bluuebunny/crossref_metadata_2025 huggingface dataset:
Efficient infrared photodetector based on three-dimensional self-assembled PbSe superlattices
Authors: Qian Lei , Yang Yixing , Han Changfeng , Cheng Yuanyuan , Chen Ling , Zhang Ting , Xue Wei , Bera Debasis , Holloway Paul H.
Published: July 2014

Highly improved detectivity of Infrared photodetector by using three-dimensional self-assembly PbSe superlattices.
Revealing the tunable photoluminescence properties of graphene quantum dots
Authors: Sk Mahasin Alam , Ananthanarayanan Arundithi , Huang Lin , Lim Kok Hwa , Chen Peng
Published: July 2014

Photoluminescence of graphene quantum-dot can be sensitively tuned by size, edge configurations, shape, chemical functionalities, defects, heteroatom-doping and hybridization states.
Amyloid β-peptide-dependent activation of human platelets: essential role for Ca2+ and ADP in aggregation and thrombus formation
Authors: Canobbio Ilaria , Guidetti Gianni F. , Oliviero Barbara , Manganaro Daria , Vara Dina , Torti Mauro , Pula Giordano
Published: July 2014

Alzheimer's disease is associated with the accumulation of Aβ (amyloid β)-peptides in the brain. Besides their cytotoxic effect on neurons, Aβ-peptides are thought to be responsible for the atherothrombotic complications associated with Alzheimer's disease, which are collectively known as cerebrovascular disease. In the present study, we investigated the effect of Aβ-peptides on human platelet signal transduction and function. We discovered that the 25–35 domain of Aβ-peptides induce an increase in platelet intracellular Ca2+ that stimulates α-granule and dense granule secretion and leads to the release of the secondary agonist ADP. Released ADP acts in an autocrine manner as a stimulant for critical signalling pathways leading to the activation of platelets. This includes the activation of the protein kinases Syk, protein kinase C, Akt and mitogen-activated protein kinases. Ca2+-dependent release of ADP is also the main component of the activation of the small GTPase Rap1b and the fibrinogen receptor integrin αIIbβ3, which leads to increased platelet aggregation and increased thrombus formation in human whole blood. Our discoveries complement existing understanding of cerebrovascular dementia and suggest that Aβ-peptides can induce vascular complications of Alzheimer's disease by stimulating platelets in an intracellular Ca2+-dependent manner. Despite a marginal ADP-independent component suggested by low levels of signalling activity in the presence of apyrase or P2Y receptor inhibitors, Ca2+-dependent release of ADP by Aβ-peptides clearly plays a critical role in platelet activation. Targeting ADP signalling may therefore represent an important strategy to manage the cerebrovascular component of Alzheimer's disease.
Using Multiple Measures to Document Change in English Vowels Produced by Japanese, Korean, and Spanish Speakers: The Case for Goodness and Intelligibility
Authors: Franklin Amber D. , Stoel-Gammon Carol
Published: July 2014

Purpose

This study examined the effectiveness of using goodness ratings and intelligibility scores to document changes in vowel production following pronunciation training. The relationship between listener perceptions of goodness and intelligibility was also examined.

Method

Fifteen English language learner speakers (5 Japanese, 5 Korean, and 5 Spanish) participated in 16 sessions of vowel-focused pronunciation training. Pre- and posttraining judgments of 10 English vowels in /hVt/ context were conducted by 25 monolingual English speakers who served as listeners. Listeners judged vowel intelligibility using a 10-alternative forced-choice task and rated goodness using a 5-point Likert scale.

Results

Goodness ratings and intelligibility scores captured improvement in the accuracy of several vowels following training. However, some vowels that received better mean intelligibility scores received poorer mean goodness ratings following training. The relationship between goodness ratings and intelligibility scores revealed that vowels such as /æ/ and /ʌ/ were more dependent on goodness for intelligibility than vowels such as /i/ and /e/, which were highly intelligible even when they received poor goodness ratings.

Conclusion

English vowels differ with respect to the importance of goodness for accurate identification by listeners. As such, clinicians should examine both goodness and intelligibility when measuring change following pronunciation training.
Speech and Resonance Disorders Related to Cleft Palate and Velopharyngeal Dysfunction: A Guide to Evaluation and Treatment
Authors: Kummer Ann W.
Published: July 2014

Children with speech and/or resonance disorders due to structural anomalies present challenges for speech-language pathologists in all settings. The purpose of this article is to provide current, practical information regarding the evaluation and treatment of children with speech/resonance disorders secondary to cleft palate and noncleft causes of velopharyngeal dysfunction. Simple “no-tech” procedures for assessment will be described so that the reader will be able to determine which children will benefit from therapy and which will require surgical intervention. Finally, specific speech therapy techniques will be given for changing placement from the pharynx to the oral cavity, thus eliminating phoneme-specific nasal emission.
A Comprehensive View of Stuttering: Implications for Assessment and Treatment
Authors: Coleman Craig , Scott Yaruss J.
Published: July 2014

