36 research outputs found
Effects of cloud condensate vertical alignment on radiative transfer calculations in deep convective regions
No full textAbstractEffects of cloud condensate vertical alignment on radiative transfer process were investigated using cloud resolving model explicit simulations, which provide a surrogate for subgrid cloud geometry. Diagnostic results showed that the decorrelation length Lcw varies in the vertical dimension, with larger Lcw occurring in convective clouds and smaller Lcw in cirrus clouds. A new parameterization of Lcw is proposed that takes into account such varying features and gives rise to improvements in simulations of cloud radiative forcing (CRF) and radiative heating, i.e., the peak of bias is respectively reduced by 8Wm−2 for SWCF and 2Wm−2 for LWCF in comparison with Lcw=1km.The role of Lcw in modulating CRFs is twofold. On the one hand, larger Lcw tends to increase the standard deviation of optical depth στ, as dense and tenuous parts of the clouds would be increasingly aligned in the vertical dimension, thereby broadening the probability distribution. On the other hand, larger στ causes a decrease in the solar albedo and thermal emissivity, as implied in their convex functions on τ. As a result, increasing (decreasing) Lcwleads to decreased (increased) CRFs, as revealed by comparisons among Lcw=0, Lcw=1km andLcw=∞. It also affects the vertical structure of radiative flux and thus influences the radiative heating. A better representation of στ in the vertical dimension yields an improved simulation of radiative heating. Although the importance of vertical alignment of cloud condensate is found to be less than that of cloud cover in regards to their impacts on CRFs, it still has enough of an effect on modulating the cloud radiative transfer process
Sorting lung tumor volumes from 4D-MRI data using an automatic tumor-based signal reduces stitching artifacts
No full textPURPOSE: To investigate whether a novel signal derived from tumor motion allows more precise sorting of 4D-magnetic resonance (4D-MR) image data than do signals based on normal anatomy, reducing levels of stitching artifacts within sorted lung tumor volumes. METHODS: (4D-MRI) scans were collected for 10 lung cancer patients using a 2D T2-weighted single-shot turbo spin echo sequence, obtaining 25 repeat frames per image slice. For each slice, a tumor-motion signal was generated using the first principal component of movement in the tumor neighborhood (TumorPC1). Signals were also generated from displacements of the diaphragm (DIA) and upper and lower chest wall (UCW/LCW) and from slice body area changes (BA). Pearson r coefficients of correlations between observed tumor movement and respiratory signals were determined. TumorPC1, DIA, and UCW signals were used to compile image stacks showing each patient's tumor volume in a respiratory phase. Unsorted image stacks were also built for comparison. For each image stack, the presence of stitching artifacts was assessed by measuring the roughness of the compiled tumor surface according to a roughness metric (Rg). Statistical differences in weighted means of Rg between any two signals were determined using an exact permutation test. RESULTS: The TumorPC1 signal was most strongly correlated with superior-inferior tumor motion, and had significantly higher Pearson r values (median 0.86) than those determined for correlations of UCW, LCW, and BA with superior-inferior tumor motion (p < 0.05). Weighted means of ratios of Rg values in TumorPC1 image stacks to those in unsorted, UCW, and DIA stacks were 0.67, 0.69, and 0.71, all significantly favoring TumorPC1 (p = 0.02-0.05). For other pairs of signals, weighted mean ratios did not differ significantly from one. CONCLUSION: Tumor volumes were smoother in 3D image stacks compiled using the first principal component of tumor motion than in stacks compiled with signals based on normal anatomy
Sorting lung tumor volumes from 4D-MRI data using an automatic tumor-based signal reduces stitching artifacts.
