliability, Validity
Background
Job satisfaction is one of the most important factors in
the general quality of life, because it is connected closely
with working life [1]. There are many definitions of Job
Satisfaction (JS), so there are many assessment tools for
it. These tools have usually been divided into two types
of scale: specific and general scales. General scales are
used to estimate the respondent’s general overall feelings
about the job. These feelings are expected to predict im-
portant behavior, such as quitting or being absent [2].
Since 2002, the nationwide Korean Labor and Income
Panel Study (KLIPS) has been conducted annually to
collect information on general JS.). The questionnaire of
general JS was formulated by specialists based on the
Job Satisfaction Index [3]. It consisted of five items rated
on a scale from 1 (strongly disagree) to 5 (strongly
agree). The general JS of KLIPS has usually been ana-
lyzed to provide statistical data for labor policies, but it
has not been validated. Validity and reliability are the
two fundamental elements in evaluation of a measure-
ment instrument [4].
We investigated the validity and reliability of general JS
in the Korean Labor and Income Panel Study (KLIPS).
Methods
The reliability of the general JS scale was assessed using
the corrected item-total correlation and Cronbach’s alpha
coefficient. The validity was assessed using confirmatory
factor analysis (CFA) and Pearson’s correlation coefficients.
Data
This study used the data from the 17th wave (2014) of
the nationwide Korean Labor and Income Panel Study
(KLIPS), which selected a representative panel sample of
Korean households and individuals aged 15 or older res-
iding in urban areas. The first survey was launched in
1998, and data have been collected yearly since then.
The general JS data have been collected yearly since
2002. The survey was conducted using interviews by
trained staff. For the purpose of this study, we selected
those subjects having jobs (n = 7679).
* Correspondence: stressdr@naver.com
1Department of Occupational and Environmental Medicine, Inha University
Hospital, 27, Inhang-Ro, Jung-Gu, Incheon 22332, South Korea
Full list of author information is available at the end of the article
© The Author(s). 2017 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and
reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver
(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
Park and Hwang Annals of Occupational and Environmental Medicine  (2017) 29:10 
DOI 10.1186/s40557-017-0167-y
The survey was conducted by the Korean Labor
Institution and was approved by the ethical review board
of Statistics Korea. A written informed consent form
was obtained from each subject.
Instrument of general JS
The questionnaire of general JS consisted of five items
rated on a scale from 1 (strongly disagree) to 5 (strongly
agree). It was formulated by specialists based on the Job
Satisfaction Index [3]. The framing question is: “What do
you think of your current job? Answer by indicating the
extent to which you agree or disagree with each item.”
The five items are:
“I am satisfied with my current job” (item1),
“I am enthusiastic about my current job” (item2),
“I enjoy my current job” (item3),
“I’m feeling rewarded by my current job” (item4),
“I want to keep my current job unless there is a good
reason for changing” (item5).
Reliability
The reliability of the general JS scale was assessed using
the corrected item-total correlation and Cronbach’s
alpha coefficient.
We used the corrected item-total correlation to identify
the items that were less reliable and to remove them from
the general JS scale. Presumably, a low corrected item-total
correlation means that a specific item is less associated with
the overall scale and would have lower overall reliability [5].
A correlation coefficient of 0.40 or higher was used as a
cut-off for identifying the candidate items [6].
Cronbach’s alpha is the most widely used objective
measure of reliability. A threshold of 0.7 was considered
acceptable, a value >0.8 good, and a value >0.9 to indi-
cate excellent internal consistency [7].
Validity
Construct validity refers to the extent to which a test
measures the construct it is supposed to measure [8]. A
commonly used method to investigate construct validity
is confirmatory factor analysis (CFA) [9, 10]. CFA is used
when researchers have prior knowledge of latent (under-
lying) variables and seek to confirm factors that they
have found [11].
Since our general JS includes only one theoretical con-
struct, CFA was conducted in order to test whether the
one factor model construct was confirmed in this sample.
Several fit indices were selected for the CFA model, in-
cluding the Root mean Square Error of Approximation
(RMSEA), the Comparative Fit Index (CFI) and the
