bluuebunny/crossref_metadata_2025_split huggingface dataset:
A secure group communication architecture for autonomous unmanned aerial vehicles
Authors: Phillips Adrian N. , Mullins Barry E. , Raines Richard A. , Baldwin Rusty O. 
Published: August 2008

AbstractThis paper investigates the application of a secure group communication architecture to a swarm of autonomous unmanned aerial vehicles (UAVs). A multicast secure group communication architecture for the low earth orbit (LEO) satellite environment is evaluated to determine if it can be effectively adapted to a swarm of UAVs and provide secure, scalable, and efficient communications. The performance of the proposed security architecture is evaluated with two other commonly used architectures using a discrete event computer simulation developed using MATLAB. Performance is evaluated in terms of the scalability and efficiency of the group key distribution and management scheme when the swarm size, swarm mobility, multicast group join and departure rates are varied. The metrics include the total keys distributed over the simulation period, the average number of times an individual UAV must rekey, the average bandwidth used to rekey the swarm, and the average percentage of battery consumed by a UAV to rekey over the simulation period. The proposed security architecture can successfully be applied to a swarm of autonomous UAVs using current technology. The proposed architecture is more efficient and scalable than the other tested and commonly used architectures. Over all the tested configurations, the proposed architecture distributes 55.2–94.8% fewer keys, rekeys 59.0–94.9% less often per UAV, uses 55.2–87.9% less bandwidth to rekey, and reduces the battery consumption by 16.9–85.4%. Published in 2008 by John Wiley & Sons, Ltd.
Correction
Authors: Farrington C. P. 
Published: August 2008

AbstractAndrew Hill has kindly pointed out that some of the entries in Table I and Table II of ‘Sample sizes for self‐controlled case series studies’, by Musonda et al. (Statistics in Medicine 2006; 25: 2618–2631) are incorrect. Corrected versions of the tables are given below. The errors do not affect the substantive conclusions of the paper.

Empirical power for 80 per cent nominal value.

Sample size expression

r
ρ
(4)
(5)
(6)
(7)

0.01
0.5
81
75
81
83

1.5
78
84
80
78

2
78
87
82
77

3
78
88
79
80

5
70
95
77
84

10
79
98
80
68

0.05
0.5
84
80
78
82

1.5
77
84
81
79

2
76
85
84
79

3
70
88
84
77

5
77
95
82
76

10
63
97
89
78

0.1
0.5
90
73
80
84

1.5
78
82
80
79

2
78
86
81
80

3
67
84
81
75

5
68
89
79
84

10
82
97
79
87

0.5
0.5
92
77
76
81

1.5
73
80
80
80

2
77
76
76
81

3
77
82
84
84

5
76
78
76
77

10
97
81
81
81

Empirical power for 90 per cent nominal value.

Sample size expression

r
ρ
(4)
(5)
(6)
(7)

0.01
0.5
91
87
89
91

1.5
88
92
91
90

2
89
91
93
89

3
86
95
89
90

5
87
96
94
91

10
85
99
92
89

0.05
0.5
92
90
91
89

1.5
89
91
90
90

2
90
92
90
90

3
89
94
91
89

5
86
97
91
87

10
95
99
89
93

0.1
0.5
92
90
90
89

1.5
89
91
90
90

2
89
92
89
90

3
85
91
91
89

5
93
95
87
93

10
97
97
91
87

0.5
0.5
95
91
91
91

1.5
90
91
90
90

2
87
90
92
91

3
93
90
91
92

5
96
95
89
89

10
100
97
92
92
Analysing spatial and temporal variation in colony size: an approach using autoregressive mixed models and information theory
Authors: Olea Pedro P. 
Published: August 2008