Comprehensive assessment and treatment for school-age children who stutter is critical in effectively managing the affective, behavioral, and cognitive components of the disorder. Using a framework established by the World Health Organization's (WHO's) International Classification of Functioning, Disability, and Health (ICF; WHO, 2001), this paper provides specific assessment and treatment goals for working with school-age children who stutter. It is meant to be a practical guide for clinicians working in the school setting.
Leakage‐based distributed minimum‐mean‐square error beamforming for relay‐assisted cloud radio access networks
Authors: Fei Zesong , Xing Chengwen , Li Na , Zhu Dalin , Lei Ming
Published: July 2014

In this study, the authors investigate the linear minimum‐mean‐square‐error beamforming design for relay‐assisted cloud radio access network (C‐RAN). A standard C‐RAN architecture separates baseband processing units and wireless radio units in order to save energy cost. To further enhance network coverage, several relay nodes (RNs) are also deployed. Regrading the per‐antenna power constraints at both of the remote radio heads (RRHs) and the RNs in the author's work the beamforming matrices at the RRHs and RNs are ‘jointly’ optimised for the considered relay assisted C‐RAN. The considered optimisation problem is a non‐convex and multiple variable optimisation problem which is in general very hard to solve. In order to make the design suitable for large scale networks exploiting to the problem structure a novel two stage decomposition algorithms are proposed. Finally, a detailed mean‐square‐error performance comparison is given by the simulations.
Power transformer protection based on decision tree approach
Authors: Ozgonenel Okan , Karagol Serap
Published: July 2014

This study introduces the concept of decision tree (DT) classification, a new approach to power transformer differential protection. The proposed technique is based on processing the differential current. The suggested method detects winding insulation failures and distinguishes them from magnetising inrush and sympathetic inrush conditions with classification accuracies of 100% for simulations and 95% for real‐time studies. The internal faults can be accurately recognised from inrush current conditions in a few sampling cycle after the occurrence of a disturbance. Another advantage of the proposed method is that the fault detection algorithm does not depend on the selection of thresholds. Performance analysis of the DT is achieved by the simulation of different faults and switching conditions on a power transformer in power system computer aided design/electromagnetic transients including DC (PSCAD/EMTDC). Furthermore, the proposed method is also tested in laboratory environment. The accuracy of DT is also compared with support vector machine. Both experimental and simulation results are presented and discussed.
Omnidirectional microstrip patch antenna with reconfigurable pattern and polarisation
Authors: Narbudowicz Adam , Bao Xiulong , Ammann Max James
Published: July 2014

An omnidirectional microstrip patch antenna, capable of reconfiguring both polarisation and radiation pattern is proposed. It operates with two orthogonal ±45° slanted linear polarisations and can produce two dipole‐like radiation patterns, providing 360° coverage in either the horizontal or elevation plane. With appropriate steering, this enables a single antenna to provide full spherical coverage for any polarisation. The reconfiguration is realised by phase shifting, thus does not require switching elements, such as microelectromechanical system or pin diodes embedded into antenna. The basic principles of operation are discussed and validated by numerical and measured data.
Self‐assembled multilayer wrinkles on coated polymer surface
Authors: Wang Bin , Ren Jie , Ye Yong‐Hong
Published: July 2014

When coating different dielectrics on polymer surfaces, the surface morphology could be changed to wrinkles or cracks. The wrinkles or cracks are self‐formed during the process of heating and cooling. The presented experimental results show that the wrinkles can be self‐aligned between two nearest patterns. The direction of aligned wrinkles can be tuned to parallel, perpendicular and required degrees according to the different array‐based patterns. The number of wrinkles can also be controlled by changing the size of the patterns. In a limited range, a larger size pit has more wrinkles.
Ultrastructure of symbiotic germination of the orchid Dendrobium officinale with its mycobiont, Sebacina sp.
Authors: Chen J. , Wang H. , Liu S. S. , Li Y. Y. , Guo S. X.
Published: July 2014

Dendrobium officinale is an endangered epiphytic orchidaceous medicinal plant. Similar to other orchid plants, the seed germination of D. officinale under natural conditions depends nutritionally upon mycorrhizal fungi. The compatible fungi have been isolated from D. officinale protocorms using in situ seed baiting technique in our previous studies. However, the interaction between seed germination of D. officinale and its mycobiont is still unclear. In the present study, we investigated the morphological changes of seed and fungus during the symbiotic germination using a light microscope and transmission electron microscope. Seeds of D. officinale have no conspicuous suspensor cells. The fungus enters into the embryo cell through the posterior end of the embryo and colonises the cortical cell in the first stage of germination (Stage 1). Then, the hyphae form pelotons with the protocorm development (Stages 1–3). After protocorm formation, the reinvaded fungal hyphae conspicuously decrease. Invaded hyphae lose bioactivity, form clumps and start degeneration at Stage 4 or 5 (seedling development). When penetrating the neighbouring cortical cell, the fungal hyphae constrict to collar shape at the contacted site and follow by swelling in the apex. Our study suggested that fungi trigger protocorm development and concomitant reserve utilisation during the symbiotic germination.
Planktonic duration in fourteen species of intertidal rocky fishes from the south-eastern Pacific Ocean
Authors: Mansur Lidia , Plaza Guido , Landaeta Mauricio F. , Ojeda F. Patricio
Published: July 2014