Tucker-Lewis Index (TLI). Since the overall χ2 fit index is
greatly influenced by the sample size, tending to over-reject
models with a large sample size, this index was not used
when drawing conclusions [12]. For CFI and TLI, a thresh-
old value > 0.9 was considered a good fit [13].
For the RMSEA, on the other hand, a value <0.06 was
considered as a good fit, a value <0.08 was considered
as an acceptable fit and a value >0.1 led to rejection of
the model [14].
Convergent validity was used to assess the construct
validity. The convergent validity was evaluated with the
Pearson’s correlation coefficients for the theoretically
correlated construct (one item general JS). The following
question was used to assess the one item JS: “Overall,
how satisfied are you with your present job?” The an-
swer is assessed using a 5-point Likert scale that ranged
from 1 (very dissatisfied) to 5 (very satisfied). Correla-
tions <0.3 were considered negligible, a value between
0.3 and 0.5 as moderate and a value >0.5 as strong [15].
Statistical analysis
All analyses were performed with SPSS (IBM Corp. Re-
leased 2010. IBM SPSS Statistics for Windows, Version
19.0. Armonk, NY: IBM Corp.).
The reliability of the general JS was assessed using the
corrected item-total correlation and Cronbach’s alpha
coefficient.
We examined validity of the general JS using CFA and
Pearson’s correlations. We evaluated the Pearson’s corre-
lations of our scale (five-items) with a one item scale for
convergent validity.
We used multiple goodness of fit tests to test the one
factor model, including the Root Mean Square Error of
Approximation (RMSEA), the Comparative Fit Index
(CFI) and the Tucker-Lewis Index (TLI). We used
AMOS17 for CFA.
Results
Subject characteristics are presented in Table 1. The
total number of subjects is 7679 (male 59%, female 41%).
The age group is the most frequent in the forties
(26.1%). The occupation is the most frequent in the pro-
fessionals (19.2%) (Table 1).
The corrected item-total correlations ranged from
0.736 to 0.837. Therefore, no items were removed. The
Cronbach’s alpha for general JS equals 0.925, indicating
excellent internal consistency of the measure (Table 2).
The CFA of the general JS model showed good con-
struct validity, with the observed data fitting well with the
theoretical model. The CFI, TLI and RMSEA (0.995, 0.990
and 0.063, respectively), indicated a good fit (Table 3).
The Pearson’s correlation of the five-item scale with
the one-item scale of JS ranged from 0.477 to 0.607,
indicating moderate or strong correlations of the
measure (Table 4).
Park and Hwang Annals of Occupational and Environmental Medicine  (2017) 29:10 Page 2 of 4
Discussion
This study is the first to investigate the reliability and val-
idity of the general JS in KLIPS. There are many defini-
tions of general JS. Locke suggested that general JS is the
pleasant sentiment derived from the perception (cogni-
tion) that the professional activity performed allows one’s
personal needs and values linked to the job (behavior) to
be satisfied and one’s goals to be achieved [16]. According
to Spector, the general JS is the way people “feel” about
their job and the aspects characterizing it [17].
The general scales of JS ask the respondent to combine
his or her reactions to various aspects of the job into a
single integrated response. They assume that some sort of
processing takes place and ask for its end product. During
this process, the respondent may incorporate other
aspects not measured in the facet scales or items [2].
There are various instruments to assess general JS: the
job satisfaction index (18 items) of Brayfield and Rothe
(1951), Minnesota Satisfaction questionnaire (20 items)
of Weiss, Dawis, Engl, and Lofquist (1967), the overall
measure (five-items) of Hackman and Oldham (1975),
the Facet-free Job Satisfaction (five-items) of Quinn and
Staines (1979), the Michigan Organizational Assessment
Questionnaire (MOAQ) (3 items) of Cammann, Fichman,
Jenkins, and Klesh (1979), Job in General (JIG) (18 items)
of Ironson et al. [4, 17].
Although they can be classified differently according
to the researchers, criterion validity was usually used
when a gold standard is available. Content validity and
construct validity were usually used when a gold standard
is lacking, as in the case of our study [18].
Content validity is a qualitative type of validity, where
the domain of the concept is made clear and the analyst
judges whether the measures fully represent the domain
[19]. Because there is no statistical test to determine
whether a measure adequately covers a content area or
adequately represents a construct, the content validity
usually depends on the judgment of experts in the field
[20]. The items of general JS in this study were formu-
lated by experts by considering the Korean situation
