bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of altitude training on haematological variables in women volleyball players
Authors: Cueto-Martín B , de la Cruz-Márquez J C , de la Cruz-Campos J C , de la Cruz-Campos A
Published: April 2011

Background

Athletes from many endurance disciplines include altitude training in their yearly training programme. In volleyball, it is necessary to clarify the haematological benefits and improvement in sports performance.

Objective

To investigate the influence of moderate altitude on haematological variables in a women's volleyball team (Honor Division – Spain).

Design and setting

We assessed 14 elite female volleyball players for two weeks in normoxia (640 m above sea level), two weeks in relative hypoxia (2450 m, at the High Performance Center of Sierra Nevada, Granada, Spain) and two final weeks in normoxia again, during the volleyball preseason (August–September).

Participants

14 women (mean age 23±2.8 years; height: 184.9±6.9 cm; weight: 73.1±6.2 kg). All players who started the study completed it. None were taking dietary supplements, vitamins or exogenous iron. During the study, all players menstruated.

Interventions

The volleyball players trained twice daily (3 h/season). Blood samples were taken at 7-day intervals in normoxia and 72 h in hypoxia. Economy of effort was evaluated by the relationship between oxygen intake (Vo2) and running speed on a treadmill using sport-specific protocols. Blood samples were taken monthly during volleyball season.

Independent Variable: Altitude.

Dependent Variables: Haematological and VO2intake.

Results

Higher levels of haemoglobin (14.1±1.2 g/dl) and hematocrit (42.7±2.2%) were obtained at normoxia prealtitude, while the lowest levels were obtained in the first week post-altitude (12.9±1.8 g/dl; 38.9±2.3% respectively; p<0.05). After the stay at altitude, oxygen intake was increased (48.1±1.5 to 51.4±2.3 ml/kg/min; p<0.05).

Conclusions

2 weeks of moderate hypoxia improved the maximum oxygen intake but not the haemoglobin or hematocrit levels.
Long-term Holter ECG monitoring of volleyball players
Authors: de la Cruz-Campos J C , de la Cruz-Márquez J C , Cueto-Martín B , de la Cruz-Campos A
Published: April 2011

Background

The resting ECG can detect many cardiac abnormalities, but high levels of training to which athletes are subjected can trigger episodes of abnormal heart function, which should be evaluated by means of long-term records.

Objective

The purpose of the study was to detect the frequency and nature of rhythmic alterations in volleyball players during the late recovery period following a match.

Design

Retrospective study.

Setting and participants

12 volleyball players, volunteers, from 18–32 years old (mean: 24.5±1.2 years), members of a First National Division team. All were declared fit for volleyball and had no ECG abnormalities. The subjects underwent Holter ECG recording before and immediately after a match. The Holter used was NORAV DXP-1000 model.

Interventions

Both the day before and after a match, the players did not train but did all work or academic activities normally. They were instructed to record their times of sleep and activity. Dependent variables: pertaining to heart rate, rhythm and ST space. Independent variable: physical exercise (match).

Results

The average pre/post-match heart rates were 68.3±8.9 bpm when awake; 64.1±5.6 (p<0.01) and 62.8±7.7; 61.2±8.5 (p<0.01) when sleeping. Both before and after the match, 11 players (91%) had a mild or pronounced respiratory sinus arrhythmia. Isolated atrial or ventricular premature contractions were observed in 1 (8.3%), first-degree intermittent A-V blocks and second-degree A-V blocks with Wenckebach periods were observed in 1, high T-waves were found in 5 (41.6%), and high take-off of ST segments were found in 6 (50%).

Conclusions

After the match, there are fewer pulsations recorded, there are more bradycardic rhythms and there are fewer arrhythmic events.
Electrocardiographic profile of volleyball players
Authors: de la Cruz-Márquez J C , Cueto-Martín B , de la Cruz-Campos J C , de la Cruz-Campos A
Published: April 2011

Background

The 12-lead ECG is not only necessary for diagnosing the sports aptitude of players, but it also provides information on their training condition and cardiovascular adaptations to exercise.

Objective

To determine the electrocardiographic adaptations of high-level volleyball players and relate them to their level of training.

Design

Retrospective study over the course of 18 years, from 1992 to 2009. We analyzed the ECGs taken at the start of each season as part of routine medical test. We analyzed 1080 ECGs (15 players/18 years/4 teams – two male and two female).

Setting and participants

Male and female youth and Honor Division teams from the same club. 180 women (94 youth, 86 senior) and 210 men (126 youth, 84 senior) (mean age, height, weight).

Intervention

In August–September of each season, a resting ECG was taken for each player to determine pre-competitive fitness. Independent variables: sex, age, years of training. Dependent variables: P waves, QRS, T in duration and voltage and ECG evaluation (axes).

Results

ECG/player Average: 5.6±1.9, FC resting: 66.3±3 bpm. Left ventricular hypertrophy: 38.95%±8.9; Right ventricular hypertrophy: 12.77%±3.4. Right Bundle Branch Block: 25.64%±8.3. Participants who required echocardiography: eight players: ST segment depression. five players: Inverted or flattened T wave in two or more leads. Three men and two women: Corrected QT interval prolongation in heart rate (QTc)> 0.44 s in men and> 0.46 s in women. Echocardiography ruled out organic disease. There were no differences in terms of years of training or level.

Conclusions

Electrocardiographic adaptations in volleyball are similar to those in the literature for team sports. There was no pathological study and all were declared fit for the high-level sport.
The age and gender effects on heart rate in children school volleyball players from Bosnia and Herzegovina
Authors: Masala A , Bajraktarevic A , Miokovic M , Omerovic M , Rovcanin A , Sporisevic L
Published: April 2011

Background

Volleyball is a fun sport for children that is easy to learn and can be played in a gym, at the beach, or on grass. Playing volleyball help improve child heart work, flexibility, balance and coordination. Some schools have volleyball teams for boys and girls. Heart rates can improve sports exercise and volleyball can make children stronger and healthier.