AbstractThe spatial and temporal variation in population sizes of animal colonies are rarely studied simultaneously. I examined factors determining colony size (number of nests) for 23 colonies from the only breeding population of rook Corvus frugilegus in Spain over 7 years. Population sizes within colonies were highly predictable over time, with autocorrelations up to a distance (lag) of 6 years. Autoregressive mixed models were used to explain colony size as a function of environmental factors, while controlling for temporal autocorrelation. These factors included refuse tips, widely used as food resource, and a derived variable that incorporated the two factors most often related to avian colony size (inter‐colony competition and foraging habitat around colonies). Autoregressive models provided a better fit to the data than models which did not consider temporal autocorrelation. The information‐theoretic (AICc‐based) approach revealed uncertainty in the selection of the best model explaining colony‐size, but relatively strong support for certain variables. The highest weights of evidence were for year (ωi = 0.90) and the number of competitors per unit of foraging habitat (i.e., derived variable; ωi = 0.63), showing that the size of rook colonies in Spain was negatively affected by inter‐colony competition relative to the foraging habitat surrounding the colonies. This variable measured within a 6‐km radius from the colonies had ~30 times higher weight of evidence (more plausible) than the same variable measured within 3 km, indicating that food limitation may occur outside the breeding period. Sizes of colonies tended to decrease when distance between the colony and the nearest refuse tip increased. There was some evidence supporting the idea that the effect of the number of competitors per unit of foraging habitat on colony size varied from year to year, but statistical power was weak. These findings suggest that variation in number of rook nests within colonies reflects spatial and temporal heterogeneity of net food via both inter‐colony competition and foraging habitat around the colony.
Lower-limb growth: How predictable are predictions?
Authors: Kelly Paula M. , Diméglio Alain 
Published: August 2008

Purpose The purpose of this review is to clarify the different methods of predictions for growth of the lower limb and to propose a simplified method to calculate the final limb deficit and the correct timing of epiphysiodesis. Background Lower-limb growth is characterized by four different periods: antenatal growth (exponential); birth to 5 years (rapid growth); 5 years to puberty (stable growth); and puberty, which is the final growth spurt characterized by a rapid acceleration phase lasting 1 year followed by a more gradual deceleration phase lasting 1.5 years. The younger the child, the less precise is the prediction. Repeating measurements can increase the accuracy of predictions and those calculated at the beginning of puberty are the most accurate. The challenge is to reduce the margin of uncertainty. Confrontation of the different parameters—bone age, Tanner signs, annual growth velocity of the standing height, sub-ischial length and sitting height—is the most accurate method. Charts and diagrams are only models and templates. There are many mathematical equations in the literature; we must be able to step back from these rigid calculations because they are a false guarantee. The dynamic of growth needs a flexible approach. There are, however, some rules of thumb that may be helpful for different clinical scenarios. Calculation of limb length discrepancy For congenital malformations, at birth the limb length discrepancy must be multiplied by 5 to give the final limb length discrepancy. Multiple by 3 at 1 year of age; by 2 at 3 years in girls and 4 years in boys; by 1.5 at 7 years in girls and boys, by 1.2 at 9 years in girls and 11 years in boys and by 1.1 at the onset of puberty (11 years bone age for girls and 13 years bone age for boys). Timing of epiphysiodesis For the timing of epiphysiodesis, several simple principles must be observed to reduce the margin of error; strict and repeated measurements, rigorous analysis of the data obtained, perfect evaluation of bone age with elbow plus hand radiographs and confirmation with Tanner signs. The decision should always be taken at the beginning of puberty. A simple rule is that, at the beginning of puberty, there is an average of 5 cm growth remaining at the knee. There are four common different scenarios: (1) A 5-cm discrepancy—epiphysiodesis of both femur and tibia at the beginning of puberty (11 years bone age girls and 13 years in boys). (2) A 4-cm discrepancy—epiphysiodesis of femur and tibia 6 months after the onset of puberty (11 years 6 months bone age girls, 13 years 6 months bone age boys, tri-radiate cartilage open). (3) A 3-cm discrepancy—epiphysiodesis of femur only at the start of puberty, (skeletal age of 11 years in girls and 13 years in boys). (4) A 2-cm discrepancy—epiphysiodesis of femur only, 1 year after the start of puberty (12 years bone age girls and 14 years in boys).
Sucrose in the diet of 3-year-old Finnish children: sources, determinants and impact on food and nutrient intake
Authors: Erkkola Maijaliisa , Kronberg-Kippilä Carina , Kyttälä Pipsa , Lehtisalo Jenni , Reinivuo Heli , Tapanainen Heli , Veijola Riitta , Knip Mikael , Ovaskainen Marja-Leena , Virtanen Suvi M. 
Published: August 2008