The planktonic duration (PD) was determined in fourteen intertidal rocky fishes from the south-eastern Pacific Ocean by counting the otolith micro-increments from hatch check to a transition mark (TM). TMs were validated by comparing the PDs estimated from post-settlers with the total increment counts from otoliths of more recent (new) settlers. In 11 species (79%), the most common TM corresponded to a notable decrease in increment width after settlement. The PDs ranged from 45 days in the kyphosid Girella laevifrons to 135 days in the labrisomid Auchenionchus variolosus, and eight species (57%) had mean PDs of longer than three months. The mean observed size-at-settlement (SASM) values ranged from 17.5 ± 7.2 mm TL in Gobiesox marmoratus (Gobiesocidae) to 40 ± 5.5 mm TL in Calliclinus geniguttatus (Labrisomidae) and showed low variability within species of the same family. PDs were markedly longer in intertidal rocky fishes than in other littoral and reef fishes in tropical and temperate waters. A lengthy and variable duration of the pre-settlement phase, along with a relatively consistent size-at-competence within closely related species, are suggested as mechanisms through which these fishes may increase their probability to settle in the spatially restricted habitat of exposed rocky pools.
Combining in-trawl video with observer coverage improves understanding of protected and vulnerable species by-catch in trawl fisheries
Authors: Jaiteh Vanessa F. , Allen Simon J. , Meeuwig Jessica J. , Loneragan Neil R.
Published: July 2014

Assessments of incidental wildlife mortality resulting from fishing rarely account for unobserved by-catch. We assessed by-catch of protected and vulnerable wildlife species in an Australian trawl fishery by comparing in-trawl video footage with data collected by an on-board observer. Data were obtained from 44 commercial trawls with two different by-catch reduction devices (BRDs). Eighty-six individuals from six major taxa (dolphins, sharks, rays, sea snakes, turtles and sygnathids) were documented from video analysis, including the endangered scalloped hammerhead shark (Sphyrna lewini) and the critically endangered green sawfish (Pristis zijsron). On the basis of the 2008–2009 fishing effort of 4149 trawls and scaling from these results, we estimated the annual catch of protected and vulnerable species (± 1 s.e.) at 8109 ± 910 individuals. Only 34% of by-catch was expelled through the BRDs. Independent observer data for the 44 trawls showed that 77% of the landed by-catch from these taxa were dead when discarded. The results indicate that unaccounted by-catch in trawl fisheries can be substantial, and that current methods of recording by-catch on-board vessels are likely to underestimate total fishing mortality. We recommend gear modifications and their validation through dedicated observer coverage, combined with in-trawl video camera deployments to improve current approaches to by-catch mitigation.
Pyrosequencing analysis of microbiota reveals that lactic acid bacteria are dominant in Korean flat fish fermented food,gajami-sikhae
Authors: Kim Hyo Jin , Kim Min-Jeong , Turner Timothy Lee , Kim Bong-Soo , Song Kyung-Mo , Yi Sung Hun , Lee Myung-Ki
Published: July 2014

The gajami-sikhae, traditional Korean cuisine fermented with flat fish, samples were collected from eight different manufacturers (GS1–GS8). We employed pyrosequencing method to analyze the bacterial communities of the gajami-sikhae samples. Family- and genus-level analyses indicated that the bacterial community compositions of GS3 and GS6 were distinct from those of the rest. The species-level structures of bacterial communities of the gajami-sikhae samples except for GS3 and GS6 featured Lactobacillus sakei as the most abundant species. Leuconostoc mesenteroides was revealed as the most dominant species among the bacterial community of GS6 and the bacterial community of GS3 was composed of various lactic acid bacteria. We employed a culture-based method to isolate beneficial strains from the gajami-sikhae samples. However, most of the 47 selected colonies were identified as Bacillus subtilis and Bacillus amyloliquefaciens. This study indicated that gajami-sikhae was mainly composed of many beneficial lactic acid bacteria.
On Jordan-Hölder series of some locally analytic representations
Authors: Orlik Sascha , Strauch Matthias
Published: July 2014

Let

G
G

be a split reductive

p
p

-adic group. This paper is about the Jordan-Hölder series of locally analytic

G
G

-representations which are induced from locally algebraic representations of a parabolic subgroup

P
⊂
G

P \subset G

. We construct for every representation

M
M

of

Lie

(
G
)

\textrm {Lie}(G)

in the BGG-category

O

{\mathcal O}

, which is equipped with an algebraic

P
P

-action, and for every smooth

P
P

-representation

V
V

, a locally analytic representation

F

P
G

(
M
,
V
)

{\mathcal F}^G_P(M,V)

of

G
G

. This gives rise to a bi-functor to the category of locally analytic representations. We prove that it is exact and give a criterion for the topological irreducibility of

F

P
G

(
M
,
V
)

{\mathcal F}^G_P(M,V)

in terms of

M
M

and

V
V

.
Conservation relations for local theta correspondence
Authors: Sun Binyong , Zhu Chen-Bo
Published: July 2014

We prove Kudla-Rallis conjecture on first occurrences of local theta correspondence, for all irreducible dual pairs of type I and all local fields of characteristic zero.
Nutrition: A Very Short Introduction
Authors: Bender David
Published: July 2014

