15,248 research outputs found
Link stability estimation based on link connectivity changes in mobile ad-hoc networks
No full textDear Wang,
Re: Link Stability Estimation Based on Link Connectivity Changes in Mobile Ad-hoc Networks
I have not been able to assess if this is an author version peer-reviewed or is it an author version non peer reviewed. Could you please clarify this so I can proceed to add your paper to Spiral. Spiral digital repository only accept peer-reviewed papers.
30/11/12 author has confirmed peer reviewe
Cerebral atrophy in mild cognitive impairment and Alzheimer disease: rates and acceleration.
No full textOBJECTIVE: To quantify the regional and global cerebral atrophy rates and assess acceleration rates in healthy controls, subjects with mild cognitive impairment (MCI), and subjects with mild Alzheimer disease (AD). METHODS: Using 0-, 6-, 12-, 18-, 24-, and 36-month MRI scans of controls and subjects with MCI and AD from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database, we calculated volume change of whole brain, hippocampus, and ventricles between all pairs of scans using the boundary shift integral. RESULTS: We found no evidence of acceleration in whole-brain atrophy rates in any group. There was evidence that hippocampal atrophy rates in MCI subjects accelerate by 0.22%/year2 on average (p = 0.037). There was evidence of acceleration in rates of ventricular enlargement in subjects with MCI (p = 0.001) and AD (p < 0.001), with rates estimated to increase by 0.27 mL/year2 (95% confidence interval 0.12, 0.43) and 0.88 mL/year2 (95% confidence interval 0.47, 1.29), respectively. A post hoc analysis suggested that the acceleration of hippocampal loss in MCI subjects was mainly driven by the MCI subjects that were observed to progress to clinical AD within 3 years of baseline, with this group showing hippocampal atrophy rate acceleration of 0.50%/year2 (p = 0.003). CONCLUSIONS: The small acceleration rates suggest a long period of transition to the pathologic losses seen in clinical AD. The acceleration in hippocampal atrophy rates in MCI subjects in the ADNI seems to be driven by those MCI subjects who concurrently progressed to a clinical diagnosis of AD
A Fair and Secure Cluster Formation Process for Ad Hoc Networks
No full textAn efficient approach for organizing large ad hoc networks is to divide the nodes
into multiple clusters and designate, for each cluster, a clusterhead which is responsible for
holding intercluster control information. The role of a clusterhead entails rights and duties.
On the one hand, it has a dominant position in front of the others because it manages the
connectivity and has access to other node¿s sensitive information. But on the other hand, the
clusterhead role also has some associated costs. Hence, in order to prevent malicious nodes
from taking control of the group in a fraudulent way and avoid selfish attacks from suitable
nodes, the clusterhead needs to be elected in a secure way. In this paper we present a novel
solution that guarantees the clusterhead is elected in a cheat-proof manner
Energy efficiency in ad-hoc wireless networks
No full textIn ad-hoc wireless networks, nodes are typically battery-powered, therefore energy limitations are among the critical constraints in ad-hoc wireless networks' development. The approaches investigated in this thesis to achieve energy efficient performance in wireless networks
can be grouped into three main categories.
1. Each wireless network node has four energy consumption states: transmitting, receiving, listening and sleeping states. The power consumed in the listening state is less than the power consumed in the transmitting and receiving states, but significantly greater than that in the sleeping state. Energy efficiency is achieved if as many nodes as possible are put into the sleeping states.
2) Since energy is consumed for transmission nonlinearly in terms of the transmission range, transmission range adjustment is another energy saving approach. In this work, the optimal transmission range is derived and applied to achieve energy efficient performance in a number of scenerios.
3) Since energy can be saved properly arranging the communication algorithms, network topology management or network routing is the third approach which can be utilised in combination with the above two approaches. In this work, Geographical Adaptive Fidelity (GAF) algorithms, clustering algorithms and Geographic Routing (GR) algorithms are all utilised to reduce the energy consumption of wireless networks, such as Sensor Networks and Vehicular Networks.