The aim was to identify the important sources of added sucrose and determinants of high intake, and to evaluate what impact a high proportion of energy from added sucrose has on the intake of foods and nutrients. The subjects consisted of children invited to the nutrition study within the Type 1 Diabetes Prediction and Prevention birth cohort and born in 2001 (n846). Of these, 471 returned 3 d food records at 3 years of age. The average daily intake of added sucrose was 35 (sd17) g (11·3 % of energy intake) and that of total sucrose was 41 (sd18) g (13·3 % of energy intake). Sucrose added by manufacturers accounted for 82 %, naturally occurring sucrose for 15 % and sucrose added by consumers for 3 % of the total sucrose. Juice drinks, yoghurt/cultured milks, and chocolate and confectionery were the main contributors to added sucrose intake. Consumption of rye bread, porridge, fresh vegetables, cooked potatoes, skimmed milk, hard cheeses, margarine and fat spread as well as intake of most nutrients decreased across the quartiles of added sucrose (P < 0·05). Being cared for at home, having a father with a vocational school degree, having at least two siblings and a milk-restricted diet increased the risk for a high-sucrose diet. The study implied that a high proportion of added sucrose in the diet had mainly an unfavourable impact on the intake of recommended foods and key nutrients in Finnish children. The rationale for the recommendation to reduce the intake of refined sugars to ensure adequate intakes of nutrients seems reasonable.
High fat diet induces dysregulation of hepatic oxygen gradients and mitochondrial functionin vivo
Authors: Mantena Sudheer K. , Vaughn Denty Paul , Andringa Kelly K. , Eccleston Heather B. , King Adrienne L. , Abrams Gary A. , Doeller Jeannette E. , Kraus David W. , Darley-Usmar Victor M. , Bailey Shannon M. 
Published: August 2008

NAFLD (non-alcoholic fatty liver disease), associated with obesity and the cardiometabolic syndrome, is an important medical problem affecting up to 20% of western populations. Evidence indicates that mitochondrial dysfunction plays a critical role in NAFLD initiation and progression to the more serious condition of NASH (non-alcoholic steatohepatitis). Herein we hypothesize that mitochondrial defects induced by exposure to a HFD (high fat diet) contribute to a hypoxic state in liver and this is associated with increased protein modification by RNS (reactive nitrogen species). To test this concept, C57BL/6 mice were pair-fed a control diet and HFD containing 35% and 71% total calories (1 cal≈4.184 J) from fat respectively, for 8 or 16 weeks and liver hypoxia, mitochondrial bioenergetics, NO (nitric oxide)-dependent control of respiration, and 3-NT (3-nitrotyrosine), a marker of protein modification by RNS, were examined. Feeding a HFD for 16 weeks induced NASH-like pathology accompanied by elevated triacylglycerols, increased CYP2E1 (cytochrome P450 2E1) and iNOS (inducible nitric oxide synthase) protein, and significantly enhanced hypoxia in the pericentral region of the liver. Mitochondria from the HFD group showed increased sensitivity to NO-dependent inhibition of respiration compared with controls. In addition, accumulation of 3-NT paralleled the hypoxia gradient in vivo and 3-NT levels were increased in mitochondrial proteins. Liver mitochondria from mice fed the HFD for 16 weeks exhibited depressed state 3 respiration, uncoupled respiration, cytochrome c oxidase activity, and mitochondrial membrane potential. These findings indicate that chronic exposure to a HFD negatively affects the bioenergetics of liver mitochondria and this probably contributes to hypoxic stress and deleterious NO-dependent modification of mitochondrial proteins.
Mitochondrial Serine Acetyltransferase Functions as a Pacemaker of Cysteine Synthesis in Plant Cells
Authors: Haas Florian H. , Heeg Corinna , Queiroz Rafael , Bauer Andrea , Wirtz Markus , Hell Rüdiger 
Published: August 2008