Nutrition is a topic of wide interest and importance. In spite of a growing understanding of the underlying biochemistry, and health campaigns such as ‘five-a-day’, increasing obesity and reported food allergies and eating disorders, as well as the widely advertised ‘supposed’ benefits of food supplements mean that a clear explanation of the basic principles of a healthy diet are vital. Nutrition: A Very Short Introduction explains the basic elements of food, the balance between energy intake and exercise, the problems of over- and under-nutrition, and raises the question of the safety of nutritional supplements.
The main sequence of star-forming galaxies at z ∼ 0.6: reinstating major mergers
Authors: Puech M. , Hammer F. , Rodrigues M. , Fouquet S. , Flores H. , Disseau K.
Published: July 2014

The relation between the star formation rate (SFR) and the stellar mass of star-forming galaxies has been used to argue that major mergers cannot be the main driver of star formation. Here, we re-examine these arguments using the representative IMAGES-CDFS sample of star-forming galaxies at z = 0.4–0.75, taking advantage of their previously established classification into pre-fusion, fusion, and relaxing galaxy mergers. Contrary to previous claims, we show there is no tension between the main-sequence scatter and the average duration of the fusion SFR peak. We confirm previous estimates of the fraction of SFR due to morphologically selected galaxies (∼23 per cent) or the SFR enhancement due to major merger during the fusion phase (∼10 per cent). However, galaxy mergers are not instantaneous processes, which implies that the total fraction of the SFR associated with galaxies undergoing major mergers must account for the three merger phases. When doing so, galaxies involved in major mergers are found to represent 53–88 per cent of the total SFR at z ∼ 0.6. The fraction of luminous infrared galaxies (LIRGs) in the fusion phase is found to be in agreement with the observed morphological fraction of LIRGs without discs and with the observed and expected major merger rates at z ≤ 1.5.
Comparison of Resistance to Asiatic Citrus Canker Among Different Genotypes of Citrus in a Long-Term Canker-Resistance Field Screening Experiment in Brazil
Authors: de Carvalho Sérgio Alves , de Carvalho Nunes William Mário , Belasque José , Machado Marcos Antonio , Croce-Filho José , Bock Clive H. , Abdo Zaid
Published: July 2014

Asiatic citrus canker (ACC) is caused by Xanthomonas citri subsp. citri. The disease results in yield loss and renders fruit unfit for the fresh market. A 6-year study in Paraná State, Brazil, was conducted to compare the susceptibility of 186 genotypes of citrus representing sweet orange (Citrus sinensis), mandarin (C. reticulata), Mediterranean mandarin (C. deliciosa), Clementine mandarin (C. clementina), Satsuma mandarin (C. unshiu), sour orange (C. aurantium), lemon (C. limon), sweet lime (C. aurantifolia), grapefruit (C. paradisi), and four hybrids (C. reticulata × Citrus sp., C. reticulata × C. paradisi, C. reticulata × C. sinensis, and C. unshiu × C. sinensis). Sweet orange (C. sinensis) was represented by the most genotypes (n = 141). The number of lesions per leaf was assessed 18 times from 2005 to 2010 (up to 4 times per year). The data were analyzed using mixed-model analysis of fixed and random effects, which showed a total of six resistance-susceptibility groupings of species and hybrids. Based on species, the most resistant genotypes, on average, included Satsuma and lemon (mean lesions per leaf = 4.32 and 4.26, respectively), and the most susceptible genotypes were grapefruit and sweet lime, with 14.84 and 10.96 lesions per leaf, respectively. Genotypes of mandarin, sour orange, Mediterranean mandarin, and sweet orange had intermediate severity (5.48 to 9.56 lesions per leaf). The hybrids also showed a range of ACC severity but all were in the more resistant groupings (5.26 to 7.35 lesions per leaf). No genotype was immune to ACC. The most resistant genotype was ‘Muscia’ (C. reticulata) and the most susceptible was ‘Valencia Frost’ (C. sinensis) (1.86 and 14.78 lesions per leaf, respectively). Approximately one-sixth of the genotypes showed a negative relationship of mean lesions per leaf with time, suggesting increasing resistance as they aged, due to a reduction in either new flush or plant size and structure. These results of the relative susceptibility of different citrus genotypes can be used in future research and to assist in varietal selection or for breeding purposes both within Brazil and other regions where ACC is an issue.
Microdochium tabacinum, Confirmed as a Pathogen of Alfalfa in Gansu Province, China
Authors: Wen Zhaohui , Duan Tingyu , Christensen Michael J. , Nan Zhibiao
Published: July 2014

A crown and root rot complex was detected in the alfalfa (Medicago sativa ‘Longdong’) fields of Huanxian County. The symptoms of the diseased plants were characterized, and 11 fungal species were obtained from the roots. These fungi included isolates that resembled the genus Microdochium. An isolate of this type, designated MP313, was proven to infect alfalfa, fulfilling Koch's postulates. Isolate MP313 was examined by microscopy and the morphological characteristics indicated that it was similar to members of the genus Microdochium. Sequence analyses of the 28S large subunit as well as the internal transcribed spacer (ITS) region of the ribosomal DNA (rDNA) of MP313 revealed 98 to 100% similarity to the corresponding regions of M. tabacinum. A polymerase chain reaction assay based on the ITS region of the rDNA was developed to amplify a 304-bp fragment from DNA concentrations as low as 20 fg/μl, which was sensitive enough to detect isolate MP313 in diseased root samples. Taken together, these results confirmed that M. tabacinum was one of a complex of fungi associated with crown and root rot in the alfalfa samples collected in Gansu Province. This is the first report of M. tabacinum being a pathogen of alfalfa in China.
Streptomyces araujoniae Produces a Multiantibiotic Complex with Ionophoric Properties to Control Botrytis cinerea
Authors: Silva Leonardo José , Crevelin Eduardo José , Souza Wallace Rafael , Moraes Luiz Alberto Beraldo , Melo Itamar Soares , Zucchi Tiago Domingues
Published: July 2014