based on the Job Satisfaction Index [4].
Construct validity forms an essential part of evaluating
validity. Our study used CFA and Pearson’s correlation
to assess the construct validity. The fit indices of the one
factor model showed a good fit in the CFA of our study.
Two types of assessment of general JS have been con-
ducted annually in KLIPS, the five-item scale and one
item scale. The Pearson’s correlation of the five-item
scale with the one item scale were used to assess the
convergent validity. The result showed moderate or
strong correlations.
The main procedures for estimating internal consistency
among a number of different questions that are supposed
to reflect the same concept are the corrected item-total
Table 1 Characteristics of respondents
Variables Number Percent
Total 7679
Gender
Male 4529 59.0
Female 3150 41.0
Age
≤ 29 614 8.0
30–39 1756 22.9
40–49 2003 26.1
50–59 1825 23.8
≥ 60 1481 19.3
Occupation
Managers 104 1.4
Professionals 1466 19.2
Clerical Support Workers 1105 14.5
Services Workers 805 10.5
Sales Workers 888 11.6
Skilled Agricultural, Forestry and Fishery Workers 589 7.7
Craft and Related Trades Workers 831 10.9
Plant and Machine Operators and Assemblers 913 12.0
Elementary Occupations 939 12.3
Table 2 Corrected item-total correlations and Cronbach’s alpha
Items Corrected item-total
correlation
Cronbach’s alpha
if Item deleted
Item 1 0.796 0.909
Item 2 0.812 0.906
Item 3 0.837 0.901
Item 4 0.837 0.901
Item 5 0.736 0.921
Cronbach’s alpha 0.925
Table 3 Goodness of Fit Indices
X2 df p TLI CFI RMSEA
155.614 5 0.000 0.990 0.995 0.063
df Degree of freedom, TLI Turker-Lewis Index, CFI Comparative Fit Index,
RMSEA Root Mean Error of Approximation
Table 4 Pearson’s correlation five- item scale with one-item
scale of general job satisfaction
Item Mean ± SD r P
Item 1 3.32 ± 0.755 0.607 0.000
Item 2 3.43 ± 0.755 0.518 0.000
Item 3 3.41 ± 0.739 0.567 0.000
Item 4 3.38 ± 0.757 0.549 0.000
Item 5 3.64 ± 0.765 0.477 0.000
Park and Hwang Annals of Occupational and Environmental Medicine  (2017) 29:10 Page 3 of 4
correlation and alpha reliability coefficients [6]. The cor-
rected item-total correlation was used to identify the items
that had less reliable signs and to remove them from the
general JS scale. The correlations are all >0.4 in our study,
so no items were removed.
The most common method of testing internal
consistency is the coefficient alpha [21]. The coeffi-
cient alpha is useful for estimating the reliability of the
item-specific variance in a unidimensional test [22].
The Cronbach’s alpha of 0.925 obtained in our study
showed excellent internal consistency. The occupations
held by participants in this study are broadly diverse
(Table 1). Therefore, this participant pool may be repre-
sentative of the general population having jobs in Korea.
The description of the qualitative study conducted in
the process of making the questionnaires was insuffi-
cient, because no validation was conducted when the
instrument of general JS was developed for the first time.
Although this study provided various validation pro-
cesses of general JS, other forms of reliability and validity
tests could be required to strengthen its applicability in
other populations.
Conclusion
The results observed in our study confirm the validity and
reliability of the general JS.
Abbreviations
CFA: Confirmatory factor analysis; JS: Job Satisfaction; KLIPS: Korean Labor
and Income Panel Study
Acknowledgement
All authors including myself have seen and approved manuscript.
Funding
Not applicable.
Availability of data and materials
The authors obtained the data set from the website for the KLIPS at the Korea
Labor Institute which is: http://www.kli.re.kr/klips/en/about/introduce.jsp
Authors’ contributions
SGP designed the study and analyzed the data. SHH participated in its
design and wrote the first draft of the manuscript. SGP and SHH revised
the draft paper. Both authors read and approved the final manuscript.
Competing interests
The authors declare that they have no competing interests.
Consent for publication
Not applicable.
Ethics approval and consent to participate
The survey was conducted by the Korean Labor Institution and was approved
by the ethical review board of Statistics Korea. A written informed consent form
was obtained from each subject.
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
Author details
1Department of Occupational and Environmental Medicine, Inha University
Hospital, 27, Inhang-Ro, Jung-Gu, Incheon 22332, South Korea. 2Department
of Dentistry, Keimyung University School of Medicine, 56, Dalseong-ro,
Jung-gu, Daegu 41931, South Korea.
Received: 2 November 2016 Accepted: 22 March 2017
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Park and Hwang Annals of Occupational and Environmental Medicine  (2017) 29:10 Page 4 of 4