AbstractCysteine (Cys) synthesis in plants is carried out by two sequential reactions catalyzed by the rate-limiting enzyme serine acetyltransferase (SAT) and excess amounts of O-acetylserine(thiol)lyase. Why these reactions occur in plastids, mitochondria, and cytosol of plants remained unclear. Expression of artificial microRNA (amiRNA) against Sat3 encoding mitochondrial SAT3 in transgenic Arabidopsis (Arabidopsis thaliana) plants demonstrates that mitochondria are the most important compartment for the synthesis of O-acetylserine (OAS), the precursor of Cys. Reduction of RNA levels, protein contents, SAT enzymatic activity, and phenotype strongly correlate in independent amiSAT3 lines and cause significantly retarded growth. The expression of the other four Sat genes in the Arabidopsis genome are not affected by amiRNA-SAT3 according to quantitative real-time polymerase chain reaction and microarray analyses. Application of radiolabeled serine to leaf pieces revealed severely reduced incorporation rates into Cys and even more so into glutathione. Accordingly, steady-state levels of OAS are 4-fold reduced. Decrease of sulfate reduction-related genes is accompanied by an accumulation of sulfate in amiSAT3 lines. These results unequivocally show that mitochondria provide the bulk of OAS in the plant cell and are the likely site of flux regulation. Together with recent data, the cytosol appears to be a major site of Cys synthesis, while plastids contribute reduced sulfur as sulfide. Thus, Cys synthesis in plants is significantly different from that in nonphotosynthetic eukaryotes at the cellular level.
RESEARCH VULNERABILITY: AN ILLUSTRATIVE CASE STUDY FROM THE SOUTH AFRICAN MINING INDUSTRY
Authors: HORN LYN 
Published: August 2008

ABSTRACTThe concept of ‘vulnerability’ is well established within the realm of research ethics and most ethical guidelines include a section on ‘vulnerable populations’. However, the term ‘vulnerability’, used within a human research context, has received a lot of negative publicity recently and has been described as being simultaneously ‘too broad’ and ‘too narrow’.1 The aim of the paper is to explore the concept of research vulnerability by using a detailed case study – that of mineworkers in post‐apartheid South Africa. In particular, the usefulness of Kipnis’s taxonomy of research vulnerability will be examined.2In recent years the volume of clinical research on human subjects in South Africa has increased significantly. The HIV and TB pandemics have contributed to this increase. These epidemics have impacted negatively on the mining industry; and mining companies have become increasingly interested in research initiatives that address these problems. This case study explores the potential research vulnerability of mineworkers in the context of the South African mining industry and examines measures that can reduce this vulnerability.
Insulin resistance in subjects with a history of thyrotoxic periodic paralysis (TPP)
Authors: Soonthornpun Supamai , Setasuban Worawong , Thamprasit Atchara 
Published: August 2008

SummaryBackground  Hyperinsulinaemia has been suggested as an important factor for developing hypokalaemic paralysis in patients with thyrotoxic periodic paralysis (TPP). Since hyperinsulinaemia is a common feature of insulin resistance, there may be a causal relationship between insulin resistance and TPP.Objective  To compare insulin sensitivity between subjects with a history of TPP and others with a history of thyrotoxicosis without periodic paralysis.Methods  Insulin sensitivity measured by euglycaemic hyperinsulinaemic clamp and 75‐g oral glucose tolerance test (OGTT) were performed nonselectively in 10 subjects with a history of TPP (TPP group) and 10 age‐ and sex‐matched subjects with a history of simple thyrotoxicosis (control group). All participants had euthyroidism and fasting plasma glucose of < 5·55 mmol/l at the time of the study.Results  Body mass index and waist circumference of the TPP group were higher than that of the control group. One of 10 (10%) subjects in the TPP group and 6 of 10 (60%) in the control group had BMI of < 23 kg/m2. Areas under the curve (AUC) of plasma glucose after OGTT were comparable, while the AUC of serum insulin of the TPP group was higher than in the control group. The TPP group had lower insulin sensitivity than the control group.Conclusion  The subjects with a history of TPP were more obese and had lower insulin sensitivity than those with a history of simple thyrotoxicosis. Insulin resistance with compensatory hyperinsulinaemia may be a key feature of the pathogenesis of TPP.
Characterization of asphaltene structure using atomic force microscopy
Authors: SABBAGHI S. , SHARIATY‐NIASSAR M. , AYATOLLAHI SH. , JAHANMIRI A. 
Published: August 2008

