bluuebunny/crossref_metadata_2025 huggingface dataset:
Transverse instability of ion acoustic solitons in a magnetized plasma including -nonextensive electrons and positrons
Authors: Akhtar N. , El-Taibany W. F. , Mahmood S. , Behery E. E. , Khan S. A. , Ali S. , Hussain S.
Published: September 2015

A nonlinear Zakharov–Kuznetsov (ZK) equation for ion acoustic solitary waves (IASWs) is derived using the reductive perturbation method (RPM) for magnetized plasmas in which the inertialess electrons and positrons are nonextensively $q$-distributed while ions are assumed to be warm and inertial. It is found that both compressive as well as rarefactive solitons coexist in the present model for different regions of non-extensive electron and positron parameters, $q_{e}$ and $q_{p}$. The magnetic field has no effect on the amplitude of the IASW, whereas the obliqueness angle of the wave propagation, the ion-to-electron temperature ratio ${\it\sigma}$ and positron-to-ion density concentration ratio $p$ affect both the amplitude and the width of the solitary wave structures. The transverse instability analysis illustrates that the one soliton solution has a constant growth rate, and it suffers from instability in the transverse direction. The relevance of the present study to astrophysical space plasmas is also discussed.
Characterization of Leucetta prolifera, a calcarean cyanosponge from south-western Australia, and its symbionts
Authors: Fromont Jane , Huggett Megan J. , Lengger Sabine K. , Grice Kliti , Schönberg Christine H.L.
Published: September 2015

The biology and ecology of calcarean sponges are not as well understood as they are for demosponges. Here, in order to gain new insights, particularly about symbiotic relationships, the calcarean sponge Leucetta prolifera was sampled from south-western Australia and examined for its assumed photosymbionts. Pulse amplitude modulated fluorometry and extraction of photopigments established that the sponge was photosynthetic. Molecular analysis of the bacterial symbionts via sequencing of the V1–V3 region of the 16S rDNA gene confirmed that between 5 and 22% of all sequences belonged to the phylum Cyanobacteria, depending on the individual sample, with the most dominant strain aligning with Hormoscilla spongeliae, a widely distributed sponge symbiont. Analysis of fatty acids suggested that the sponge obtains nutrition through photosynthates from its symbionts. The relationship is assumed to be mutualistic, with the sponge receiving dietary support and the cyanobacteria sheltering in the sponge tissues. We list all Calcarea presently known to harbour photosymbionts.
Mercury, selenium and fish oils in marine food webs and implications for human health
Authors: Gribble Matthew O. , Karimi Roxanne , Feingold Beth J. , Nyland Jennifer F. , O'Hara Todd M. , Gladyshev Michail I. , Chen Celia Y.
Published: September 2015

Humans who eat fish are exposed to mixtures of healthful nutrients and harmful contaminants that are influenced by environmental and ecological factors. Marine fisheries are composed of a multitude of species with varying life histories, and harvested in oceans, coastal waters and estuaries where environmental and ecological conditions determine fish exposure to both nutrients and contaminants. Many of these nutrients and contaminants are thought to influence similar health outcomes (i.e., neurological, cardiovascular, immunological systems). Therefore, our understanding of the risks and benefits of consuming seafood require balanced assessments of contaminants and nutrients found in fish and shellfish. In this paper, we review some of the reported benefits of fish consumption with a focus on the potential hazards of mercury exposure, and compare the environmental variability of fish oils, selenium and mercury in fish. A major scientific gap identified is that fish tissue concentrations are rarely measured for both contaminants and nutrients across a range of species and geographic regions. Interpreting the implications of seafood for human health will require a better understanding of these multiple exposures, particularly as environmental conditions in the oceans change.
Trophic ecology of the blue shark (Prionace glauca) based on stable isotopes (δ13C and δ15N) and stomach content
Authors: Hernández-Aguilar Sandra Berenice , Escobar-Sánchez Ofelia , Galván-Magaña Felipe , Abitia-Cárdenas Leonardo Andrés
Published: September 2015