These three approaches are used in this work to reduce the energy consumption of wireless networks. With the GAF algorithm. We derived the optimal transmission range and optimal grid size in both linear and rectangular networks and as a result we show how the network energy consumptions can be reduced and how the network lifetime can be prolonged. With Geographic Routing algorithms the author
proposed the Optimal Range Forward (ORF) algorithm and Optimal Forward with Energy Balance (OFEB) algorithm to reduce the energy consumption and to prolong the network lifetime. The results show that compared to the traditional GR algorithms (Most Forward within Radius, Nearest Forward Progress), the network lifetime is prolonged. Other approaches have also been considered to improve the networks's energy efficient operation utilising Genetic Algorithms to find the optimal size of the grid or cluster. Furthermore realistic physical layer models, Rayleigh fading and LogNormal fading, are considered in evaluating energy efficiency in a realistic network environment
The impact of mobility models on the performance of mobile Ad Hoc network routing protocol
No full textA mobility model represents nodes distribution and movement over the network. Several research works have shown that a selection of mobility model can affect the outcome of routing performance simulation in Mobile Ad Hoc Networks. Thus, a routing protocol may only be effective in a particular mobility model or scenario but performs inferiorly in another. As a result, analyses of routing protocol performance are often based on inadequate information leading to inaccurate argument and conclusion. In this paper, three different mobility models have been selected, where each of them is highly distinctive in terms of nodes movement behavior. In addition, a new measurement technique called probability of route connectivity is introduced. The technique is used to quantify the success rate of route established by a routing protocol. Extensive simulation runs are done and results are compared between each mobility model
Internet connection method for mobile ad hoc wireless networks
No full textIn recent years, wireless networks with Internet services have become more and
more popular. Technologies which integrate Internet and wireless networks have
extended traditional Internet applications into a more flexible and dynamic
environment. This research work investigates the technology that supports the
connection between a Mobile Ad Hoc Wireless Network (MANET) and the
Internet, which enables the current wireless Internet technologies to provide a
ubiquitous wireless life style.
With detailed analysis of the existing wireless Internet technologies and
MANETs regarding their features and applications, the demand and lack of
research work for an application to provide Internet connection to MANET is
indicated. The primary difficulty for MANET and Internet connection is that the
dynamic features of MANET do not suit the traditional connection methods used
in infrastructure wireless networks. This thesis introduces new concept of the
'Gateway Awareness' (GAW) to the wireless devices in the MANET. GAW is a
new routing protocol designed by the author of this thesis, at the University of
Warwick. Based on GAW, an inclusive definition for the connection method,
which supports the Internet connection and keeps the independency of routing in
MANET, is addressed. Unlike other research work, this method supports the
MANET and Internet communication in both directions. Furthermore, it explores
possible ways of using the Internet as an extension for wireless communications.
The GAW routing method is developed from destination sequenced distance
vector (DSDV) routing protocol. However, it defines a layer of wireless nodes
(known as GAWNs) with exclusive functions for the Internet connection task.
The layer of GAWNs brings a new set of route update and route selection
method. Simulations show that the GAW routing method provides quality
Internet connection performance in different scenarios compared with other
methods. In particular, the connection is completed with minimum effect on the
independent MANET while the routing efficiency and accuracy is guaranteed
Funeral March to the Memory of Cornelius Vanderbilt.
No full textda capo with trio and codapiano[Cornelius Vanderbilt].9273Johns Hopkins University, Levy Sheet Music Collection, Box
057, Item 126aComposed by Ad. Meyer.Ferd. Mayer, Gen'l Lith's, 96 & 98 Fulton St. N.Y
Funeral March to the Memory of Cornelius Vanderbilt.
No full textda capo with trio and codapiano[Cornelius Vanderbilt].9273Johns Hopkins University, Levy Sheet Music Collection, Box
057, Item 126aComposed by Ad. Meyer.Ferd. Mayer, Gen'l Lith's, 96 & 98 Fulton St. N.Y
Salter vs Pemberton: сравнительный рентгенологический анализ изменения вертлужной впадины и таза после хирургической коррекции у детей с врожденным вывихом бедра
No full textBackground. Hip dysplasia, characterized by pronounced anatomical changes, continues to be one of the leading positions in the structure of all congenital malformations of the musculoskeletal system. Late diagnosis or ineffective conservative treatment leads to the need for surgical correction of congenital deformities of the proximal femur and acetabulum. The choice of the method of operational reconstruction of the latter remains a subject of discussion over the past decades.
Aim of the study a comparative X-ray analysis of surgical treatment outcomes of children with hip dysplasia type IHDI III-IV after Salter and Pemberton pelvic osteotomies.
Methods. The study included 80 patients (80 hip joints) aged 2 to 4 years (3.1 0.45) with hip dysplasia of the III-IV degree according to the IHDI. Patients were divided into two groups: group I consisted of 40 patients who underwent modified Salter osteotomy, group II 40 patients who underwent Pemberton pericapsular acetabuloplasty. Radiometry of the following parameters was performed: acetabular index (AI), Wiberg angle, neck-shaft angle, anteversion angle of the proximal femur, degree of bone coverage, the depth of the acetabulum (AD) and pelvic height (PH)
Results. The values of AI and Wiberg angle in patients in I group indicate that a greater correction was achieved (p0.05) in contrast to patients who underwent Pemberton pericapsular acetabuloplasty. At the same time, the values of AD and PH in I group patients had pronounced differences (p0.05) from those in II group patients, whose values were close to similar indicators in the contralateral hip joint.