No full textTo investigate whether a novel signal derived from tumor motion allows more precise sorting of 4D-magnetic resonance (4D-MR) image data than do signals based on normal anatomy, reducing levels of stitching artifacts within sorted lung tumor volumes. (4D-MRI) scans were collected for 10 lung cancer patients using a 2D T2-weighted single-shot turbo spin echo sequence, obtaining 25 repeat frames per image slice. For each slice, a tumor-motion signal was generated using the first principal component of movement in the tumor neighborhood (TumorPC1). Signals were also generated from displacements of the diaphragm (DIA) and upper and lower chest wall (UCW/LCW) and from slice body area changes (BA). Pearson r coefficients of correlations between observed tumor movement and respiratory signals were determined. TumorPC1, DIA, and UCW signals were used to compile image stacks showing each patient's tumor volume in a respiratory phase. Unsorted image stacks were also built for comparison. For each image stack, the presence of stitching artifacts was assessed by measuring the roughness of the compiled tumor surface according to a roughness metric (Rg). Statistical differences in weighted means of Rg between any two signals were determined using an exact permutation test. The TumorPC1 signal was most strongly correlated with superior-inferior tumor motion, and had significantly higher Pearson r values (median 0.86) than those determined for correlations of UCW, LCW, and BA with superior-inferior tumor motion (p < 0.05). Weighted means of ratios of Rg values in TumorPC1 image stacks to those in unsorted, UCW, and DIA stacks were 0.67, 0.69, and 0.71, all significantly favoring TumorPC1 (p = 0.02-0.05). For other pairs of signals, weighted mean ratios did not differ significantly from one. Tumor volumes were smoother in 3D image stacks compiled using the first principal component of tumor motion than in stacks compiled with signals based on normal anatomy
Initial state and transition-state solvation effects in the cobaltotungstate oxidation of iodide in binary aqueous solvent mixtures
No full textPT: J; CR: AMJAD Z, 1977, CAN J CHEM, V55, P3581 BAKER LCW, 1956, J AM CHEM SOC, V78, P4503 BECK MT, 1968, COORDIN CHEM REV, V3, P91 BLANDAMER MJ, UNPUB CAN J CHEM BLANDAMER MJ, 1978, J CHEM SOC CHEM COMM, P963 BLANDAMER MJ, 1979, PURE APPL CHEM, V51, P2087 BLANDAMER MJ, 1980, COORDIN CHEM REV, V31, P93 BLANDAMER MJ, 1980, J CHEM SOC DA, P1 BLANDAMER MJ, 1980, J CHEM SOC DA, P2442 BRODOVITCH JC, UNPUB BURGESS J, 1968, J CHEM SOC A, P2571 BURGESS J, 1970, J CHEM SOC A, P2111 BURGESS J, 1970, J CHEM SOC A, P2351 BURGESS J, 1972, INORGANIC REACTION M, V2, P127 BURGESS J, 1973, J CHEM SOC A, P825 BURGESS J, 1974, INORGANIC REACTION M, V3, P142 BURGESS J, 1977, INORGANIC REACTION M, V5, P158 BURGESS J, 1979, INORGANIC REACTION M, V6, P168 COX BG, 1974, ANN REP CHEM SOC A, V71, P249 COX BG, 1979, J CHEM SOC F1, V75, P1780 COX BG, 1979, J CHEM SOC FARAD T 1, V75, P86 DELIGNY CL, 1965, RECL TRAV CHIM PAY B, V84, P81 ELLIS KJ, 1973, J CHEM SOC DA, P1533 GRUNWALD E, 1948, J AM CHEM SOC, V70, P846 KANEMAQUIRE LAP, 1975, J CHEM SOC DA, P1890 KEPERT DL, 1978, J CHEM SOC DA, P137 MARCUS RA, 1968, J PHYS CHEM-US, V72, P891 PELIZZETTI E, 1976, INORG CHEM, V15, P2898 SUBHANI MS, 1978, REV ROUMAINE CHIM, V23, P719 UDOVENKO VV, 1977, RUSS J INORG CHEM, V22, P168 WELLS CF, 1973, J CHEM SOC FARAD T 1, V69, P984 WELLS PR, 1968, LINEAR FREE ENERGY R, CH4; NR: 32; TC: 14; J9: TRANSIT METAL CHEM; PG: 4; GA: NG073Source type: Electronic(1