Validation of general job satisfaction in the Korean Labor and Income Panel Study

Hotspots and key periods of Greenland climate change during the past six decades

Laurent Macron

Emilie Bollache

Nadjia Kachenoura

Alain De Cesare

Golmehr Ashrafpoor

Arshid Azarine

Alban Redheuil

Elie Mousseaux

POSTER PRESENTATION Open Access
Intraventricular ejection pressure gradient derived
from acceleration measurement by phase
contrast CMR as a new marker of left ventricular
contractility: feasibility study and preliminary
results in dilated cardiomyopathy
Laurent Macron1*, Emilie Bollache2, Nadjia Kachenoura2, Alain De Cesare2, Golmehr Ashrafpoor1, Arshid Azarine1,
Alban Redheuil1,2, Elie Mousseaux1,2
From 16th Annual SCMR Scientific Sessions
San Francisco, CA, USA. 31 January - 3 February 2013
Background
Intra-ventricular pressure gradient along the direction of
the outflow tract is generated by the impulse response of
the myocardial contraction. This spatial pressure gradient,
derived from the maximal acceleration estimates within
the left ventricular (LV) ejection flow, has been validated
in vitro by using MRI and was found strongly related to
the inotropic state of the LV as demonstrated in animal
and human echocardiographic studies. This acceleration
may be less dependant on load conditions than others LV
systolic function parameters, especially LV ejection
fraction (LVEF).
Aim: (1) to evaluate the feasibility of LV ejection flow
acceleration (Acc) estimates by spatial and temporal deri-
vative of velocities recorded by CMR using phase contrast
sequence, (2) to compare the acceleration values to LVEF
in patients with Dilated Cardiomyopathy (LVEF<50%) and
in control subjects.
Methods
Ten DCM patients (54±12 years, 60%men) and 14 age-
matched controls underwent CMR with cine sequences
to determine LV volumes and LVEF. Through plane
phase contrast acquisitions were obtained in breathhold
(TR = 7.5 ms, TE = 2.5 ms, 2 views per segment, tem-
poral resolution = 15 ms, FOV 32 to 36 cm with 126 x
256 matrix) at 2 consecutive levels, at the level of aortic
valve and 10 mm below through the LV outflow tract.
Total Acceleration (TotalAcc) and its two components,
Temporal (TempAcc) and Convective (ConvAcc) Accel-
eration were derived from velocities at phase contrast
sequence by using our home-made previously validated
semi-automatic software Art Fun.
Results
celeration measurement was feasible in all DCM and
controls. Overall, TempAcc (r=0.50, p=0.01) but not
ConvAcc (r=0.33, p=0.11) correlated with LVEF.
Nevetheless, TotalAcc was better correlated to LVEF
(r=0.71, p=0.0001) than TempAcc derived from velocities
obtained at the level of the aortic valve alone. Compared
to control, mean LVEF (30±13 vs. 66±6, p<0.0001) Tota-
lAcc (880±463 vs 1909±637 cm.s-2, p<0.001) and Tem-
pAcc (660±399 vs 1294±574 cm.s-2, p<0.01) but not
ConvAcc (706±508 vs 1044±747 cm.s-2, p=0.22) were sig-
nificantly lower in DCM.
Conclusions
This preliminary study demonstrated the feasibility of
LV ejection flow acceleration measurement derived
from velocities at phase contrast sequence by CMR.
TotalAcc is highly correlated to LVEF, better than Tem-
pAcc alone underlying the incremental value of
ConvAcc.
1Radiology, Cardiovascular Imaging Unit, HEGP, APHP, Paris, France
Full list of author information is available at the end of the article
Macron et al. Journal of Cardiovascular Magnetic
Resonance 2013, 15(Suppl 1):E6
http://www.jcmr-online.com/content/15/S1/E6
© 2013 Macron et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons
Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in
any medium, provided the original work is properly cited.
Funding
none.
Author details
1Radiology, Cardiovascular Imaging Unit, HEGP, APHP, Paris, France. 2LIF
INSERM U678, UPMC, Paris, France.
Published: 30 January 2013
doi:10.1186/1532-429X-15-S1-E6
Cite this article as: Macron et al.: Intraventricular ejection pressure
gradient derived from acceleration measurement by phase contrast
CMR as a new marker of left ventricular contractility: feasibility study
and preliminary results in dilated cardiomyopathy. Journal of
Cardiovascular Magnetic Resonance 2013 15(Suppl 1):E6.
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http://www.jcmr-online.com/content/15/S1/E6
Page 2 of 2