Objective

The purpose of this study was to examine accountability paediatrics systems operating in youth volleyball training sessions and to understand how those systems vary according to the instructional tasks and the nature of the information provided by paediatricians.

Design, setting and participants

The ECG recording was performed for 5 min at rest in seated, supine or supine with elevated legs body position on different days in girl and boy school volleyball players. Measurements were undertaken in a quiet room, air temperature ranging from 21 to 22°C, after and before volleyball games. The data was analyzed for 40 female and 40 male volleyball players ranging in age from 12 to 16 years, and other equal players and athletes in other sports of the same age and gender.

Methods

Systematic medical observation strategies were used to describe and analyse paediatric tasks for heart rates presentation and task volleyball players in schools during paediatrics examinations. Statistical analyses were performed using the Sigmastat Programme 3.0 for windows package during period 2005–2009 in school players teams in Bosnia and Herzegovina.

Main outcome measurement

Young female volleyball players are more vulnerable to sport injuries but similiar heart rates stabilizing works after volleyball games comparing than their boys counterparts.

Results

Heart rates after volleyball games and exercise were lower and better than other sports groups in both volleyball groups for girls and boys, too, without difference.

Conclusions

Further research needs to address issues of paediatricians' knowledge and conceptions related to volleyball instruction for heart works improvement. No differences were noted between heart rates after exercise in boys and girls volleyball school players, but better heart rates were observed in older age volleyball players when compared to other athletes such as tennis players and soccer or basketball players.
Factor structure differences of indicators for evaluating isometric leg extensors explosive force in female volleyball athletes and different trained female population
Authors: Ivanović J , Dopsaj M , Nešić G
Published: April 2011

Background

Adequate leg extensors preparation is highly important especially in volleyball which involve several jumping techniques. Values of developed force in the function of time generated during the isometric (static) muscle contraction, with it's own F-t curve characteristics are the fundamental data on contractile ability.

Objective

Factor structure differences of indicators for evaluating isometric leg extensors explosive force (RFDLEGEXTISO) regarding different trained female population will be examined in this research.

Setting and participants

Sample included 50 examinees: top level female volleyball players (Elite N=20), unspecific trained female athletes (Nonspec N=18) and untrained female (Control N=12).

Methods

In order to assess characteristics of the F-t isometric leg extensors force, tensiometric probe and standardized ‘seating leg extension’ test were used. The measurement range was defined by 11 variables regarding the contractile characteristics of the leg extensors isometric muscle force at the level of 100, 50, 30, 50–100% of maximal force (FmaxLEGEXTISO): rate of force development (RFD) analysed from the aspect of absolute and relative (allometric) values – the indicators of basic (RFDBASICLEGEXTISO, RFDallomLEGEXTISO), specific (RFD50%LEGEXTISO, RFDallomLEGEXTISO50%), special (RFD30%LEGEXTISO, RFDallomLEGEXTISO30%), at 50–100% (RFD50–100%LEGEXTISO) level of RFD, Synergy Index as a criterion of relation between RFDLEGEXTISO and FmaxLEGEXTISO at the basic level of 100% – IndexSNGBASIC, specific level of 50% – IndexSNGSPEC and special level of 30% – IndexSNGSPECIJ.

Results

Factor analysis set apart two factors in all the observed groups, which have explained 96.491% in Elite, 95.502% in Nonspec, 96.512% in Control of valid variance. The differences in structure and in number of parameters for separated factors were established especially between tested trained and untrained population. They can be explained with differences in muscle tissue and maximal nervous activation of muscles during the specific training, that is, adaptation to specific training.

Conclusions

The obtained results can possibly be used as an indicator of potential of leg explosiveness and jumping performances in volleyball players selection.
Study of extensor and flexor musculature in the knees of male and female volleyball players
Authors: Rodríguez-Ruiz D , Rodríguez-Matoso D , Quiroga M E , Sarmiento S , Da Silva-Grigoletto M E
Published: April 2011

Objective

The aim of the present study was to analyse differences in muscle response and mechanical characteristics of the vastus medialis (VM), rectus femoris (RF), vastus lateralis (VL) and biceps femoris (BF) in elite volleyball players of both sexes using tensiomyography (TMG).

Setting

47 players of nine nationalities playing in teams belonging to the men's and women's Spanish Superleagues (elite division) were assessed.

Participants

22 women (age 24.59±4.27 years; weight 72.14±10.06 kg; height 178.40±8.50 cm) and 25 men (age 25.04±4.29 years; weight 88.76±9.07 kg; height 194.71±7.84 cm).

Methods

TMG was used to assess muscular response, muscular mechanical characteristics, and gender differences. For this purpose, the following variables were analysed: maximum radial displacement of muscle belly or maximum deformation (Dm), and normalised response speed (Vrn).

Results

The findings show, both in men and women, a higher normalised response speed (Vrn) score in the VL and VM compared to the RF and BF. A marked lateral symmetry of maximum radial deformation or displacement of the muscle belly (Dm) was also observed in the musculature of the lower limbs, with no statistically-significant differences being detected in either men or women. There were, however, clear differences in terms of muscle response between male and female volleyball players: women displayed a more pronounced difference in the Vrn of the musculature responsible for extension (VM, RF and VL) and flexion (BF) of the knee joint than men.