A recently described actinomycete species (Streptomyces araujoniae ASBV-1T) is effective against many phytopathogenic fungi. In this study, we evaluated the capacity of this species to inhibit Botrytis cinerea development in strawberry pseudofruit, and we identified the chemical structures of its bioactive compounds. An ethyl acetate crude extract (0.1 mg ml−1) of ASBV-1T fermentation broth completely inhibited fungus growth in strawberry pseudofruit under storage conditions. The crude extract was fractionated by preparative high-performance liquid chromatography; the active fraction was further evaluated by tandem mass spectrometry. ASBV-1T produced a multiantibiotic complex with ionophoric properties. This complex contained members of the macrotetralides class (including monactin, dinactin, trinactin, and tetranactin) and the cyclodepsipeptide valinomycin, all of which were active against B. cinerea. Furthermore, the addition of 2 mM MgSO4 and 1 mM ZnSO4 enhanced macrotetralide and valinomycin production, respectively, in the culture broth. These compounds are considered to be the main active molecules that S. araujoniae produces to control B. cinerea. Their low to moderate toxicity to humans and the environment justifies the application of ASBV-1T in biological control programs that aim to mitigate the damage caused by this phytopathogen.
Modeling Individual Recovery after Peripheral Nerve Injury in Rats and the Effects of Parturition
Authors: Aschenbrenner Carol A. , Houle Timothy T. , Gutierrez Silvia , Eisenach James C.
Published: July 2014

Background:

Recovery from pain after surgery exhibits large interindividual variability, with very slow recovery equated to chronic pain. Surgical injury in the postpartum period modestly increases initial recovery after major nerve injury. In this study, the authors use a nerve injury that recovers over 2 to 3 months and apply growth curve modeling to further understand the effect of the postpartum period on speed of recovery.

Methods:

Withdrawal threshold to mechanical stimulus on the hind paw was determined in 41 Sprague–Dawley rats before and for 10 weeks after partial spinal nerve ligation. Age-matched male and female rats and postpartum females with pups or those separated from pups at delivery were studied. Growth curve analyses were applied to model recovery after surgery despite varying timing of measurements across groups and missing data, and these results were compared with those of two-way repeated-measures ANOVA.

Results:

The recovery time course was similar between males and females. In contrast, recovery was hastened in the postpartum groups, with nonoverlapping 95% CIs of modeled trajectories between days 6 and 66 after surgery. CIs were more precise at most time periods with growth curve analysis compared with ANOVA.

Conclusions:

The authors describe a method of analysis to quantify recovery from hypersensitivity after surgery in rats with several distinct advantages over traditionally used methods. Study results do not support a sex difference in trajectory of recovery but confirm and extend previous observations that injury at the time of obstetric delivery is associated with an abnormally rapid recovery.
Resistance Patterns of Typhoid Fever in Children: A Longitudinal Community-Based Study
Authors: Vala Snehal , Shah Urvesh , Ahmad Syed Amir , Scolnik Dennis , Glatstein Miguel
Published: July 2014

Salmonella typhi and S. paratyphi are important causes of bacteremia in children, especially those from the developing world. There is a lack of standardized treatment protocols for such patients in the literature, and there are also reports of therapeutic failure related to resistance to commonly used antibiotics. We analyzed the epidemiological, clinical, and antimicrobiological sensitivity patterns of disease in patients diagnosed with blood culture–positive typhoid fever over a 6-month period in a tertiary-care pediatric hospital in western India. Data were retrospectively analyzed for all patients with Salmonella isolates on blood culture between January 1 and June 30, 2011 at the Synergy Neonatal and Pediatric Hospital. Susceptibility of isolates to antimicrobials and minimum inhibitory concentrations were determined. Demographic data, symptoms and signs, basic laboratory results, treatment courses, and clinical outcomes were collected from clinical charts. All of the 61 isolates of S. typhi were sensitive to cefepime (fourth-generation cephalosporin), 96% to third-generation cephalosporins, and 95% to quinolones. There was intermediate sensitivity to ampicillin (92%) and chloramphenicol (80%). Notably, azithromycin resistance was observed in 63% of isolates. All patients ultimately made full recoveries. There is an urgent need for large scale, community-based clinical trials to evaluate the effectiveness of different antibiotics in enteric fever. Our antimicrobial susceptibility data suggest that quinolones and third-generation cephalosporins should be used as first-line antimicrobials in enteric fever. Although fourth-generation cephalosporins are useful, we feel their use should be restricted to complicated or resistant cases.
Ectomycorrhizal fungi and past high CO2atmospheres enhance mineral weathering through increased below-ground carbon-energy fluxes
Authors: Quirk Joe , Andrews Megan Y. , Leake Jonathan R. , Banwart Steve A. , Beerling David J.
Published: July 2014