Distributed and collaborative intrusion detection systems
No full textIntrusion detectiom systems help improve the security of networks by providing early warning and response. To improove the detetion of attacks, sharing data among distributed nodes or terminals and collaborating on. a decision is key. This paper presents a Distributed and Cot laborative In-irtrusion Detection (DaCID) system that relies on Dempster Shafer theory of evidence for fusing data from multiple nodes. In this approach the detection is done collaboratively and the decision is distributed among all nodes. DaCID is more robust than other systems since it is completely distributed and the decision is made autonomously at each node. Simulation results demonstrated. that DaCID's performance approaches that of a centraliied method. © 2008 IEEE.ALLEN M, INDEPENDENT SECURITY; Blanc M., 2003, GLOBAL INTRUSION DET; DERI L, 2003, P TER TNC; DRESSLER F, 2004, 1 IFIP INT WORKSH AU; KANNADIGA P, 2005, P 6 IEEE INT C SOFTW; Madan BB, 2004, PERFORM EVALUATION, V56, P167, DOI 10.1016-j.peva.2003.07.008; Mirkovic J, 2005, IEEE T DEPEND SECURE, V2, P216, DOI 10.1109-TDSC.2005.35; MIRKOVIC J, 2004, 020018 U CAL COMP SC; NAJMI, 2005, TECHIWAREHOUSE 1026; Papadopoulos Christos, 2003, P DARPA INF SURV C E; PORRAS PA, 1998, INT SOC NETW DISTR S; PORRAS PA, 1997, P NAT INF SYST SEC C; RICHARDSON R, 2007, 2007 CSI COMPUTER CR; Siaterlis C., 2005, Journal of Computer Security, V13; SINGH A, 2005, SECURITYFOCUS W 1214; WU YS, 2003, P 19 IEEE ANN COMP S; ZHAI JQ, 2003, P 2 INT C MACH LEARN21
Liver-Targeting of Interferon-Alpha with Tissue-Specific Domain Antibodies
No full textPMCID: PMC3581439This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
Studies on Pathogenesis of Atherosclerosis (Report I)
No full textThere are studies indicating a delayed increase In
the rate of hepatic biosynthesis of fatty acids in
whole-body X-irradiated albino rats, as indicated by
measurements of acetate-I-C 14 incorporation 1-3).
And, in particular, considerable augmentation of
cholesterol biosynthesis from acetate in the albino
rat liver and adrenals by exposure of the animals to
X-irradiation.,5) and also by injection of the detergent
Triton WR 13396) have been reported. On the
other hand, suppression of the biosynthetic rate was
obsevred in animals deprived of food for 24 to 48
hours7. 8) or when fed a cholesterol-enriched diet 9- 13)
or when administered 4-cholestenone14•15).
Thus, regulation of cholesterol homeostatis in ani·
mals by variation in the rate of cholesterol biosynthesis
appears to be primarily a function of the liver.
It is, therefore, quite natural to expect that radiant
energy absorbed in the liver tissue will no doubt
cause a significant disturbance with regard to homeostasis
of living cells. In addition to X-ray, the author
was interested in any alteration of cholesterol biosynthesis
caused by administration of ginseng extract,
carbon-tetrachloride and ethyl-alcohol to albino rats.
Though there are many steps not yet elucidated
regarding cholesterol biosynthesis from acetate, it is
postulated that three molecules of acetate combine
to form branched chain intermediates of six carbon,
which, in turn, yield by multiple condensationsqualen.
Squalen, in a later stage, is cyclized into lanosterol
which is, in turn, transformed into cholesterol.