Conclusions

TMG proved to be a highly sensitive tool for detecting changes in lower limb muscle activity.
Injury prediction in volleyball players.
Authors: de la Cruz-Márquez J C , Cueto-Martín B , de la Cruz-Campos J C , de la Cruz-Campos A
Published: April 2011

Background

An accentuated Quadriceps (Q) angle, genu valgum, flat feet, femoral anteversion, lumbar hyperlordosis and lower limb dysmetria can be factors favouring the occurrence of injuries.

Objective

To determine what degrees of Q angle can be tolerated by and what corrector guidelines can be established for volleyball players.

Design

A Q angle analysis was performed on 36 female and 41 male volleyball players from a Spanish honour division team for 5 years, as well as a measurement of weight distribution on a balance platform. We determined the injuries suffered during each season and their relation to the physical activity.

Setting and participants

44 females and 46 males (females: mean age 22±3.4 years; height: 182.3±5.7 cm; weight: 71.9±4.1 kg; males: 23±3.3 and; 188.2±3.8 cm; 84.8±6.9 kg) who were on the team during the 5-year period of study. Eight females and five males did not complete the study.

Interventions

A logistic regression analysis was performed to determine the influence of anthropometric factors on the occurrence of injuries.

Independent Variables: Anthropometric measures, balance, minutes of training.

Dependent: Injuries.

Results

Females: In the right lower limb, the Q angle average is 14.14°±1.8 degrees, while in the left lower limb it is 14.97°±1.1 (p<0.01). Males: Right Q angle: 13.1°±2.2; Left: 13.75°±1.7 (p<0.01). Sharp Left Q angle favours the occurrence of lower limb and back injuries. There is no connection to practical exposure.

Conclusions

We formulated a logistic regression equation that predicts the occurrence of injuries. Degree of satisfaction: 75% (females), 85% (males). 1/1+e-(0.757•LQA−0.647•DTT)2. (e: Natural Logarithm e; LQA: Left Q angle; DTT: Differences in thigh thickness).
An analysis of volleyball injuries in female athletes in grades nine through twelve
Authors: Yasher K R , Liller K , Wong S , Jang S , Morris B J , Konin J G
Published: April 2011

Background

Participation in women's sports has increased over the years, potentially leading to an increased exposure rate for injury. Identifying the prevalence and severity of specific injuries associated with volleyball can lead to effective injury prevention interventions and educational programs.

Objective

To analyze injury trends associated with women's volleyball for grade 9–12.

Design

A retrospective analysis of medical records collected by certified athletic trainers at 10 high schools was performed over a three year period from 2006–2009.

Setting

Data was collected via web based software in the USA for volleyball athletes in grades 9–12.

Participants

Participants included female volleyball players in grades 9–12 who participated in a sanctioned high school volleyball athletic season.

Intervention

Injury definitions were standardized prior to the medical documentation, and were limited to self-reporting by the athletes or direct observation by the athletic trainer. Injury is defined by something that results from participation in competition or practice, requires medical attention and results in restriction and or modification in participation for one or more days beyond the day of injury.

Main outcome measurements

Measurements were recorded based upon each exposure, defined as a single practice or game session per player.

Results

A total of 30 366 exposures were recorded, with just 31documented injuries. 35.5% of the documented injuries involved the ankles followed by knees and thumbs with 13%. 66.67% of injuries occurred during non-contact skills practices, 24% occurred to middle blockers, 19% occurred due to jumping and landing and 26% occurred toward the end of practice. For every 1000 exposures, 0.964 injuries occurred during a practice session and 0.698 injuries occurred during a match.

Conclusions

Volleyball injuries in females in grades 9–12 appear low overall in prevalence and severity. Future studies for volleyball participation are encouraged to assess different age groups, gender, and other variables.
Volleyball injuries: a survey of injuries of the Portuguese Female National Team
Authors: Massada M , Aido R , Magalhaes C , Puga N
Published: April 2011

Background

Volleyball is a dynamic sport, presenting a high number of movement injuries. Analysis of injury prevalence is crucial for the development of prevention programmes.

Objectives

To estimate the overall incidence of acute and overuse volleyball injuries in the Female National Team during the 2008–2009 season.

Design

Prospective recording of newly incurred injuries.

Setting and participants

Female Portuguese National Team Participants: 32 female volleyball players participated in the study and were followed prospectively during a whole season.

Interventions

All players completed a questionnaire on demographic variables, sports participation, use of preventive measures, and previous injuries. Volleyball exposure during training and matches was recorded for each individual player by the team's physical therapist (PT) on a weekly exposure form. In case of injury the PT provided the injured player with an injury registration form, which had to be completed within one week after the onset of injury.

Main outcome measurements

The incidence and burden of injuries and factors associated with injury.

Results

100 injuries were reported, resulting in an overall injury incidence of 2.6 injuries/1000 h. The incidence of acute injuries was 2.0/1000 h. Ankle sprains (n=41) accounted for most of the acute injuries, and 31 (75%) of all players with an ankle sprain reported a previous ankle sprain. The majority of injuries occurred during blocking or spiking. 25 overuse injuries were reported. The overall incidence of overuse injuries was 0.6/1000 h; the back and the shoulder were the most common sites.

Conclusions

Ankle sprain is the most common injury in volleyball, accounting for 41% of all volleyball related injuries. Previous injury seems to be an important risk factor for an ankle sprain. Injury prevention programmes should focus on ankle sprains and concentrate on players with previous ankle sprains.
Systematic sports medical prophylactic evaluations in the countries of the former USSR
Authors: Mustafins P , Landyr A , Schybria I , Istomina J , Gurevich T
Published: April 2011

Background

Periodic health evaluations for athletes are widely discussed in the sports medical literature, and are intended to screen for underlying cardiovascular disease, identify sports injury risk factors and posture disturbances, as well as exercise induced physiological conditions.