Field studies indicate an intensification of mineral weathering with advancement from arbuscular mycorrhizal (AM) to later-evolving ectomycorrhizal (EM) fungal partners of gymnosperm and angiosperm trees. We test the hypothesis that this intensification is driven by increasing photosynthate carbon allocation to mycorrhizal mycelial networks using14CO2-tracer experiments with representative tree–fungus mycorrhizal partnerships. Trees were grown in either a simulated past CO2atmosphere (1500 ppm)—under which EM fungi evolved—or near-current CO2(450 ppm). We report a direct linkage between photosynthate-energy fluxes from trees to EM and AM mycorrhizal mycelium and rates of calcium silicate weathering. Calcium dissolution rates halved for both AM and EM trees as CO2fell from 1500 to 450 ppm, but silicate weathering by AM trees at high CO2approached rates for EM trees at near-current CO2. Our findings provide mechanistic insights into the involvement of EM-associating forest trees in strengthening biological feedbacks on the geochemical carbon cycle that regulate atmospheric CO2over millions of years.
The kangaroo's tail propels and powers pentapedal locomotion
Authors: O'Connor Shawn M. , Dawson Terence J. , Kram Rodger , Donelan J. Maxwell
Published: July 2014

When moving slowly, kangaroos plant their tail on the ground in sequence with their front and hind legs. To determine the tail's role in this ‘pentapedal’ gait, we measured the forces the tail exerts on the ground and calculated the mechanical power it generates. We found that the tail is responsible for as much propulsive force as the front and hind legs combined. It also generates almost exclusively positive mechanical power, performing as much mass-specific mechanical work as does a human leg during walking at the same speed. Kangaroos use their muscular tail to support, propel and power their pentapedal gait just like a leg.
The scaling of human interactions with city size
Authors: Schläpfer Markus , Bettencourt Luís M. A. , Grauwin Sébastian , Raschke Mathias , Claxton Rob , Smoreda Zbigniew , West Geoffrey B. , Ratti Carlo
Published: July 2014

The size of cities is known to play a fundamental role in social and economic life. Yet, its relation to the structure of the underlying network of human interactions has not been investigated empirically in detail. In this paper, we map society-wide communication networks to the urban areas of two European countries. We show that both the total number of contacts and the total communication activity grow superlinearly with city population size, according to well-defined scaling relations and resulting from a multiplicative increase that affects most citizens. Perhaps surprisingly, however, the probability that an individual's contacts are also connected with each other remains largely unaffected. These empirical results predict a systematic and scale-invariant acceleration of interaction-based spreading phenomena as cities get bigger, which is numerically confirmed by applying epidemiological models to the studied networks. Our findings should provide a microscopic basis towards understanding the superlinear increase of different socioeconomic quantities with city size, that applies to almost all urban systems and includes, for instance, the creation of new inventions or the prevalence of certain contagious diseases.
The Matthew effect in empirical data
Authors: Perc Matjaž
Published: July 2014

The Matthew effect describes the phenomenon that in societies, the rich tend to get richer and the potent even more powerful. It is closely related to the concept of preferential attachment in network science, where the more connected nodes are destined to acquire many more links in the future than the auxiliary nodes. Cumulative advantage and success-breads-success also both describe the fact that advantage tends to beget further advantage. The concept is behind the many power laws and scaling behaviour in empirical data, and it is at the heart of self-organization across social and natural sciences. Here, we review the methodology for measuring preferential attachment in empirical data, as well as the observations of the Matthew effect in patterns of scientific collaboration, socio-technical and biological networks, the propagation of citations, the emergence of scientific progress and impact, career longevity, the evolution of common English words and phrases, as well as in education and brain development. We also discuss whether the Matthew effect is due to chance or optimization, for example related to homophily in social systems or efficacy in technological systems, and we outline possible directions for future research.
Design and control of compliant tensegrity robots through simulation and hardware validation
Authors: Caluwaerts Ken , Despraz Jérémie , Işçen Atıl , Sabelhaus Andrew P. , Bruce Jonathan , Schrauwen Benjamin , SunSpiral Vytas
Published: July 2014

To better understand the role of tensegrity structures in biological systems and their application to robotics, the Dynamic Tensegrity Robotics Lab at NASA Ames Research Center, Moffett Field, CA, USA, has developed and validated two software environments for the analysis, simulation and design of tensegrity robots. These tools, along with new control methodologies and the modular hardware components developed to validate them, are presented as a system for the design of actuated tensegrity structures. As evidenced from their appearance in many biological systems, tensegrity (‘tensile–integrity’) structures have unique physical properties that make them ideal for interaction with uncertain environments. Yet, these characteristics make design and control of bioinspired tensegrity robots extremely challenging. This work presents the progress our tools have made in tackling the design and control challenges of spherical tensegrity structures. We focus on this shape since it lends itself to rolling locomotion. The results of our analyses include multiple novel control approaches for mobility and terrain interaction of spherical tensegrity structures that have been tested in simulation. A hardware prototype of a spherical six-bar tensegrity, the Reservoir Compliant Tensegrity Robot, is used to empirically validate the accuracy of simulation.
Factored solution of nonlinear equation systems
Authors: Gómez-Expósito Antonio
Published: July 2014