The purpose of the present investigation was to
study the variation in the biosynthetic rate of cholesterol
in the liver after whole-body Xvirradiauon
and ginseng extract, carbon-tetrachloride and ethylalcohol
administration to albino rats compared with
that in normal rats by measuring the incorporation
rate of acetate-LCw into a cell free homogenate of
liver
Neuropsychiatric symptoms are associated with increased risks of progression to dementia: A 2-year prospective study of 321 Chinese older persons with mild cognitive impairment
No full textBackground: studies have suggested that neuropsychiatric (NP) symptoms influence the development of dementia among older adults. But, the results are inconsistent and there is limited information about NP symptoms in population-based samples. Objective: to explore the association between NP symptoms and risk of cognitive decline in Chinese older persons residing in the community. Design: prospective study. Setting: community sample. Subjects: a total of 321 community-dwelling Chinese older persons aged 60 or over with mild cognitive impairment participated in the study. Methods: at baseline, each subject was assessed with Clinical Dementia Rating (CDR), Mini-Mental State Examination, list learning and delayed recall, and Category Verbal Fluency Test. Severity of NP symptoms was evaluated with Neuropsychiatric Inventory (NPI). Global cognitive status at the end of 2-year study period was determined by CDR. Results: at baseline, 40.5% of participants exhibited one or more NP symptoms (NPI total score ≥1). Night-time behaviours (22.1%), depression (16.8%), apathy (14.0%) and anxiety (12.8%) were the most common NP symptoms. At the end of 2-year follow-up, 27.5% of participants with depression at baseline developed dementia, compared with 14.8% of those without depression (χ 2=4.90, P= 0.03). Aberrant motor behaviour was also significantly associated with deterioration in cognition (χ 2= 5.84, P= 0.02), although it was an infrequent occurrence. On logistic regression analysis, only depression at baseline was shown to be a risk factor for progression to dementia (OR= 2.40, 95% CI 1.05-5.46, P= 0.04). Conclusion: depression in non-demented older persons may represent an independent dimension reflecting early neuronal degeneration. Further studies should be conducted to assess whether effective management of NP symptoms exerts beneficial effects on cognitive function. © The Author 2010. Published by Oxford University Press on behalf of the British Geriatrics Society. All rights reserved.link_to_subscribed_fulltex
Spatial and temporal analyses of Hong Kong coral communities as baseline information for resilience assessment
No full textM.Phil.Coral reefs are highly productive ecosystems that can support high biodiversity within a very small space and are often regarded as ‘the tropical rainforest in the ocean’. They are facing various threats such as global warming, eutrophication and overfishing. In view of all the threats, resilience assessment on coral communities has attracted much attention in tropical reefs. Resilience is defined as ‘the ability of a system to absorb change and disturbance and still maintain or return to the same ecological function. Researchers have proposed the indicators to be assessed and the corresponding methods to be used to assess the resilience of tropical reefs. Similar approach should be modified to fit into the unique situations in Hong Kong and applied in Hong Kong and other subtropical or marginal non-reef communities. For resilience assessment in Hong Kong, much information is needed. Coral cover and community structure, and the factors affecting them are among the top prioritized indicators that can be used.Therefore, in this study, benthic surveys by photoquadrat-transect method were conducted in 18 selected sites in Hong Kong water, eight of these sites are within