Occupying the upper levels of trophic webs and thus regulating prey at lower levels, sharks play an important role in the trophic structure and energy dynamics of marine ecosystems. In recent years, the removal of these individuals from upper trophic levels as a result of overfishing has negatively affected ecosystems. We analysed the diet of blue sharks (Prionace glauca) caught off the west coast of Baja California Sur, Mexico, during the months of February–June in 2001, 2005 and 2006. We employed both stomach content and stable isotope analyses as each method provides distinct yet important information regarding the role of blue sharks in marine food webs, allowing us to estimate the relative contribution of different prey items to this predator's diet. Of the 368 stomachs analysed, 210 contained food (57%) and 158 (43%) were empty. Based on stomach contents and the index of relative importance (IRI), the pelagic red crab (Pleuroncodes planipes) was the most important prey, followed by the squids Gonatus californiensis (34.1%) and Ancistrocheirus lesueurii (10.4%). The mean (±SD) values for δ15N (16.48 ± 0.94‰) and δ13C (−18.48 ± 0.63‰) suggest that blue sharks prefer feeding in oceanic waters. The trophic level based on stomach content analysis was 4.05, while that based on the stable isotope analysis was 3.8, making blue sharks top consumers in the marine ecosystem of Baja California Sur, Mexico.
Personality traits and combat exposure as predictors of psychopathology over time
Authors: Koffel E. , Kramer M. D. , Arbisi P. A. , Erbes C. R. , Kaler M. , Polusny M. A.
Published: September 2015

Background.

Research suggests that personality traits have both direct and indirect effects on the development of psychological symptoms, with indirect effects mediated by stressful or traumatic events. This study models the direct influence of personality traits on residualized changes in internalizing and externalizing symptoms following a stressful and potentially traumatic deployment, as well as the indirect influence of personality on symptom levels mediated by combat exposure.

Method.

We utilized structural equation modeling with a longitudinal prospective study of 522 US National Guard soldiers deployed to Iraq. Analyses were based on self-report measures of personality, combat exposure, and internalizing and externalizing symptoms.

Results.

Both pre-deployment Disconstraint and externalizing symptoms predicted combat exposure, which in turn predicted internalizing and externalizing symptoms. There was a significant indirect effect for pre-deployment externalizing symptoms on post-deployment externalizing via combat exposure (p< 0.01). Negative Emotionality and pre-deployment internalizing symptoms directly predicted post-deployment internalizing symptoms, but both were unrelated to combat exposure. No direct effects of personality on residualized changes in externalizing symptoms were found.

Conclusions.

Baseline symptom dimensions had significant direct and indirect effects on post-deployment symptoms. Controlling for both pre-exposure personality and symptoms, combat experiences remained positively related to both internalizing and externalizing symptoms. Implications for diagnostic classification are discussed.
On the history of political diversity in social psychology
Authors: Binning Kevin R. , Sears David O.
Published: September 2015

We argue that the history of political diversity in social psychology may be better characterized by stability than by a large shift toward liberalism. The branch of social psychology that focuses on political issues has defined social problems from a liberal perspective since at least the 1930s. Although a lack of ideological diversity within the discipline can pose many of the problems noted by Duarte et al., we suggest that these problems (a) are less apparent when the insights of social psychology are pitted against the insights from other social science disciplines, and (b) are less pressing than the need for other types of diversity in the field, especially ethnic and racial diversity.
“Wait – You're a conservative?” Political diversity and the dilemma of disclosure
Authors: Everett Jim A. C.
Published: September 2015

Many of the proposed recommendations for remedying the harmful effects of political homogeneity for psychology depend upon conservatives disclosing their political identity. Yet how likely is this, when disclosure is so harmful to the individual? Considering this issue as a social dilemma clarifies the pernicious nature of the problem, as well as suggesting how the dilemma can be resolved.
Increasing ideological tolerance in social psychology
Authors: Inbar Yoel , Lammers Joris
Published: September 2015

We argue that recognizing current ideological diversity in social psychology and promoting tolerance of minority views is just as important as increasing the number of non-liberal researchers. Increasing tolerance will allow individuals in the minority to express dissenting views, which will improve psychological science by reducing bias. We present four recommendations for increasing tolerance.
Diversity of depoliticization?
Authors: van der Vossen Bas
Published: September 2015

An ideologically homogeneous discipline of political psychology is a serious problem. But undoing the field's homogeneity may not suffice to address this problem. Instead, we should consider undoing the politicization.
Political attitudes in social environments
Authors: Gelman Andrew , Gross Neil
Published: September 2015