Objective

To review the systematic the athletes' periodic health evaluations in the territories of the former USSR.

Participants

Selected sports medicine outpatient centres (SMC) and sports medicine physicians in Russia and Estonia.

Methods

We reviewed the structure and outcome of the yearly visits at the participating SMCs, and the sports medicine educational curriculum at the University of Tartu in Estonia.

Results

Periodic health evaluations for athletes have been conducted since 1949. The system integrates the facilities (sports medical centers) and the education of the sports physicians. Outpatient check ups of the athletes coming from all the levels of sport were conducted at the SMC. At one time over 500 SMCs existed, involving sports physicians, surgeons, neurologists, otolaryngologists, ophthalmologists, dentists and gynaecologists. Anthropometric data were collected, in addition to EKG, physical work capacity testing, and laboratory measurements – depending on the athletes' level and on a kind of sport. As a current sample, an annual amount of visits to the physicians per single regional SMC was 99 601 (Yekaterinburg Sports medical centre (Russia), prophylactic check ups and treatments, year 2009). The specific program of sports physician education at the University of Tartu in Estonia began in 1959. The program comprised the standard MD curriculum plus additional courses on sports theory, sports physiology, sports cardiology, exercise stress testing, sports injury, and rehabilitation. A total of 818 physicians were trained through 1995 – when the program was closed after the breakup of the USSR. Although still in existence in Russia, in many other countries the system has been downscaled or phased out.

Conclusions

To our knowledge, the system described was the largest state-sponsored sports medical prophylactic approach in the world. Although in many instances there was no proof of the cost effectiveness of this approach, many elements of the athletes' periodic health evaluations and education of the sports physicians we describe should be considered as precursors of today's modern sports medicine programs.
Survival of the fattest: unexpected findings about hyperglycaemia and obesity in a population based study of 75-year-olds
Authors: Nilsson Göran , Hedberg Pär , Öhrvik John
Published: April 2011

Objective

To study the relationship between body mass index (BMI) and mortality among 75-year-olds with and without diabetes mellitus type 2 (DM) or impaired fasting glucose (IFG).

Design

Prospective population-based cohort study with a 10-year follow-up.

Participants

A random sample of 618 of the 1100 inhabitants born in 1922 and living in the city of Västerås in 1997 were invited to participate in a cardiovascular health survey; 70% of those invited agreed to participate (432 individuals: 210 men, 222 women).

Outcome measures

All-cause and cardiovascular mortality.

Results

163 of 432 (38%) participants died during the 10-year follow-up period. The prevalence of DM or IFG was 41% (35% among survivors, 48% among non-survivors). The prevalence of obesity/overweight/normal weight/underweight according to WHO definitions was 12/45/42/1% (14/43/42/1% among survivors, 9/47/42/2% among non-survivors). The hazard rate for death decreased by 10% for every kg/m2increase in BMI in individuals with DM/IFG (HR 0.91, 95% CI 0.86 to 0.97; p=0.003). After adjustment for sex, current smoking, diagnosed hypertension, diagnosed angina pectoris, previous myocardial infarction and previous stroke/transient ischaemic attack, the corresponding decrease in mortality was 9% (HR 0.92, 95% CI 0.86 to 0.99; p=0.017). These findings remained after exclusion of individuals with BMI<20 or those who died within 2-year follow-up. In individuals without DM/IFG, BMI had no effect on mortality (HR 1.01, 95% CI 0.95 to 1.07; p=0.811). The HR for BMI differed significantly between individuals with and without DM/IFG (p interaction=0.025). The increased all-cause mortality in individuals with DM/IFG in combination with lower BMI was driven by cardiovascular death.

Conclusion

High all-cause and cardiovascular mortality was associated with lower BMI in 75-year-olds with DM/IFG but not in those without DM/IFG. Further studies on the combined effect of obesity/overweight and DM/IFG are needed in order to assess the appropriateness of current guideline recommendations for weight reduction in older people with DM/IFG.
A DYNAMIC PROGRAMMING HEURISTIC FOR RETAIL SHELF SPACE ALLOCATION PROBLEM
Authors: GAJJAR HASMUKH K. , ADIL GAJENDRA K.
Published: April 2011

Shelf space allocation to products greatly impacts the profitability in a retail store. In this paper, we consider a retail shelf-space allocation problem where retailer wishes to allocate the available spaces of different shelves to a large number of products considering direct space elasticity in the product's demand. There is a great interest to develop efficient heuristics due to NP-hard nature of this problem. We propose a dynamic programming heuristic (DPH) to obtain near optimal solution in a reasonable time to solve this problem. The empirical results found that DPH obtained near optimal solutions for randomly generated instances of problems with size (products, shelves) varying from (100, 30) to (200, 50) within a few seconds of CPU time. The performance of DPH is benchmarked against an existing local search heuristic (LSH). It was found that DPH takes substantially less CPU time and attains a solution close to that obtained by LSH. Thus, DPH has great potential to solve the problem of realistic size within reasonable time. The proposed DPH is also applied to a case of an existing retail store.
TABU SEARCH FOR MULTIPROCESSOR SCHEDULING: APPLICATION TO HIGH LEVEL SYNTHESIS
Authors: SEVAUX MARC , SINGH ALOK , ROSSI ANDRÉ
Published: April 2011