marine parks (or marine protected areas (MPAs)), four in no-anchoring areas (NAAs) and six in non-protected areas (NPAs). A general trend of increasing hard coral (HC) cover and diversity from western to eastern and northeastern waters was revealed as expected. In general, coral communities in eastern and northeastern waters are similarly dominated by stress-tolerant corals. Water quality data (WQD) were also obtained from authorities of Hong Kong SAR Government and used for multivariate correlation analyses with the biotic data to see if the patterns (if any) in biotic data can be explained by the environmental parameters in a local and finer scale. Results showed that the coral communities were generally too similar in their composition and structure so only regional scale differences can be detected. The lower HC covers in the southern sites were correlated with higher nutrients and lower salinity. Coral communities in eastern and northeastern sites were dominated by stress-tolerant species. Exceptions were found in Ung Kong (UK) and Au Yue Tsui (AYT), where the two coral communities reacted very differently to eutrophied water. However, because the water quality data (WQD) in coastal areas are very different from those obtained from marine monitoring stations of EPD in more openwater areas, with the lack of coastal WQD in non-MPA sites, the correlation results with non-MPA sites may be misleading. This also limited the power of the correlation tests since MPA and non-MPA sites needed to be analyzed separately.Meanwhile, past data from 8 to 11 years ago are available from previous reports in 10 of the 18 sites, all of them are within northeastern water. These data were compared with data obtained in the present study by multivariate analyses. Results indicated that marine parks were reasonably effective in coral protections. Coral covers in the sites within Hoi Ha Wan Marine Park (HHWMP) were generally stable over time but with some fluctuations and exceptions. In Tung Ping Chau Marine Park (TPCMP), the coral covers increased over time albeit the increase was not statistically significant, and the benthic compositions remained fairly the same. The study sites in TPCMP were dominated by Porites and Platygyra spp., both massive corals which are considered to be stress-tolerant. In general, the multivariate analyses could not distinguish the differences and changes in biotic data and their correlation with the available environmental data because the biotic benthic and coral compositions were too similar among sites. However, the coincidental decrease of HC cover in AYT, Lai Chi Wo (LCW) and Cheung Shek Tsui (CST) was suspected to be influenced by port development in Shenzhen, Guangdong over the past decade, as the three sites were located closest to Shenzhen.The dominance of stress-tolerant corals in Hong Kong coral communities might imply that the marine environments are already too stressful for other types of corals to grow and compete. The highly similar coral communities in the eastern and northeastern water cannot be explained by the available WQD. More data from coastal areas should be obtained in the future for the study and monitoring of coral communities and other coastal habitats. The present study contributed to the development of resilience study by providing the major information about Hong Kong coral communities: their coral cover, coral species composition, temporal changes (up to 11 years in some locations), the influence of marine environment and the limitations of current biological and environmental monitoring. This could provide some baseline information and implications for the development of a more complete assessment on coral resilience in Hong Kong, as well as management strategies for the conservation of Hong Kong corals and marine environment.珊瑚礁是高生產力的生態系統，在很小的空間內支持很高的生物多樣性，常被稱之為「海洋中的熱帶雨林」。 珊瑚礁正面臨各式各樣的威脅： 例如全球暖化、海洋酸化及過度捕撈等。 