Intraventricular ejection pressure gradient derived from acceleration measurement by phase contrast CMR as a new marker of left ventricular contractility: feasibility study and preliminary results in dilated cardiomyopathy

3D Analysis of Porosity in a Ceramic Coating Using X-ray Microscopy

A mild thermomechanical process for the enzymatic conversion of radiata pine into fermentable sugars and lignin

Chinese Journal of Cancer  Chin J Cancer  (2017) 36:33 
DOI 10.1186/s40880-017-0200-0
EDITORIAL
The 150 most important questions 
in cancer research and clinical oncology series: 
questions 6–14
Edited by Chinese Journal of Cancer
Chinese Journal of Cancer*
Abstract 
To accelerate our endeavors to overcome cancer, Chinese Journal of Cancer has launched a program of publishing 150 
most important questions in cancer research and clinical oncology. In this article, nine more questions are presented 
as followed. Question 6. Why do nasopharyngeal carcinomas rarely metastasize to the brain? Question 7. Can distant 
spread of cancer cells be blocked by inhibiting the remodeling of high endothelial venules in the sentinel lymph 
node? Question 8. What sort of live-imaging techniques can be developed to directly observe the dynamic processes 
of metastasis? Question 9. How does chronic hepatitis prevent liver metastasis from colorectal cancer? Question 10. 
How many types of host cells contribute to forming the pre-metastatic niche in the lung favorable for metastasis? 
Question 11. Why do cancers rarely metastasize to the small bowel? Question 12. Why do glioblastomas rarely metas-
tasize outside the central nervous system? Question 13. Despite increased understanding of the molecular genetic 
events leading to the development and progression of high-grade gliomas, these tumors are the most therapeutically 
refractory among all human cancers. What then would be the most effective therapeutic approaches to treat what in 
essence can be regarded as a whole brain malignancy, since even a surgical resection of greater than 99% of tumor 
tissues is invariably associated with recurrence? Question 14. The blood–brain barrier (BBB) effectively limits a wide 
variety of potential therapeutic agents from reaching glioma cells widely dispersed in the brain. What therapeutic 
approaches can be used to breach the BBB and allow therapeutic agents to seek out and kill these tumor cells?
Keywords: Metastasis, Nasopharyngeal carcinoma, Colorectal cancer, Glioblastoma, High endothelial venules, 
Dynamic imaging, Pre-metastatic niche
© The Author(s) 2017. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License 
(http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, 
provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, 
and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/
publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
To accelerate our endeavors to overcome cancer, Chi-
nese Journal of Cancer has launched a program of pub-
lishing 150 most important questions in cancer research 
and clinical oncology [1], with the first five questions 
been published in the last two issues [2, 3]. In this article, 
questions 6–14 are selected and presented. Chinese Jour-
nal of Cancer is still open to collect more key questions 
in cancer research and clinical oncology. Please send 
us your thoughtful questions to Ms. Ji Ruan via email: 
ruanji@sysucc.org.cn.
Open Access
Chinese Journal of Cancer
*Correspondence: cjc@sysucc.org.cn 
Guangzhou, China. 
Page 2 of 5Chinese Journal of Cancer  Chin J Cancer  (2017) 36:33 
Question 6: Why do nasopharyngeal carcinomas 
rarely metastasize to the brain?
Background and implications
Of all head and neck cancers, nasopharyngeal carcinoma 
(NPC) has the highest metastasis rate. NPCs commonly 
metastasize to the lymph nodes, bone, liver, and lung. 
Given the close anatomic location of the nasopharynx to 
the brain, NPCs rarely metastasize to the brain. Deter-
mining the underlying molecular mechanism(s) may be 
very helpful for preventing brain metastases from other 
types of malignancies that are prone to spread to the 
brain.
Submitter
Chao-Nan (Miles) Qian.
Affiliation and email
Sun Yat-sen University Cancer Center, Guangzhou, 