We agree with Duarte et al. that it is worthwhile to study professions' political alignments. But we have seen no evidence to support the idea that social science fields with more politically diverse workforces generally produce better research. We also think that when considering ideological balance, it is useful to place social psychology within a larger context of the prevailing ideologies of other influential groups within society, such as military officers, journalists, and business executives.
Rage Against The Machine, Zapatismo, and the aesthetics of anger
Authors: Green Andrew
Published: September 2015

This article explores the ways in which anger may travel across different musical and extra-musical contexts, looking in particular at the rap metal band Rage Against The Machine (RATM). Focusing on this band's appropriation of expressions of anger found in a documentary film about the Zapatistas in Mexico, it suggests that RATM can be read as a politico-emotional project, channelling anger towards political resistance which is then performed through, and upon, the body. Just as performances of anger need discourse to be sustainable, so music can simultaneously entrain the listener into a certain modality of feeling and expressing, and embed this modality in a discursive rationale. However, anger is a deeply ambiguous emotion, and cannot be easily focused; it may transcend the constraints some seek to place on it, and travel quickly between discursive contexts. Such slippages mark the limits of anger, as well as its power.
‘We demand justice. We just getting started’: the constitutive rhetoric of 1Hood Media's hip-hop activism
Authors: Kumanyika Chenjerai
Published: September 2015

The hip-hop activism of Pittsburgh's 1Hood Media has been a key element of the success of several contemporary social justice campaigns, such as the 2010 Justice For Jordan Miles police brutality case. After offering some background on 1Hood Media and a discussion of constitutive rhetoric, this study offers a close reading of 1Hood's rhetorical appeal, focusing on the ways in which the audience is constituted as both collective and individual subjects whose participation in the narrative is essential to its closure. 1Hood Media's texts focus on a diverse range of victims of injustice who suffer at the hands of police brutality and murder, and other forms of systemic oppression. The villains in these narratives are institutional forces, such as racist police forces, or corrupt Wall Street banks. By focusing on music, lyrical and visual features of 1Hood's cultural products, this study contributes to studies of popular music, hip-hop, rhetoric and cultural politics.
BAAL/CUP Seminar 2014: Languages in the UK: Bridging the gap between the classroom and the community in language learning
Authors: Smith-Christmas Cassie
Published: September 2015

On 29 and 30 May 2014, this seminar was hosted at Lews Castle College, University of the Highlands and Islands and organised by BAAL member Dr Cassie Smith-Christmas. In total, there were 16 participants from 13 universities across the UK. A total of nine papers were delivered over the two days and an hour-long roundtable was held at the close of the seminar. Keynote speakers were Professor Rosamond Mitchell (University of Southampton) and Professor Wilson McLeod (University of Edinburgh). Professor Kenneth MacKinnon (University of Aberdeen) acted as keynote discussant.
First Person Singular: Building the road as we travel
Authors: Long Michael H.
Published: September 2015

After completing a law degree at the University of Birmingham when I was 20 and not really knowing what I wanted to do, except that it was not law, I became an English as a foreign language (EFL) teacher accidentally through signing up as a volunteer with the British United Nations Association (BUNA), roughly equivalent to the US Peace Corps. Instead of being dispatched to assist starving people through a remote third-world community development project, as I had naively expected, I was sent on a fast-paced, two-week English as a second language (ESL) teacher-training course at a well-known private language school, International House, on Shaftesbury Avenue, in the heart of London's West End. Then came a one-week BUNA ‘orientation’ course in the suburbs. A hundred-plus neophyte volunteers were lectured on how to deliver a baby, how to deal with snake bites, how to remove leeches using gasoline or matches (but not both), the importance of taking anti-malaria pills daily without fail (pills subsequently found to be 100% ineffective), and how to avoid schistosomiasis (snail fever). On the last day, I was informed that, contrary to what I had first been told, I would not after all be going to Afghanistan, but to Peru. A week later, I arrived in Lima, a bustling Latin-American metropolis with no shortage of mid-wives, no malaria, no snakes, no snails and not a leech in sight. In the face of pervasive poverty, corruption, violence, and illiteracy, I had been sent several thousand miles, with absolutely no understanding of how people learn languages and minimal understanding of how to teach them, to provide free English classes for the relatively wealthy, mostly middle-class faculty and students in the Faculty of Law of Peru's leading university, the Universidad Nacional Mayor de San Marcos.
Influenza virus surveillance in Argentina during the 2012 season: antigenic characterization, genetic analysis and antiviral susceptibility
Authors: BENEDETTI E. , DANIELS R. S. , PONTORIERO A. , RUSSO M. , AVARO M. , CZECH A. , CAMPOS A. , PERIOLO N. , GREGORY V. , McCAULEY J. W. , BAUMEISTER E. G.
Published: September 2015