This paper describes a tabu search approach for a multiprocessor scheduling problem, where a list of jobs has to be scheduled on identical parallel processors. Each job in the list has a release date, a due date, a processing time and a set of predecessors. The objective is to minimize the number of processors used while respecting the constraints imposed by release dates, due dates and precedences. Two versions of this problem are considered here, in the first one precedence constraints are relaxed, they are taken into account in the second one. The proposed method is used to solve High Level Synthesis problem instances. The results show the effectiveness of our approach for both versions of the problem. A comparison with an exact method is also conducted.
A DECISION MODEL FOR SELECTING THIRD-PARTY REVERSE LOGISTICS PROVIDERS IN THE PRESENCE OF BOTH DUAL-ROLE FACTORS AND IMPRECISE DATA
Authors: SAEN REZA FARZIPOOR
Published: April 2011

This paper introduces a model for dealing with selecting third-party reverse logistics (3PL) providers in the presence of both dual-role factors and imprecise data. The proposed model is based on data envelopment analysis (DEA). A numerical example demonstrates the application of the proposed method.
HEURISTICS WITH STOCHASTIC NEIGHBORHOOD STRUCTURES FOR TWO-DIMENSIONAL BIN PACKING AND CUTTING STOCK PROBLEMS
Authors: CHAN T. M. , ALVELOS FILIPE , SILVA ELSA , DE CARVALHO J. M. VALÉRIO
Published: April 2011

This paper proposes a heuristic with stochastic neighborhood structures (SNS) to solve two-stage and three-stage two-dimensional guillotine bin packing and cutting stock problems. A solution is represented as a sequence of items which are packed into existing or new stacks, shelves or bins according to previously defined criteria. Moreover, SNS comprises three random neighborhood structures based on modifying the current sequence of items. These are called cut-and-paste, split, and swap blocks and are applied one by one in a fixed order to try to improve the quality of the current solution. Both benchmark instances and real-world instances provided by furniture companies were utilized in the computational tests. Particularly, all benchmark instances are bin packing instances (i.e., the demand of each item type is small), and all real-world instances are classified into bin packing instances and cutting stock instances (i.e., the demand of each item type is large). The computational results obtained by the proposed method are compared with lower bounds and with the solutions obtained by a deterministic Variable Neighborhood Descent (VND) meta-heuristic. The SNS provide solutions within a small percentage of the optimal values, and generally make significant improvements in cutting stock instances and slight to moderate improvements in bin packing instances over the VND approach.
AN AUGMENTED SPACE-BASED CLUSTER COHERENT POTENTIAL APPROXIMATION: APPLICATION TO CuAu AND NiAl ALLOYS
Authors: RAHAMAN MOSHIOUR , MOOKERJEE ABHIJIT
Published: April 2011

We use cluster generalization of the coherent potential approximation in the tight-binding linear muffin-tin orbital method to account for the effect of the local environment on electronic and magnetic properties of substitutional random alloys. This theory combines the augmented space formalism and conventional tight-binding linear muffin-tin orbital methods. In particular, we shall apply the technique to the bcc-based NiAl and fcc-based CuAu alloys and also compare with other approaches.
AN EXACT MAP FOR A CHAOTIC BILLIARD
Authors: MIKOSS I. , GARCÍA P.
Published: April 2011

An exact map for Sinai's billiard with maximal central scatterer has been deduced from geometrical principles. Using this map a simple numerical method has been implemented for the search of periodic orbits. Results that seem to be useful in classical as quantum chaos are shown.
MODELING AND SCALING OF THE DISTRIBUTION OF TRADE AVALANCHES IN A STOCK MARKET
Authors: KIM HYUN-JOO
Published: April 2011

We study the trading activity in the Korea Stock Exchange by considering trade avalanches. A series of successive trading with small trade time interval is regarded as a trade avalanche of which the size s is defined as the number of trade in a series of successive trades. We measure the distribution of trade avalanches sizes P(s) and find that it follows the power-law behavior P(s) ~ s-α with the exponent α ≈ 2 for two stocks with the largest number of trades. A simple stochastic model which describes the power-law behavior of the distribution of trade avalanche size is introduced. In the model it is assumed that the some trades induce the accompanying trades, which results in the trade avalanches and we find that the distribution of the trade avalanche size also follows power-law behavior with the exponent α ≈ 2.
ON THE LABEL GRAPHOIDAL COVERING NUMBER-II
Authors: HAMID I. SAHUL , ANITHA A.
Published: April 2011

Let G = (V, E) be a graph with p vertices and q edges. An acyclic graphoidal cover of G is a collection ψ of paths in G which are internally disjoint and covering each edge of the graph exactly once. Let f : V → {1, 2, …, p} be a labeling of the vertices of G. Let ↑Gf be the directed graph obtained by orienting the edges uv of G from u to v provided f(u) < f(v). If the set ψf of all maximal directed paths in ↑Gf, with directions ignored, is an acyclic graphoidal cover of G, then f is called a graphoidal labeling of G and G is called a label graphoidal graph and ηl = min {|ψf|: f is a graphoidal labeling of G} is called the label graphoidal covering number of G. An orientation of G in which every vertex of degree greater than 2 is either a sink or a source is a graphoidal orientation. In this paper we characterize graphs for which (i) ηl = ηa and (ii) ηl = Δ. Also, we discuss the relation between graphoidal labeling and graphoidal orientation.
ALGORITHMS FOR MINIMUM CONNECTED CAPACITATED DOMINATING SET PROBLEM
Authors: SHANG WEIPING , WANG XIUMEI
Published: April 2011

Connected dominating set (CDS) has been proposed as the virtual backbone to alleviate the broadcasting storm in wireless sensor network. Most recent research has extensively focused on the construction of connected dominating set. However, the nodes in the CDS need to dominate all its neighbors, and then some nodes cover a large number of neighboring nodes. Therefore, it is desirable to construct a capacitated dominating set, each node can dominate only a certain number of neighbors. In this paper, we study capacitated dominating set and connected capacitated dominating set, and propose two approximation algorithms with small approximation ratios.
THE HYPER-WIENER INDEX OF THE kth POWER OF A GRAPH
Authors: ZHANG WEIJUAN , WU BAOYINDURENG , AN XINHUI
Published: April 2011