Guangdong, P. R. China.
qianchn@sysucc.org.cn.
Question 7: Can distant spread of cancer cells 
be blocked by inhibiting the remodeling of high 
endothelial venules in the sentinel lymph node?
Background and implications
The sentinel lymph node is the most common first station 
in the metastatic cascade of carcinomas. The occurrence 
rate of distant metastasis is much higher in the patients 
with sentinel lymph node involvement than in those 
without sentinel lymph node metastasis. Therefore, the 
prognosis of cancer patients with sentinel lymph node 
involvement is usually poorer than that of the patients 
without sentinel lymph node involvement.
Our previous investigation has confirmed that primary 
tumor can induce vascular remodeling of high endothe-
lial venules (HEVs) in the sentinel lymph node even 
before the arrival of metastatic cancer cells. The normal 
physiological function of HEVs is to provide an extrava-
sation site for circulating naïve lymphocytes into the 
lymphoid tissue. Therefore, there are few or no red blood 
cells inside normal HEVs. The HEV remodeling induced 
by primary tumor is characterized by (1) enlargement 
of HEV lumen space; (2) reduced vessel wall thickness; 
(3) increased proliferation rate in the endothelial cells 
of HEV; and (4) increased red blood cell number inside 
the HEV lumen space. After cancer cell arrival, the meta-
static cancer nests can unlimitedly expand and eventu-
ally occupy the whole lymph node, while the remodeled 
HEVs become the mother vessels of the metastatic 
tumor accompanied by further remodeling of HEVs 
characterized by the loss of their normal immunological 
function for lymphocyte extravasation.
It is critical to clarify whether HEV remodeling in 
the sentinel lymph node could facilitate further spread 
of cancer cells from the sentinel lymph node to distant 
organs. If our speculation of the role of HEV remodeling 
in cancer metastasis is true, we could then block further 
spread of cancer cells from the sentinel lymph node by 
inhibiting the remodeling procedure of HEV. Answer-
ing this question would open a new door for us to block 
tumor metastasis and to significantly enhance cancer 
patient survival rate.
Submitter
Chao-Nan (Miles) Qian.
Affiliation and email
Sun Yat-sen University Cancer Center, Guangzhou, 
Guangdong, P. R. China.
qianchn@sysucc.org.cn.
Question 8: What sort of live‑imaging techniques 
can be developed to directly observe the dynamic 
processes of metastasis?
Background and implications
There is extensive work on investigating cancer metas-
tasis in animal models, particularly end-point data on 
established metastasis, with standard textbook mod-
els commonly describing classical sequential models 
of cancer metastasis (“late metastasis”). In recent years, 
these models are challenged by early metastasis models, 
as more data accrue on clonality of distant metastasis. 
While live-imaging animal models allow monitoring of 
these processes in animals, there is little direct data and 
observations on the dynamic processes of cancer metas-
tasis in humans, such as tumor cell intravasation, trans-
port through circulation, and extravasation at distant 
site. It would be important to establish live-imaging tech-
niques using innovative bioengineering approaches that 
would allow for sensitive detection and measurement of 
these processes. Such observations will certainly shed 
more light on the prevention of cancer metastasis.
Submitter
Min-Han Tan.
Affiliation and email
Institute of Bioengineering and Nanotechnology, Singa-
pore, Singapore.
minhan.tan@gmail.com.
Page 3 of 5Chinese Journal of Cancer  Chin J Cancer  (2017) 36:33 
Question 9: How does chronic hepatitis prevent 
liver metastasis from colorectal cancer?
Background and implications
Liver metastasis has been commonly seen in over 50% of 
patients with colorectal cancer. Chronic hepatitis caused 
by hepatitis B and C virus infection has been recognized 
as precancerous alteration for hepatocellular carcinoma. 
Interestingly, in colorectal cancer patient with chronic 
hepatitis, liver metastasis is rare. Obviously, chronic hep-
atitis prevents the manifestation of liver metastasis from 