The activity and circulation of influenza viruses in Argentina was studied during 2012 as part of the Argentinean Surveillance for Influenza and other Respiratory Viruses, in the context of Global Influenza Surveillance. The antigenicity and molecular characteristics of haemagglutinins (HA) of circulating influenza A and B viruses were analysed to assess the emergence of virus variants. Susceptibility to oseltamivir and zanamivir was evaluated by enzymatic assay and results were backed-up by sequencing of the neuraminidase (NA) genes. During the 2012 season, influenza virus circulation in Argentina was detected from weeks 24 to 51. The HA sequences of the studied A(H1N1)pdm09 subtype viruses segregated in a different genetic group compared to those identified during the 2009 pandemic, although they were still closely related antigenically to the vaccine virus A/California/07/2009. The HA sequences of the A(H3N2) viruses analysed fell into the A/Victoria/208/2009 clade, genetic group 3C. A mixed circulation of virus variants belonging to B/Victoria and B/Yamagata lineages was detected, with B/Victoria being dominant. All viruses tested were sensitive to oseltamivir and zanamivir except one. This isolate, an A(H1N1)pdm09 virus possessing the substitution NA-N295S, showed highly reduced inhibition by oseltamivir and reduced inhibition by zanamivir. Virological and epidemiological surveillance remains critical for detection of evolving influenza viruses.
A representation theorem for second-order functionals
Authors: JASKELIOFF MAURO , O'CONNOR RUSSELL
Published: September 2015

Representation theorems relate seemingly complex objects to concrete, more tractable ones. In this paper, we take advantage of the abstraction power of category theory and provide a datatype-generic representation theorem. More precisely, we prove a representation theorem for a wide class of second-order functionals which are polymorphic over a class of functors. Types polymorphic over a class of functors are easily representable in languages such as Haskell, but are difficult to analyse and reason about. The concrete representation provided by the theorem is easier to analyse, but it might not be as convenient to implement. Therefore, depending on the task at hand, the change of representation may prove valuable in one direction or the other. We showcase the usefulness of the representation theorem with a range of examples. Concretely, we show how the representation theorem can be used to prove that traversable functors are finitary containers, how coalgebras of a parameterised store comonad relate to very well-behaved lenses, and how algebraic effects might be implemented in a functional language.
Effect of Hybrid stage 1 procedure on ventricular function in infants with hypoplastic left heart syndrome
Authors: Kobayashi Daisuke , Natarajan Girija , Turner Daniel R. , Forbes Thomas J. , Delius Ralph E. , Walters Henry L. , Aggarwal Sanjeev
Published: September 2015

Objective

The effect of Hybrid stage 1 palliation for hypoplastic left heart syndrome on right ventricular function is unknown. We sought to compare right ventricular function in normal neonates and those with hypoplastic left heart syndrome before Hybrid palliation and to assess the effect of Hybrid palliation on right ventricular function, using the right ventricular myocardial performance index and the ratio of systolic and diastolic durations.

Methods

We carried out a retrospective review of echocardiographic data on 23 infants with hypoplastic left heart syndrome who underwent Hybrid palliation and 35 normal controls. Data were acquired before Hybrid and after Hybrid palliation – post 1, 0–4 days; post 2, 1 week; post 3, 2–3 weeks; post 4, 1–1.5 months following Hybrid palliation.