This article generalizes a recently introduced procedure to solve nonlinear systems of equations, radically departing from the conventional Newton–Raphson scheme. The original nonlinear system is first unfolded into three simpler components: (i) an underdetermined linear system, (ii) a one-to-one nonlinear mapping with explicit inverse, and (iii) an overdetermined linear system. Then, instead of solving such an augmented system at once, a two-step procedure is proposed in which two equation systems are solved at each iteration, one of them involving the same symmetric matrix throughout the solution process. The resulting factored algorithm converges faster than Newton's method and, if carefully implemented, can be computationally competitive for large-scale systems. It can also be advantageous for dealing with infeasible cases.
On bifurcations in lifts of regular uniform coupled cell networks
Authors: Moreira Célia Sofia
Published: July 2014

A
lift
of a given network is a network that admits the first network as quotient. Assuming that a bifurcation occurs for a coupled cell system consistent with the structure of a regular network (in which all cells have the same type and receive the same number of inputs and all arrows have the same type), it is well known that some lifts exhibit new bifurcating branches of solutions. In this work, we approach this problem restricting attention to uniform networks, that is, networks that have no loops and no multiple arrows. We show that, from the bifurcation point of view, rings and their lifts are special networks. We also prove that generically there are lifts that just exhibit the bifurcating branches determined by the quotient network and, moreover, we identify all generic situations where lifts exist that may exhibit bifurcating branches that do not appear in the quotient itself.
How much gene flow is needed to avoid inbreeding depression in wild tiger populations?
Authors: Kenney John , Allendorf Fred W. , McDougal Charles , Smith James L. D.
Published: July 2014

The number and size of tiger populations continue to decline owing to habitat loss, habitat fragmentation and poaching of tigers and their prey. As a result, tiger populations have become small and highly structured. Current populations have been isolated since the early 1970s or for approximately seven generations. The objective of this study is to explore how inbreeding may be affecting the persistence of remaining tiger populations and how dispersal, either natural or artificial, may reduce the potentially detrimental effect of inbreeding depression. We developed a tiger simulation model and used published levels of genetic load in mammals to simulate inbreeding depression. Following a 50 year period of population isolation, we introduced one to four dispersing male tigers per generation to explore how gene flow from nearby populations may reduce the negative impact of inbreeding depression. For the smallest populations, even four dispersing male tigers per generation did not increase population viability, and the likelihood of extinction is more than 90% within 30 years. Unless habitat connectivity is restored or animals are artificially introduced in the next 70 years, medium size wild populations are also likely to go extinct, with only four to five of the largest wild tiger populations likely to remain extant in this same period without intervention. To reduce the risk of local extinction, habitat connectivity must be pursued concurrently with efforts to increase population size (e.g. enhance habitat quality, increase habitat availability). It is critical that infrastructure development, dam construction and other similar projects are planned appropriately so that they do not erode the extent or quality of habitat for these populations so that they can truly serve as future source populations.
Using social parasitism to test reproductive skew models in a primitively eusocial wasp
Authors: Green Jonathan P. , Cant Michael A. , Field Jeremy
Published: July 2014

Remarkable variation exists in the distribution of reproduction (skew) among members of cooperatively breeding groups, both within and between species. Reproductive skew theory has provided an important framework for understanding this variation. In the primitively eusocial Hymenoptera, two models have been routinely tested: concessions models, which assume complete control of reproduction by a dominant individual, and tug-of-war models, which assume on-going competition among group members over reproduction. Current data provide little support for either model, but uncertainty about the ability of individuals to detect genetic relatedness and difficulties in identifying traits conferring competitive ability mean that the relative importance of concessions versus tug-of-war remains unresolved. Here, we suggest that the use of social parasitism to generate meaningful variation in key social variables represents a valuable opportunity to explore the mechanisms underpinning reproductive skew within the social Hymenoptera. We present a direct test of concessions and tug-of-war models in the paper waspPolistes dominulusby exploiting pronounced changes in relatedness and power structures that occur following replacement of the dominant by a congeneric social parasite. Comparisons of skew in parasitized and unparasitized colonies are consistent with a tug-of-war over reproduction withinP. dominulusgroups, but provide no evidence for reproductive concessions.
Prevalence and genotypes of Campylobacter jejuni from urban environmental sources in comparison with clinical isolates from children
Authors: Ramonaite Sigita , Kudirkiene Egle , Tamuleviciene Egle , Leviniene Giedra , Malakauskas Alvydas , Gölz Greta , Alter Thomas , Malakauskas Mindaugas
Published: July 2014