The k th power of a graph G, denoted by Gk, is a graph whose vertex set is V(G), two distinct vertices being adjacent in Gk if and only if their distance in G is at most k. The hyper-Wiener index WW(G) of a graph G is defined as [Formula: see text], where dG(u,v) is the distance between vertices u and v in G. In this paper, the bounds on the hyper-Wiener index of the graph Gk are given. The Nordhaus–Gaddum-type inequality for the hyper-Wiener-index of the graph Gk is also presented.
A NOTE ON TRICYCLIC GRAPHS WITH MINIMUM DEGREE DISTANCE
Authors: ZHU WEI , HU SHENGBIAO , MA HAICHENG
Published: April 2011

In this paper, we determine all the extremal tricyclic graphs with minimum degree distance.
THE UPPER AND LOWER INDEPENDENCE NUMBER OF GRAPHS
Authors: MARIMUTHU G. , SARASWATHY M. SIVANANDHA , MAHESHWARI G. UMA
Published: April 2011

In this paper, we introduce the concept called upper and lower independence number of a graph. The amount of independenceness of a vertex is calculated first. With the help of independenceness of vertices, we find the independence number of a graph. The main focus of this paper is to extend the dominating chain ir (G) ≤ γ(G) ≤ i(G) ≤ β0(G) ≤ Γ(G) ≤ IR (G), mentioned in [Haynes, Hedetniemi and Slater, Fundamentals of Domination in Graphs (Marcel Dekker, New York, 1998)].
ON CHARACTERISTIC AREA OF STEINER TREE
Authors: WU WEILI , ZHONG JIAOFEI
Published: April 2011

We present a definition of characteristic area and inner spanning tree to accommodate the proof of Du and Hwang for Gilbert–Pollak conjecture on the Steiner ratio in the Euclidean plane.
ON THE NULL-SPACES OF BICYCLIC SINGULAR GRAPHS
Authors: NATH MILAN
Published: April 2011

In [M. Nath and B. K. Sarma, On the null-spaces of unicyclic and acyclic graphs, Linear Algebra Appl.427 (2007) 42–54], Nath and Sarma gave an algorithm to find a basis for the null-space of a graph G when G is singular acyclic or unicyclic. In this paper, we find a basis for the null-space of G when G is a bicyclic singular graph.
ON THE EXISTENCE OF NON-ABELIAN (210, 77, 28), (336, 135, 54) AND (496, 55, 6) DIFFERENCE SETS
Authors: OSIFODUNRIN ADEGOKE S.
Published: April 2011

Lander [Symmetric Design: An Algebraic Approach, London Mathematical Society Lecture Note Series, Vol. 74 (Cambridge University Press, Cambridge, 1983)] showed that some abelian (v, k, λ) difference sets do not exist in some groups of order v and listed some parameters of difference sets that were open for small values of k (k ≤ 50). Various authors have since studied the open cases and have either constructed the difference sets when they exist or proved their non-existence. Using restrictions imposed by the underlying normal subgroups of groups, algebraic number theory, group representations and rational idempotents of the group ring, we rule out the existence of (496, 55, 6) difference sets and show that non-abelian (210, 77, 28) and (336, 135, 54) difference sets do not exist in most groups of 210 and 336, respectively.
Effects of alcohol septal ablation on coronary microvascular function and myocardial energetics in hypertrophic obstructive cardiomyopathy
Authors: Timmer Stefan A. J. , Knaapen Paul , Germans Tjeerd , Dijkmans Pieter A. , Lubberink Mark , ten Berg Jurrien M. , ten Cate Folkert J. , Rüssel Iris K. , Götte Marco J. W. , Lammertsma Adriaan A. , van Rossum Albert C.
Published: April 2011

This study investigated the effects of alcohol septal ablation (ASA) on microcirculatory function and myocardial energetics in patients with hypertrophic cardiomyopathy (HCM) and left ventricular outflow tract (LVOT) obstruction. In 15 HCM patients who underwent ASA, echocardiography was performed before and 6 mo after the procedure to assess the LVOT gradient (LVOTG). Additionally, [15O]water PET was performed to obtain resting myocardial blood flow (MBF) and coronary vasodilator reserve (CVR). Changes in LV mass (LVM) and volumes were assessed by cardiovascular magnetic resonance imaging. Myocardial oxygen consumption (MV̇o2) was evaluated by [11C]acetate PET in a subset of seven patients to calculate myocardial external efficiency (MEE). After ASA, peak LVOTG decreased from 41 ± 32 to 23 ± 19 mmHg ( P = 0.04), as well as LVM (215 ± 74 to 169 ± 63 g; P < 0.001). MBF remained unchanged (0.94 ± 0.23 to 0.98 ± 0.15 ml·min−1·g−1; P = 0.45), whereas CVR increased (2.55 ± 1.23 to 3.05 ± 1.24; P = 0.05). Preoperatively, the endo-to-epicardial MBF ratio was lower during hyperemia compared with rest (0.80 ± 0.18 vs. 1.18 ± 0.15; P < 0.001). After ASA, the endo-to-epicardial hyperemic (h)MBF ratio increased to 1.03 ± 0.26 ( P = 0.02). ΔCVR was correlated to ΔLVOTG ( r = −0.82; P < 0.001) and ΔLVM ( r = −0.54; P = 0.04). MEE increased from 15 ± 6 to 20 ± 9% ( P = 0.04). Coronary microvascular dysfunction in obstructive HCM is at least in part reversible by relief of LVOT obstruction. After ASA, hMBF and CVR increased predominantly in the subendocardium. The improvement in CVR was closely correlated to the absolute reduction in peak LVOTG, suggesting a pronounced effect of LV loading conditions on microvascular function of the subendocardium. Furthermore, ASA has favorable effects on myocardial energetics.
Influence of phase I duration on phase II V̇o2 kinetics parameter estimates in older and young adults
Authors: Murias Juan M. , Spencer Matthew D. , Kowalchuk John M. , Paterson Donald H.
Published: April 2011