有鑑於珊瑚礁正面臨的各種威脅，珊瑚群落的恢復力評估在熱帶珊瑚礁引起了極大的關注。 恢復力被定義為「生態系統在遇到變化和干擾之後，仍能保持於或回復到原本的生態功能之能力」。研究人員提出了需要評估的參考指標以及用於評估熱帶珊瑚礁恢復力的相應方法。 類似的方法也應該應用到香港和其他亞熱帶或邊緣地區的非礁石群落。但這些方法在應用前需要先進行修改，才能套用到香港的特殊情況。要評估香港珊瑚群落的恢復力，需要很多資料，而珊瑚覆蓋和群落結構，以及影響它們的因素，便是研究珊瑚群落恢復力的首要指標之一。因此，本研究在十八個香港水域內的選址，並以樣線樣方的方式，進行了底棲調查。 十八個研究地點之中，有八個位於海岸公園（或海洋保護區（MPA））內，四個在不宜碇泊區（NAA），六個在非保護區（NPA）。 結果顯示，從西部到東部及東北部水域，石珊瑚的覆蓋率和多樣性如預期一樣具有增加的趨勢。 一般來說，東部和東北部水域的珊瑚群落都被耐壓珊瑚所支配。 此外，香港特別行政區的政府部門亦提供水質數據（WQD）以便與生物數據進行多變量分析，對底棲生物、珊瑚物種和生命策略史的構成進行更仔細的多變量相關性測試，以解析生物數據中出現的模式（如有的話）。 結果顯示，珊瑚群落的結構一般都很相似，分析只能區分地域差異。 南部地區較低的石珊瑚覆蓋率與較高的營養和較低的鹽度有關。 東部和東北部地點的珊瑚群落都以耐壓珊瑚為主要品種。其中甕缸（UK）以及拗魚嘴（AYT）是個例外，而兩個珊瑚群落對富營養化的水都有不同的反應。 然而，由於沿岸地區的水質數據較環保署海洋監測站獲得的開放地區的水質數據截然不同，加上在缺少非MPA 地區的水質數據下，與非MPA 地點的相關性測試結果可能會有誤導。 而MPA 和非MPA 地點的數據亦因此需要分開分析，進而限制了相關性測試的功能 。同時，在以前的報告中，能夠獲取十八個地點裡其中十個研究地點的歷史數據，十個研究地點都在東北部水域內，這些數據有著八至十一年歷史。將這些歷史數據與本研究中獲得的數據作比較，進行多變量分析。 結果顯示，海岸公園在保護珊瑚方面相當有效。 海下灣海岸公園（HHWMP）內的石珊瑚覆蓋率除了一些波動和例外之外，整體可算穩定。 在東坪洲海岸公園（TPCMP），珊瑚覆蓋率隨著時間的推移而增加，可是增幅並不顯著，同時底棲成分亦保持不變。 在TPCMP 的兩個研究地點都以濱珊瑚屬（Porites）和扁腦珊瑚屬（Platygyra）為主要的珊瑚覆蓋，這兩個大型團塊形珊瑚都是耐壓品種。 一般而言，多變量分析無法區分生物數據的差異和變化及其與現有環境數據的相關性。這是因為生物基底和珊瑚組成成分在研究地點之間太相似。不過，過去十年來，拗魚嘴（AYT）、荔枝窩（LCW）及長石咀（CST）懷疑受到深圳港口的發展的影響，珊瑚覆蓋率都同時下降。香港珊瑚群落都以耐壓珊瑚為主，可能意味著海洋環境已經不利於其他類型的珊瑚生長或與之競爭。 東部和東北部水域高度相似的珊瑚群落都不能用現有的水質數據來解釋。 今後應收取更多來自沿海地區的資料，以用作研究和監測珊瑚群落及其他沿海生境。 本研究通過提供有關香港珊瑚群落的主要資料，包括珊瑚覆蓋率、珊瑚物種之構成及它們時間上的變化（某些地區多達十一年）、海洋環境的影響、以及目前對生物和環境監測的局限性。 這為更完整地評估香港珊瑚恢復力、以及保育香港珊瑚及海洋環境的管理策略，提供一些基礎數據及啟示。Leung, Yu Hin.Thesis M.Phil. Chinese University of Hong Kong 2017.Includes bibliographical references (leaves 228-239).Abstracts also in Chinese.Title from PDF title page (viewed on …)
Low population Japanese encephalitis virus (JEV) seroprevalence in Udayapur district, Nepal, three years after a JE vaccination programme: a case for further catch up campaigns?
No full textThe live attenuated Japanese encephalitis (JE) vaccine SA14-14-2 has been used in Nepal for catch-up campaigns and is now included in the routine immunisation schedule. Previous studies have shown good vaccine efficacy after one dose in districts with a high incidence of JE. The first well-documented dengue outbreak occurred in Nepal in 2006 with ongoing cases now thought to be secondary to migration from India. Previous infection with dengue virus (DENV) partially protects against JE and might also influence serum neutralising antibody titres against JEV. This study aimed to determine whether serum anti-JEV neutralisation titres are: 1. maintained over time since vaccination, 2. vary with historic local JE incidence, and 3. are associated with DENV neutralising antibody levels. We conducted a cross-sectional study in three districts of Nepal: Banke, Rupandehi and Udayapur. Udayapur district had been vaccinated against JE most recently (2009), but had been the focus of only one campaign, compared with two in Banke and three in Rupandehi. Participants answered a short questionnaire and serum was assayed for anti-JEV and anti-DENV IgM and IgG (by ELISA) and 50% plaque reduction neutralisation titres (PRNT50) against JEV and DENV serotypes 1–4. A titre of ≥1:10 was considered seropositive to the respective virus. JEV neutralising antibody seroprevalence (PRNT50 ≥ 1:10) was 81% in Banke and Rupandehi, but only 41% in Udayapur, despite this district being vaccinated more recently. Sensitivity of ELISA for both anti-JEV and anti-DENV antibodies was low compared with PRNT50. DENV neutralising antibody correlated with the JEV PRNT50 ≥1:10, though the effect was modest. IgM (indicating recent infection) against both viruses was detected in a small number of participants. We also show that DENV IgM is present in Nepali subjects who have not travelled to India, suggesting that DENV may have become established in Nepal. We therefore propose that further JE vaccine campaigns should be considered in Udayapur district, and similar areas that have had fewer vaccination campaigns