Results

Myocardial performance index and ratio of systolic and diastolic durations were higher in the pre-Hybrid hypoplastic left heart syndrome group (n=23) – 0.47±0.16 versus 0.25±0.07, p<0.001; 1.59±0.44 versus 1.09±0.14, p<0.0001 – compared with controls (n=35). There was no significant change in the myocardial performance index at any of the post-Hybrid time points. Ratio of systolic and diastolic durations increased significantly 2 weeks after Hybrid – post 3: 2.08±0.62 and post 4: 2.21±0.45 versus pre: 1.59±0.44, p=0.043 and 0.003. There were no significant differences in parameters between sub-groups of infants who died (n=10) and survivors (n=13).

Conclusions

Right ventricular myocardial performance index and ratio of systolic and diastolic durations were significantly higher in infants with hypoplastic left heart syndrome before intervention compared with controls. The ratio of systolic and diastolic durations increased significantly 2 weeks after Hybrid palliation. Our data suggest that infants with hypoplastic left heart syndrome have right ventricular dysfunction before intervention, which worsens over 2 weeks after Hybrid palliation.
Bridging thoracic endovascular aneurysm repair for a late rupture following aortic coarctation angioplasty
Authors: Oliveira Nelson F. G. , Castro João A. , Martins José D. , Quintas Anita , Laranjo Sérgio , Valentim Hugo , Pinto Fátima , Capitão Luís M.
Published: September 2015

Introduction

Thoracic endovascular aneurysm repair has been employed to treat late complications after aortic coarctation correction. However, its use in children has seldomly been reported.

Case report

We present the case of a 15-year-old child who presented with a ruptured aneurysm of the descending aorta complicated later by an aortic-oesophageal fistula following aortic coarctation stenting that was managed with multiple bridging endovascular interventions until a definitive repair was performed.

Conclusion

Thoracic endovascular aneurysm repair may be used successfully as a bridging intervention to a definitive repair in children with life-threatening aortic complications following aortic coarctation repair.
Effects of serotonin in the hippocampus: how SSRIs and multimodal antidepressants might regulate pyramidal cell function
Authors: Dale Elena , Pehrson Alan L. , Jeyarajah Theepica , Li Yan , Leiser Steven C. , Smagin Gennady , Olsen Christina K. , Sanchez Connie
Published: September 2015

The hippocampus plays an important role in emotional and cognitive processing, and both of these domains are affected in patients with major depressive disorder (MDD). Extensive preclinical research and the notion that modulation of serotonin (5-HT) neurotransmission plays a key role in the therapeutic efficacy of selective serotonin reuptake inhibitors (SSRIs) support the view that 5-HT is important for hippocampal function in normal and disease-like conditions. The hippocampus is densely innervated by serotonergic fibers, and the majority of 5-HT receptor subtypes are expressed there. Furthermore, hippocampal cells often co-express multiple 5-HT receptor subtypes that can have either complementary or opposing effects on cell function, adding to the complexity of 5-HT neurotransmission. Here we review the current knowledge of how 5-HT, through its various receptor subtypes, modulates hippocampal output and the activity of hippocampal pyramidal cells in rodents. In addition, we discuss the relevance of 5-HT modulation for cognitive processing in rodents and possible clinical implications of these results in patients with MDD. Finally, we review the data on how SSRIs and vortioxetine, an antidepressant with multimodal activity, affect hippocampal function, including cognitive processing, from both a preclinical and clinical perspective.
“PROTRACTED CONFLICT”
Authors: Platon Mircea Alexandru
Published: September 2015

Robert Strausz-Hupé (1903-2002) and Stefan Possony (1913-1995) were two scholars and policy makers who reached the peak of their careers as the tutelary spirits of the Foreign Policy Research Institute (FPRI), founded in 1955 at the University of Pennsylvania. Through the FPRI and its journal,Orbis, the influence of these two anti-”totalitarian” crusaders reached the high echelons of the United States military and U.S. policy makers. This article analyzes the way in which the intellectuals of the FPRI—“defense intellectuals”—tweaked concepts such as “human rights,” “freedom,” “democracy,” and “open society” in order to promote the interests of the United States’s military-industrial establishment, court racist lobbies, and accommodate problematic Cold War allies such as South Africa.
THE PHILADELPHIA NEGROAND THE CANON OF CLASSICAL URBAN THEORY
Authors: Loughran Kevin
Published: September 2015