Older adults (O) may have a longer phase I pulmonary O2 uptake kinetics (V̇o2p) than young adults (Y); this may affect parameter estimates of phase II V̇o2p. Therefore, we sought to: 1) experimentally estimate the duration of phase I V̇o2p (EE phase I) in O and Y subjects during moderate-intensity exercise transitions; 2) examine the effects of selected phase I durations (i.e., different start times for modeling phase II) on parameter estimates of the phase II V̇o2p response; and 3) thereby determine whether slower phase II kinetics in O subjects represent a physiological difference or a by-product of fitting strategy. V̇o2p was measured breath-by-breath in 19 O (68 ± 6 yr; mean ± SD) and 19 Y (24 ± 5 yr) using a volume turbine and mass spectrometer. Phase I V̇o2p was longer in O (31 ± 4 s) than Y (20 ± 7 s) ( P < 0.05). In O, phase II τV̇o2p was larger ( P < 0.05) when fitting started at 15 s (49 ± 12 s) compared with fits starting at the individual EE phase I (43 ± 12 s), 25 s (42 ± 10 s), 35 s (42 ± 12 s), and 45 s (45 ± 15 s). In Y, τV̇o2p was not affected by the time at which phase II V̇o2p fitting started (τV̇o2p = 31 ± 7 s, 29 ± 9 s, 30 ± 10 s, 32 ± 11 s, and 30 ± 8 s for fittings starting at 15 s, 25 s, 35 s, 45 s, and EE phase I, respectively). Fitting from EE phase I, 25 s, or 35 s resulted in the smallest CI τV̇o2p in both O and Y. Thus, fitting phase II V̇o2p from (but not constrained to) 25 s or 35 s provides consistent estimates of V̇o2p kinetics parameters in Y and O, despite the longer phase I V̇o2p in O.
Pharmacological glycerol-3-phosphate acyltransferase inhibition decreases food intake and adiposity and increases insulin sensitivity in diet-induced obesity
Authors: Kuhajda Francis P. , Aja Susan , Tu Yajun , Han Wan Fang , Medghalchi Susan M. , El Meskini Rajaa , Landree Leslie E. , Peterson Jonathan M. , Daniels Khadija , Wong Kody , Wydysh Edward A. , Townsend Craig A. , Ronnett Gabriele V.
Published: April 2011

Storage of excess calories as triglycerides is central to obesity and its associated disorders. Glycerol-3-phosphate acyltransferases (GPATs) catalyze the initial step in acylglyceride syntheses, including triglyceride synthesis. We utilized a novel small-molecule GPAT inhibitor, FSG67, to investigate metabolic consequences of systemic pharmacological GPAT inhibition in lean and diet-induced obese (DIO) mice. FSG67 administered intraperitoneally decreased body weight and energy intake, without producing conditioned taste aversion. Daily FSG67 (5 mg/kg, 15.3 μmol/kg) produced gradual 12% weight loss in DIO mice beyond that due to transient 9- to 10-day hypophagia (6% weight loss in pair-fed controls). Continued FSG67 maintained the weight loss despite return to baseline energy intake. Weight was lost specifically from fat mass. Indirect calorimetry showed partial protection by FSG67 against decreased rates of oxygen consumption seen with hypophagia. Despite low respiratory exchange ratio due to a high-fat diet, FSG67-treated mice showed further decreased respiratory exchange ratio, beyond pair-fed controls, indicating enhanced fat oxidation. Chronic FSG67 increased glucose tolerance and insulin sensitivity in DIO mice. Chronic FSG67 decreased gene expression for lipogenic enzymes in white adipose tissue and liver and decreased lipid accumulation in white adipose, brown adipose, and liver tissues without signs of damage. RT-PCR showed decreased gene expression for orexigenic hypothalamic neuropeptides AgRP or NPY after acute and chronic systemic FSG67. FSG67 given intracerebroventricularly (100 and 320 nmol icv) produced 24-h weight loss and feeding suppression, indicating contributions from direct central nervous system sites of action. Together, these data point to GPAT as a new potential therapeutic target for the management of obesity and its comorbidities.
Effect of a 5-HT1Areceptor agonist (8-OH-DPAT) on external urethral sphincter activity in a rat model of pudendal nerve injury
Authors: Chen Shih-Ching , Cheng Chen-Li , Fan Wen-Jia , Chen Jia-Jin Jason , Lai Chien-Hung , Peng Chih-Wei
Published: April 2011