This study aimed to investigate the prevalence of Campylobacter jejuni in potential contamination sources that are not regularly monitored such as free-living urban pigeons and crows, dogs, cats and urban environmental water and to assess the possible impact on the epidemiology of campylobacteriosis in children using multilocus sequence typing (MLST). Campylobacter spp. were detected in 36.2 % of faecal samples of free-living urban birds and in 40.4 % of environmental water samples. A low prevalence of Campylobacter spp. was detected in dogs and cats, with 7.9 and 9.1 %, respectively. Further identification of isolates revealed that environmental water and pet samples were mostly contaminated by other Campylobacter spp. than C. jejuni, whereas C. jejuni was the most prevalent species in faecal samples of free-living birds (35.4 %). This species was the dominant cause of campylobacteriosis in children (91.5 %). In addition, the diversity of C. jejuni MLST types in free-living birds and children was investigated. Clonal complex (CC) 179 was predominant among free-living urban birds; however, only two isolates from children were assigned to this CC. One dog and one child isolate were assigned to the same clonal complex (CC48) and sequence type (ST) 918. The dominant two clonal complexes among the child clinical isolates (CC353 and CC21) were not detected among C. jejuni strains isolated from environmental sources examined in this study. As only two CCs were shared by environmental and child C. jejuni isolates and a high number of novel alleles and STs were found in C. jejuni isolated from free-living urban birds and environmental water, there is probably only a limited link between urban environmental sources and campylobacteriosis in children, particularly in rather cold climatic conditions.
Genetic and mutational characterization of the small alarmone synthetase gene relV of Vibrio cholerae
Authors: Dasgupta Shreya , Basu Pallabi , Pal Ritesh Ranjan , Bag Satyabrata , Bhadra Rupak K.
Published: July 2014

InVibrio cholerae, the causative agent of cholera, products of three genes,relA,spoTandrelV, govern nutritional stress related stringent response (SR). SR in bacteria is critically regulated by two intracellular small molecules, guanosine 3′-diphosphate 5′-triphosphate (pppGpp) and guanosine 3′,5′-bis(diphosphate) (ppGpp), collectively called (p)ppGpp or alarmone. Evolution ofrelVis unique inV. choleraebecause other Gram-negative bacteria carry onlyrelAandspoTgenes. Recent reports suggest that RelV is needed for pathogenesis. RelV carries a single (p)ppGpp synthetase or RelA-SpoT domain (SYNTH/RSD) and belongs to the small alarmone synthetase (SAS) family of proteins. Here, we report extensive functional characterizations of therelVgene by constructing several deletion and site-directed mutants followed by their controlled expression in (p)ppGpp0cells ofEscherichia coliorV. cholerae. Substitution analysis indicated that the amino acid residues K107, D129, R132, L150 and E188 of the RSD region of RelV are essential for its activity. While K107, D129 and E188 are highly conserved in RelA and SAS proteins, L150 appears to be conserved in the latter group of enzymes, and the R132 residue was found to be unique in RelV. Extensive progressive deletion analysis indicated that the amino acid residues at positions 59 and 248 of the RelV protein are the functional N- and C-terminal boundaries, respectively. Since the minimal functional length of RelV was found to be 189 aa, which includes the 94 aa long RSD region, it seems that the flanking residues of the RSD are also important for maintaining the (p)ppGpp synthetase activity.
H-NS regulates the Vibrio parahaemolyticus type VI secretion system 1
Authors: Salomon Dor , Klimko John A. , Orth Kim
Published: July 2014

The marine bacterium Vibrio parahaemolyticus, a major cause of food-borne gastroenteritis, employs a type VI secretion system 1 (T6SS1), a recently discovered protein secretion system, to combat competing bacteria. Environmental signals such as temperature, salinity, cell density and surface sensing, as well as the quorum-sensing master regulator OpaR, were previously reported to regulate T6SS1 activity and expression. In this work, we set out to identify additional transcription regulators that control the tightly regulated T6SS1 activity. To this end, we determined the effect of deletions in several known virulence regulators and in two regulators encoded within the T6SS1 gene cluster on expression and secretion of the core T6SS component Hcp1 and on T6SS1-mediated anti-bacterial activity. We report that VP1391 and VP1407, transcriptional regulators encoded within the T6SS1 gene cluster, are essential for T6SS1 activity. Moreover, we found that H-NS, a bacterial histone-like nucleoid structuring protein, which mediates transcription silencing of horizontally acquired genes, serves as a repressor of T6SS1. We also show that activation of surface sensing and high salt conditions alleviate the H-NS-mediated repression. Our results shed light on the complex network of environmental signals and transcription regulators that govern the tight regulation over T6SS1 activity.
Lymantria dispar iflavirus 1 (LdIV1), a new model to study iflaviral persistence in lepidopterans
Authors: Carrillo-Tripp Jimena , Krueger Elizabeth N. , Harrison Robert L. , Toth Amy L. , Miller W. Allen , Bonning Bryony C.
Published: July 2014

The cell line IPLB-LD-652Y, derived from the gypsy moth (Lymantria dispar L.), is routinely used to study interactions between viruses and insect hosts. Here we report the full genome sequence and biological characteristics of a small RNA virus, designated Lymantria dispar iflavirus 1 (LdIV1), that was discovered to persistently infect IPLB-LD-652Y. LdIV1 belongs to the genus Iflavirus. LdIV1 formed icosahedral particles of approx. 30 nm in diameter and contained a 10 044 nt polyadenylated, positive-sense RNA genome encoding a predicted polyprotein of 2980 aa. LdIV1 was induced by a viral suppressor of RNA silencing, suggesting that acute infection is restricted by RNA interference (RNAi). We detected LdIV1 in all tested tissues of gypsy-moth larvae and adults, but the virus was absent from other L. dispar-derived cell lines. We confirmed LdIV1 infectivity in two of these cell lines (IPLB-LD-652 and IPLB-LdFB). Our results provide a novel system to explore persistent infections in lepidopterans and a new model for the study of iflaviruses, a rapidly expanding group of viruses, many of which covertly infect their hosts.