Conslusions. In the treatment of children with hip dysplasia IHDI III-IV degree performing a modified Salter osteotomy leads to a significant decrease in the values of AI and an increase in the values of the Wiberg angle, which corresponds to hypercorrection of the position of the acetabulum, does not affect the AD and contributes to the elongation of the hemipelvis by an average of 13.8 mm. Pemberton acetabuloplasty allows to achieve values of AI and Wiberg angle close to the age-related indicators of the norm, leads to an increase AD, approaching the contralateral joint in its value and does not significantly affect the PH.Актуальность. Дисплазия тазобедренных суставов, характеризующаяся выраженными анатомическими изменениями, продолжает оставаться на одной из лидирующих позиций в структуре всех врожденных пороков развития костно-мышечной системы. Поздняя диагностика или неэффективное консервативное лечение приводят к необходимости хирургической коррекции врожденных деформаций проксимального отдела бедренной кости и вертлужной впадины. Выбор метода оперативной реконструкции последней остается предметом дискуссии на протяжении последних десятилетий.
Цель исследования провести сравнительный рентгенологический анализ изменения строения вертлужной впадины и таза у детей с врожденным вывихом бедра (IIIIV степени по IHDI) после остеотомий таза по Salter и по Pemberton.
Материал и методы. В исследование вошли 80 пациентов (80 тазобедренных суставов) в возрасте от 2 до 4 лет (3,10,5) с дисплазией тазобедренных суставов IIIIV степени по классификации IHDI, получавших лечение в период с 2020 по 2021 г. Все дети были разделены на две группы: I группу составили 40 пациентов (40 тазобедренных суставов), которым выполняли модифицированную подвздошную остеотомию таза по Salter, II группу 40 пациентов (40 тазобедренных суставов), которым выполняли перикапсулярную ацетабулопластику по Pemberton. Проводили рентгенометрию следующих показателей: ацетабулярный индекс (АИ), угол Wiberg, шеечно-диафизарный угол, угол антеверсии проксимального отдела бедренной кости, степень костного покрытия, глубина вертлужной впадины (AD) и высота таза (PH).
Результаты. Ближайшие результаты оценивались через 6 мес. Значения АИ и угла Wiberg у пациентов, которым была выполнена модифицированная остеотомия таза по Salter, говорят о достижении большей коррекции (p0,05) в отличие от пациентов, которым была выполнена перикапсулярная ацетабулопластика по Pemberton. Вместе с тем значения AD и PH у пациентов I группы имели выраженные отличия (p0,05) от таковых у пациентов II группы, значения которых были приближены к аналогичным показателям в контралатеральном интактном тазобедренном суставе.
Заключение. При лечении детей с дисплазией тазобедренных суставов IIIIV степени по классификации IHDI выполнение модифицированной остеотомии таза по Salter приводит к значительному уменьшению значений АИ и увеличению значений угла Wiberg, что соответствует гиперкоррекции положения вертлужной впадины, не влияет на глубину вертлужной впадины и способствует удлинению гемипельвиса в среднем на 13,8 мм. Перикапсулярная остеотомия таза по Pemberton позволят достичь значений АИ и угла Wiberg, близких к возрастным показателям нормы, приводит к увеличению глубины вертлужной впадины, приближающейся по своему значению к контралатеральному суставу, и не оказывает отрицательного влияния на высоту таза
Consensu Et Author. Magnifici Ictorum Ordinis In Illustri Ad Salam Academia, Sub Praesidio ... Dn. Joh. Volk. Bechmanns ... Dissertationem Iuridicam De Iure Braxandi in Ictorum Auditorio ad diem Octobr. h.c. Publicae Eruditorum Censurae Subiiciet Paul. Christianus Arnoldus, Olsnen. Siles. Author & Respondens
No full textCONSENSU ET AUTHOR. MAGNIFICI ICTORUM ORDINIS IN ILLUSTRI AD SALAM ACADEMIA, SUB PRAESIDIO ... DN. JOH. VOLK. BECHMANNS ... DISSERTATIONEM IURIDICAM DE IURE BRAXANDI IN ICTORUM AUDITORIO AD DIEM OCTOBR. H.C. PUBLICAE ERUDITORUM CENSURAE SUBIICIET PAUL. CHRISTIANUS ARNOLDUS, OLSNEN. SILES. AUTHOR & RESPONDENS
Consensu Et Author. Magnifici Ictorum Ordinis In Illustri Ad Salam Academia, Sub Praesidio ... Dn. Joh. Volk. Bechmanns ... Dissertationem Iuridicam De Iure Braxandi in Ictorum Auditorio ad diem Octobr. h.c. Publicae Eruditorum Censurae Subiiciet Paul. Christianus Arnoldus, Olsnen. Siles. Author & Respondens ([1])
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