colorectal cancer. Determining the underlying molecular 
mechanism(s) may be very helpful for preventing liver 
metastases from other types of malignancy that are prone 
to spread to the liver.
Submitter
Zhongguo (Roy) Zhou.
Affiliation and email
Sun Yat-sen University Cancer Center, Guangzhou, 
Guangdong, P. R. China.
zhouzhg@sysucc.org.cn.
Question 10: How many types of host cells 
contribute to forming the pre‑metastatic niche 
in the lung favorable for metastasis?
Background and implications
It is estimated that approximately 70% of cancer patients 
are died of tumor metastasis; among the patients who are 
succumbed to tumor metastasis, 20%–30% suffer from 
pulmonary metastasis. Numerous studies have dem-
onstrated that forming the pre-metastatic niche in the 
lung is a critical step in the progression of pulmonary 
metastasis. Several types of primary tumor displayed 
the potential ability to “prepare” a supportive and recep-
tive microenvironment in the lung for licensing circulat-
ing tumor cells (CTCs) colonization even before their 
arrival. Interestingly, compelling evidence showed that 
the formation of pre-metastatic niche was greatly associ-
ated with the interaction between tumor cells and host 
cells. In the stress of tumor-derived secreted factors and 
extracellular vesicles derived from the primary micro-
environment, the local lung stroma can be reformed to 
be a favorable secondary microenvironment for settle-
ment and progression of CTCs. The known cell types 
recruited to this altered microenvironment for metastasis 
include VEGFR1+  VLA-4+  bone marrow-derived cells, 
myeloid-derived suppressor cells, myeloid cells (Mac1+, 
CD11b+ CD68+ F4/80+, CD11b+/Mac1+, CD11b+/Gr-1+, 
CD11b+/Ly6Cmed/Ly6G+), monocytes (CD11b+  Ly6C+, 
IE2+, CD11b+/Gr1+), CD11b+  Ly6G+  Ly6C+  granu-
locytes, tumor-associated macrophages, regulatory T 
cells, VEGFR1+  VLA-4+  hematopoietic progenitor cells, 
endothelial progenitor cells, and neutrophils.
It is speculated that multiple cell types from the host 
are recruited to the pre-metastatic niche through a well-
organized procedure coordinated by the primary tumor. 
Before unveiling the crosstalk among different host cell 
types, an essential question would be as follows: have 
we identified all cell types in the pre-metastatic niche? 
Answering this question would be very useful for better 
understanding the formation of pre-metastatic niche in 
the lung and other organs.
Submitter
Chunlin Ou.
Affiliation and email
Central South University Cancer Research Institute, 
Changsha, Hunan, P. R. China.
ouchunlin@csu.edu.cn.
Question 11: Why do cancers rarely metastasize 
to the small bowel?
Background and implications
Of all the organs that may have cancer metastasis, the 
small bowel has the lowest metastasis rate. Determining 
the underlying molecular mechanism(s) through which 
the small bowel keeps away from metastasis may be very 
helpful for preventing metastases from different malig-
nancies that are prone to spread to specific organs.
Submitters
Xiaowen Wang, Dave Hoon.
Affiliation and email
Translational Molecular Medicine, John Wayne Cancer 
Institute, CA, USA.
xiaowen.wang@providence.org.
Question 12: Why do glioblastomas rarely 
metastasize outside the central nervous system?
Background and implication
Contrasting to extracranial cancers, glioblastomas are 
primarily formed in the brain and rarely metastasize out-
side the central nervous system even after neurosurgery 
which can destroy the blood–brain barrier. Actually, in 
rare circumstances, glioblastoma cells can spread to the 
lung, liver, bone, lymph node, and other distance organs. 
In animal experiments, glioblastoma cells can grow sub-
cutaneously in immuno-deficient mice. All these facts 
suggest that the brain microenvironment is not an indis-
pensable factor for the growth of glioblastoma cells. 
Other key limiting factors should exist to prevent the 
Page 4 of 5Chinese Journal of Cancer  Chin J Cancer  (2017) 36:33 
spreading or survival of glioblastoma cells outside the 
central nervous system. Determining these factors may 
be very helpful for understanding the mechanism of can-
cer metastases.
Submitter
Yong-Gao Mou.
Affiliation and email