This paper outlines the urban theory of W. E. B. Du Bois as presented in the classic sociological textThe Philadelphia Negro. I argue that Du Bois’s urban theory, which focused on how the socially-constructed racial hierarchy of the United States was shaping the material conditions of industrial cities, prefigured important later work and offered a sociologically richer understanding of urban processes than the canonized classical urban theorists—Weber, Simmel, and Park. I focus on two key areas of Du Bois’s urban theory: (1) racial stratification as a fundamental feature of the modern city and (2) urbanization and urban migration. WhileThe Philadelphia Negrohas gained recent praise for Du Bois’s methodological achievements, I use extensive passages from the work to demonstrate the theoretical importance ofThe Philadelphia Negroand to argue that this groundbreaking work should be considered canonical urban theory.
The ‘Developmental Origins’ Hypothesis: relevance to the obstetrician and gynecologist
Authors: Kermack A. J. , Van Rijn B. B. , Houghton F. D. , Calder P. C. , Cameron I. T. , Macklon N. S.
Published: September 2015

The recognition of ‘fetal origins of adult disease’ has placed new responsibilities on the obstetrician, as antenatal care is no longer simply about ensuring good perinatal outcomes, but also needs to plan for optimal long-term health for mother and baby. Recently, it has become clear that the intrauterine environment has a broad and long-lasting impact, influencing fetal and childhood growth and development as well as future cardiovascular health, non-communicable disease risk and fertility. This article looks specifically at the importance of the developmental origins of ovarian reserve and ageing, the role of the placenta and maternal nutrition before and during pregnancy. It also reviews recent insights in developmental medicine of relevance to the obstetrician, and outlines emerging evidence supporting a proactive clinical approach to optimizing periconceptional as well as antenatal care aimed to protect newborns against long-term disease susceptibility.
Understanding and Treatment of Chronic Abdominal Pain Among School Nurses: A National Survey
Authors: Deacy Amanda D. , Morrison Chelsey
Published: September 2015

School nurses often are the first (and most sustained) point of contact for children with medical issues and, as such, they are well poised to provide early intervention for children with chronic abdominal pain. Therefore, the current study sought to assess school nurses’ perspectives and practices related to chronic abdominal pain. A study invitation and link to a web-based questionnaire were sent to members of the National Association of School Nurses (NASN) with published e-mail addresses. A total of 1,550 school nurses (∼11% response rate) participated in the study. Approximately 1/3 of the sample reported >90 annual student visits for abdominal pain. Fifty-seven percent perceived the most common cause for childhood chronic abdominal pain as related to psychosocial issues. Although psychosocial issues were the most commonly perceived cause of pain, 66% of nurses reported collaborating with mental health professionals <10% of the time. Half of the nurses sampled were not confident in their understanding of chronic abdominal pain in children, and 27% perceived nursing education available on the topic to be nonexistent or poor. School nurses frequently see children with abdominal pain, primarily believe psychosocial/behavioral issues to account for it (although rarely collaborate with mental health professionals), and know little about biological contributors to and classification of the condition. These findings indicate a need for an evidence-based curriculum for school nurse training.
IRTKS negatively regulates antiviral immunity through PCBP2 sumoylation-mediated MAVS degradation
Authors: Xia Pengyan , Wang Shuo , Xiong Zhen , Ye Buqing , Huang Li-Yu , Han Ze-Guang , Fan Zusen
Published: September 2015

RNA virus infection is recognized by the RIG-I family of receptors that activate the mitochondrial adaptor MAVS, leading to the clearance of viruses. Antiviral signalling activation requires strict modulation to avoid damage to the host from exacerbated inflammation. Insulin receptor tyrosine kinase substrate (IRTKS) participates in actin bundling and insulin signalling and its deficiency causes insulin resistance. However, whether IRTKS is involved in the regulation of innate immunity remains elusive. Here we show that IRTKS deficiency causes enhanced innate immune responses against RNA viruses. IRTKS-mediated suppression of antiviral responses depends on the RIG-I-MAVS signalling pathway. IRTKS recruits the E2 ligase Ubc9 to sumoylate PCBP2 in the nucleus, which causes its cytoplasmic translocation during viral infection. The sumoylated PCBP2 associates with MAVS to initiate its degradation, leading to downregulation of antiviral responses. Thus, IRTKS functions as a negative modulator of excessive inflammation.
Returners and explorers dichotomy in human mobility
Authors: Pappalardo Luca , Simini Filippo , Rinzivillo Salvatore , Pedreschi Dino , Giannotti Fosca , Barabási Albert-László
Published: September 2015