SummaryIn this study, at the first stage, asphaltene was extracted. The roughness of asphaltene coating at different rpm was studied using an image analysis confocal microscopy. The basics of quantum mechanics and statistical thermodynamics are used to predict the potential energy and the intermolecular forces of asphaltene molecules. The functional forms for the potential energy and intermolecular forces are evaluated. Our final goal is to be able to observe and determine the surface structures of asphaltene micelles with scanning probe microscopes. So, the focus of the work on these unusual molecules is to characterize their structure, dynamics and thermodynamics and to establish the relationship between these properties and petroleum fluid behaviour. The existence of various nanostructures of asphaltene in petroleum has been extensively discussed. A set of fitted data is used to check the validity of the calculated results. The good agreement between the proposed models and the data is promising.
A confident scale–space shape representation framework for cell migration detection
Authors: ZHANG K. , XIONG H. , ZHOU X. , YANG L. , WANG Y.‐L. , WONG S. T. C. 
Published: August 2008

SummaryAutomated segmentation of time‐lapse images is a method to facilitate the understanding of the intricate biological progression, e.g. cancer cell migration. To address this problem, we introduce a shape representation enhancement over popular snake models in the context of confident scale–space such that a higher level of interpretation can hopefully be achieved. Our proposed system consists of a hierarchical analytic framework including feedback loops, self‐adaptive and demand‐adaptive adjustment, incorporating a steerable boundary detail term constraint based on multiscale B‐spline interpolation. To minimize the noise interference inherited from microscopy acquisition, the coarse boundary derived from the initial segmentation with refined watershed line is coupled with microscopy compensation using the mean shift filtering. A progressive approximation is applied to achieve represented as a balance between a relief function of watershed algorithm and local minima concerning multiscale optimality, convergence and robust constraints. Experimental results show that the proposed method overcomes problems with spurious branches, arbitrary gaps, low contrast boundaries and low signal‐to‐noise ratio. The proposed system has the potential to serve as an automated data processing tool for cell migration applications.
Unravelling the structure of the lamellipodium
Authors: SMALL J.V. , AUINGER S. , NEMETHOVA M. , KOESTLER S. , GOLDIE K.N. , HOENGER A. , RESCH G.P. 
Published: August 2008

SummaryPushing at the cell front is the business of lamellipodia and understanding how lamellipodia function requires knowledge of their structural organization. Analysis of extracted, critical‐point‐dried cells by electron microscopy has led to a current dogma that the lamellipodium pushes as a branched array of actin filaments, with a branching angle of 70°, defined by the Arp2/3 complex. Comparison of different preparative methods indicates that the critical‐point‐drying‐replica technique introduces distortions into actin networks, such that crossing filaments may appear branched. After negative staining and from preliminary studies by cryo‐electron tomography, no clear evidence could be found for actin filament branching in lamellipodia. From recent observations of a sub‐class of actin speckles in lamellipodia that exhibit a dynamic behaviour similar to speckles in the lamella region behind, it has been proposed that the lamellipodium surfs on top of the lamella. Negative stain electron microscopy and cryo‐electron microscopy of fixed cells, which reveal the entire complement of filaments in lamellipodia show, however, that there is no separate, second array of filaments beneath the lamellipodium network. From present data, we conclude that the lamellipodium is a distinct protrusive entity composed of a network of primarily unbranched actin filaments. Cryo‐electron tomography of snap‐frozen intact cells will be required to finally clarify the three‐dimensional arrangement of actin filaments in lamellipodia in vivo.
Signal relay during chemotaxis
Authors: GARCIA G.L. , PARENT C.A. 
Published: August 2008

SummaryThe ability of cells to migrate in response to external cues, a process known as chemotaxis, is a fundamental phenomenon in biology. It is exhibited by a wide variety of cell types in the context of embryogenesis, angiogenesis, inflammation, wound healing and many other complex physiological processes. Here, we discuss the signals that control the directed migration of the social amoebae Dictyostelium discoideum both as single cells and in the context of group migration. This multi‐cellular organism has served as an excellent model system to decipher amoeboid‐like leukocyte migration and has played a key role in establishing signalling paradigms in the chemotaxis field. We envision that Dictyostelium will continue to bring forward basic knowledge as we seek to understand the mechanisms regulating group cell migration.