Although serotonergic agents have been used to treat patients with stress urinary incontinence, the characteristics of the external urethral sphincter (EUS) activity activated by 5-HT receptors have not been extensively studied. This study examined the effects of the 5-HT1Areceptor agonist, 8-hydroxy-2-(di- n-propylamino)tetralin (8-OH-DPAT), on the EUS-electromyography and resistance of the urethra in a rat model with bilateral pudendal nerve injury (BPNI). Two measurements were utilized to assess the effects of the drug on bladder and urethral functions: the simultaneous recordings of transvesical pressure under isovolumetric conditions [isovolumetric intravesical pressure (IVP)] and urethral perfusion pressure, and the simultaneous recordings of IVP during continuously isotonic transvesical infusion with an open urethra (isotonic IVP) and EUS-electromyography. This study also evaluated the urethral continence using leak point pressure testing. The urethral perfusion pressure and leak point pressure measurements of BPNI rats reveal that 8-OH-DPAT significantly increased urethral resistance during the bladder storage phase, yet decreased resistance during the voiding phase. The entire EUS burst period was significantly prolonged, within which the average silent period increased and the frequency of burst discharges decreased. 8-OH-DPAT also improved the voiding efficiency, as evidenced by the detection of decreases in the contraction amplitude and residual volume, with increases in contraction duration and voided volume. These findings suggest that 8-OH-DPAT not only improved continence function, but also elevated the voiding function in a BPNI rat model.
Growth hormone-stimulated insulin-like growth factor-1 expression in rainbow trout (Oncorhynchus mykiss) hepatocytes is mediated by ERK, PI3K-AKT, and JAK-STAT
Authors: Reindl Katie M. , Kittilson Jeffrey D. , Bergan Heather E. , Sheridan Mark A.
Published: April 2011

Growth hormone (GH) initiates many of its growth-promoting actions by binding to GH receptors (GHR) and stimulating the synthesis and secretion of insulin-like growth factor-1 (IGF-1) from the liver and other sites. In this study, we used hepatocytes isolated from rainbow trout as a model system in which to determine the molecular signaling events of GH in fish. GH directly stimulated the phosphorylation of ERK, protein kinase B (Akt), a downstream target of phosphatidylinositol 3-kinase (PI3K), JAK2, and STAT5 in hepatocytes incubated in vitro. Activation of ERK, Akt, JAK2, and STAT5 was rapid, occurring within 5–10 min, and was concentration dependent. GH-induced ERK activation was completely blocked by the ERK pathway inhibitor, U0126, and the JAK2 inhibitor, 1,2,3,4,5,6-hexabromocyclohexane (Hex), and was partially blocked by the PI3K inhibitor LY294002. GH-stimulated Akt activation was completely blocked by LY294002 and Hex, but was not affected by U0126; whereas, STAT5 activation by GH was blocked only by Hex, and was not affected by either U0126 or LY294002. GH stimulated hepatic expression of IGF-1 mRNA as well as the secretion of IGF-1, effects that were partially or completely blocked by U0126, LY294002, and Hex. These results indicate that GHR linkage to the ERK, PI3K/Akt, or STAT pathways in trout liver cells requires activation of JAK2, and that GH-stimulated IGF-1 synthesis and secretion is mediated through the ERK, PI3K/Akt, and JAK-STAT pathways.
Mitochondrial capacity is affected by glycemic status in young untrained women with type 1 diabetes but is not impaired relative to healthy untrained women
Authors: Item Flurin , Heinzer-Schweizer Susanne , Wyss Michael , Fontana Piero , Lehmann Roger , Henning Anke , Weber Markus , Boesiger Peter , Boutellier Urs , Toigo Marco
Published: April 2011

In this study, we examined whether glycemic status influences aerobic function in women with type 1 diabetes and whether aerobic function is reduced relative to healthy women. To this end, we compared several factors determining aerobic function of 29 young sedentary asymptomatic women (CON) with 9 women of similar age and activity level with type 1 diabetes [DIA, HbA1c range = 6.9–8.2%]. Calf muscle mitochondrial capacity was estimated by 31P-magnetic resonance spectroscopy. Capillarization and muscle fiber oxidative enzyme activity were assessed from vastus lateralis and soleus muscle biopsies. Oxygen uptake and cardiac output were evaluated by ergospirometry and N2O/SF6 rebreathing. Calf muscle mitochondrial capacity was not different between CON and DIA, as indicated by the identical calculated maximal rates of oxidative ATP synthesis [0.0307 (0.0070) vs. 0.0309 (0.0058) s−1, P = 0.930]. Notably, HbA1c was negatively correlated with mitochondrial capacity in DIA ( R2 = 0.475, P = 0.040). Although HbA1c was negatively correlated with cardiac output ( R2 = 0.742, P = 0.013) in DIA, there was no difference between CON and DIA in maximal oxygen consumption [2.17 (0.34) vs. 2.21 (0.32) l/min, P = 0.764], cardiac output [12.1 (1.9) vs. 12.3 (1.8) l/min, P = 0.783], and endurance capacity [532 (212) vs. 471 (119) s, P = 0.475]. There was also no difference between the two groups either in the oxidative enzyme activity or capillary-to-fiber ratio. We conclude that mitochondrial capacity depends on HbA1c in untrained women with type 1 diabetes but is not reduced relative to untrained healthy women.
Metyrapone restores the febrile response to Escherichia coli LPS in pregnant rats
Authors: Alexander Brent N. , Fewell James E.
Published: April 2011

Fever, an important component of the host's defense response to immune challenge, is absent or attenuated in rats near the term of pregnancy. The present experiments were carried out to determine the role of endogenous glucocorticoids in mediating the altered core temperature (Tc) response to exogenous pyrogen (i.e., Escherichia coli LPS). For the experiments, metyrapone—a glucocorticoid synthesis inhibitor—was administered to near-term pregnant rats prior to an EC100dose of E. coli LPS. Administration of LPS following vehicle elicited a significant corticosterone response and resulted in a decrease in Tc (i.e., hypothermia). Prior administration of metyrapone, however, which abolished the corticosterone response and altered the pyrogenic/cryogenic cytokine response to LPS, eliminated hypothermia and restored the febrile response. Our results provide evidence that endogenous glucocorticoids play a role in mediating the altered febrile response to immune stimuli observed in rats near the term of pregnancy.