The availability of massive digital traces of human whereabouts has offered a series of novel insights on the quantitative patterns characterizing human mobility. In particular, numerous recent studies have lead to an unexpected consensus: the considerable variability in the characteristic travelled distance of individuals coexists with a high degree of predictability of their future locations. Here we shed light on this surprising coexistence by systematically investigating the impact of recurrent mobility on the characteristic distance travelled by individuals. Using both mobile phone and GPS data, we discover the existence of two distinct classes of individuals: returners and explorers. As existing models of human mobility cannot explain the existence of these two classes, we develop more realistic models able to capture the empirical findings. Finally, we show that returners and explorers play a distinct quantifiable role in spreading phenomena and that a correlation exists between their mobility patterns and social interactions.
Carrier multiplication detected through transient photocurrent in device-grade films of lead selenide quantum dots
Authors: Gao Jianbo , Fidler Andrew F. , Klimov Victor I.
Published: September 2015

In carrier multiplication, the absorption of a single photon results in two or more electron–hole pairs. Quantum dots are promising materials for implementing carrier multiplication principles in real-life technologies. So far, however, most of research in this area has focused on optical studies of solution samples with yet to be proven relevance to practical devices. Here we report ultrafast electro-optical studies of device-grade films of electronically coupled quantum dots that allow us to observe multiplication directly in the photocurrent. Our studies help rationalize previous results from both optical spectroscopy and steady-state photocurrent measurements and also provide new insights into effects of electric field and ligand treatments on multiexciton yields. Importantly, we demonstrate that using appropriate chemical treatments of the films, extra charges produced by carrier multiplication can be extracted from the quantum dots before they are lost to Auger recombination and hence can contribute to photocurrent of practical devices.
Integrin-linked kinase regulates the niche of quiescent epidermal stem cells
Authors: Morgner Jessica , Ghatak Sushmita , Jakobi Tobias , Dieterich Christoph , Aumailley Monique , Wickström Sara A.
Published: September 2015

Stem cells reside in specialized niches that are critical for their function. Quiescent hair follicle stem cells (HFSCs) are confined within the bulge niche, but how the molecular composition of the niche regulates stem cell behaviour is poorly understood. Here we show that integrin-linked kinase (ILK) is a key regulator of the bulge extracellular matrix microenvironment, thereby governing the activation and maintenance of HFSCs. ILK mediates deposition of inverse laminin (LN)-332 and LN-511 gradients within the basement membrane (BM) wrapping the hair follicles. The precise BM composition tunes activities of Wnt and transforming growth factor-β pathways and subsequently regulates HFSC activation. Notably, reconstituting an optimal LN microenvironment restores the altered signalling in ILK-deficient cells. Aberrant stem cell activation in ILK-deficient epidermis leads to increased replicative stress, predisposing the tissue to carcinogenesis. Overall, our findings uncover a critical role for the BM niche in regulating stem cell activation and thereby skin homeostasis.
Phospho-selective mechanisms of arrestin conformations and functions revealed by unnatural amino acid incorporation and 19F-NMR
Authors: Yang Fan , Yu Xiao , Liu Chuan , Qu Chang-Xiu , Gong Zheng , Liu Hong-Da , Li Fa-Hui , Wang Hong-Mei , He Dong-Fang , Yi Fan , Song Chen , Tian Chang-Lin , Xiao Kun-Hong , Wang Jiang-Yun , Sun Jin-Peng
Published: September 2015