Sun Yat-sen University Cancer Center, Guangzhou, 
China.
mouyg@sysucc.org.cn.
Question 13: Despite increased understanding 
of the molecular genetic events leading to the 
development and progression of high‑grade 
gliomas, these tumors are the most therapeutically 
refractory among all human cancers. What 
then would be the most effective therapeutic 
approaches to treat what in essence can be 
regarded as a whole brain malignancy, since even 
a surgical resection of greater than 99% of tumor 
tissues is invariably associated with recurrence?
Background and implications
The greatest single advance in the treatment of high-
grade gliomas, and more specifically, glioblastomas 
(GBM), over the past 30  years has been the addition of 
temozolomide (TMZ) to the postoperative radiother-
apy. This has resulted in only a 2.5-month increase in 
the median overall survival, to 14.5 months for patients 
receiving combination therapy, compared with 
12.1  months for those receiving radiotherapy alone. 
Clearly, new therapeutic approaches are needed to treat 
patients with GBMs.
What might these new therapeutic approaches consist 
of? First, it probably will entail a combination of new tar-
geted chemotherapeutic agents that will attack molecu-
lar checkpoints that drive GBMs to proliferate. Second, 
it might include immunotherapeutic approaches directed 
against molecular targets such as programmed death-1 
(PD-1) and tumor-specific antigens expressed on GBM 
cells. Third, it might include the use of oncolytic viruses 
such as genetically engineered herpes and adenoviruses 
that will be able to selectively target infiltrating tumor 
cells interspersed in so-called “normal” brain. Progress is 
being made with each of these approaches, but the chal-
lenge will be to effectively combine them with the current 
standard treatment to eradicate residual tumor cells that, 
up until this time, have evaded current chemoradiothera-
peutic approaches.
Submitter
Rolf F. Barth.
Affiliation and email
The Ohio State University, Columbus, OH, USA.
rolf.barth@osumc.edu.
Question 14: The blood–brain barrier (BBB) 
effectively limits a wide variety of potential 
therapeutic agents from reaching glioma cells 
widely dispersed in the brain. What therapeutic 
approaches can be used to breach the BBB 
and allow therapeutic agents to seek out and kill 
these tumor cells?
Background and implications
Curative treatment of glioblastomas requires effective 
delivery of a variety of therapeutic agents to glioma cells 
infiltrating the normal brain tissue. The BBB constitutes 
a significant barrier for the delivery of therapeutic agents 
with molecular weights greater than 200, making drug 
delivery to the brain more complex than to any other 
organ.
At the present time, a variety of approaches have been 
used to allow high molecular weight agents to traverse 
the BBB. These have included BBB disruption by ultra-
sound and hyperosmotic mannitol, the use of trans-
porter carriers such as insulin-like growth factor-1 and 
novel brain-penetrating peptides such as ANG4043 
that can be linked to therapeutic agents such as drug 
bioconjugates, and the direct intracerebral administra-
tion of therapeutic agents to the site of infiltrating gli-
oma cells, completely bypassing the BBB. Each of these 
approaches are currently being evaluated, and hopefully 
one or more of them, combined with new therapeutic 
agents as described in the previous question, will be 
able to selectively target residual proliferating tumor 
cells that otherwise lead to tumor recurrence and death 
of the patient.
Submitter
Rolf F. Barth.
Affiliation and email
The Ohio State University, Columbus, OH, USA.
rolf.barth@osumc.edu.
Page 5 of 5Chinese Journal of Cancer  Chin J Cancer  (2017) 36:33 
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Received: 17 March 2017   Accepted: 17 March 2017
References
 1. Qian CN, Zhang W, Xu RH. Defeating cancer: the 150 most important 
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The 150 most important questions in cancer research and clinical oncology series: questions 6–14

Cauchy problem of the generalized Zakharov type system in 
                  

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