Specific arrestin conformations are coupled to distinct downstream effectors, which underlie the functions of many G-protein-coupled receptors (GPCRs). Here, using unnatural amino acid incorporation and fluorine-19 nuclear magnetic resonance (19F-NMR) spectroscopy, we demonstrate that distinct receptor phospho-barcodes are translated to specific β-arrestin-1 conformations and direct selective signalling. With its phosphate-binding concave surface, β-arrestin-1 ‘reads’ the message in the receptor phospho-C-tails and distinct phospho-interaction patterns are revealed by 19F-NMR. Whereas all functional phosphopeptides interact with a common phosphate binding site and induce the movements of finger and middle loops, different phospho-interaction patterns induce distinct structural states of β-arrestin-1 that are coupled to distinct arrestin functions. Only clathrin recognizes and stabilizes GRK2-specific β-arrestin-1 conformations. The identified receptor-phospho-selective mechanism for arrestin conformation and the spacing of the multiple phosphate-binding sites in the arrestin enable arrestin to recognize plethora phosphorylation states of numerous GPCRs, contributing to the functional diversity of receptors.
Transform-limited single photons from a single quantum dot
Authors: Kuhlmann Andreas V. , Prechtel Jonathan H. , Houel Julien , Ludwig Arne , Reuter Dirk , Wieck Andreas D. , Warburton Richard J.
Published: September 2015

Developing a quantum photonics network requires a source of very-high-fidelity single photons. An outstanding challenge is to produce a transform-limited single-photon emitter to guarantee that single photons emitted far apart in the time domain are truly indistinguishable. This is particularly difficult in the solid-state as the complex environment is the source of noise over a wide bandwidth. A quantum dot is a robust, fast, bright and narrow-linewidth emitter of single photons; layer-by-layer growth and subsequent nano-fabrication allow the electronic and photonic states to be engineered. This represents a set of features not shared by any other emitter but transform-limited linewidths have been elusive. Here, we report transform-limited linewidths measured on second timescales, primarily on the neutral exciton but also on the charged exciton close to saturation. The key feature is control of the nuclear spins, which dominate the exciton dephasing via the Overhauser field.
Sparsity-based super-resolved coherent diffraction imaging of one-dimensional objects
Authors: Sidorenko Pavel , Kfir Ofer , Shechtman Yoav , Fleischer Avner , Eldar Yonina C. , Segev Mordechai , Cohen Oren
Published: September 2015

Phase-retrieval problems of one-dimensional (1D) signals are known to suffer from ambiguity that hampers their recovery from measurements of their Fourier magnitude, even when their support (a region that confines the signal) is known. Here we demonstrate sparsity-based coherent diffraction imaging of 1D objects using extreme-ultraviolet radiation produced from high harmonic generation. Using sparsity as prior information removes the ambiguity in many cases and enhances the resolution beyond the physical limit of the microscope. Our approach may be used in a variety of problems, such as diagnostics of defects in microelectronic chips. Importantly, this is the first demonstration of sparsity-based 1D phase retrieval from actual experiments, hence it paves the way for greatly improving the performance of Fourier-based measurement systems where 1D signals are inherent, such as diagnostics of ultrashort laser pulses, deciphering the complex time-dependent response functions (for example, time-dependent permittivity and permeability) from spectral measurements and vice versa.
Global priorities for an effective information basis of biodiversity distributions
Authors: Meyer Carsten , Kreft Holger , Guralnick Robert , Jetz Walter
Published: September 2015

Gaps in digital accessible information (DAI) on species distributions hamper prospects of safeguarding biodiversity and ecosystem services, and addressing central ecological and evolutionary questions. Achieving international targets on biodiversity knowledge requires that information gaps be identified and actions prioritized. Integrating 157 million point records and distribution maps for 21,170 terrestrial vertebrate species, we find that outside a few well-sampled regions, DAI on point occurrences provides very limited and spatially biased inventories of species. Surprisingly, many large, emerging economies are even more under-represented in global DAI than species-rich, developing countries in the tropics. Multi-model inference reveals that completeness is mainly limited by distance to researchers, locally available research funding and participation in data-sharing networks, rather than transportation infrastructure, or size and funding of Western data contributors as often assumed. Our results highlight the urgent need for integrating non-Western data sources and intensifying cooperation to more effectively address societal biodiversity information needs.
Critical heat flux maxima during boiling crisis on textured surfaces
Authors: Dhillon Navdeep Singh , Buongiorno Jacopo , Varanasi Kripa K.
Published: September 2015

Enhancing the critical heat flux (CHF) of industrial boilers by surface texturing can lead to substantial energy savings and global reduction in greenhouse gas emissions, but fundamentally this phenomenon is not well understood. Prior studies on boiling crisis indicate that CHF monotonically increases with increasing texture density. Here we report on the existence of maxima in CHF enhancement at intermediate texture density using measurements on parametrically designed plain and nano-textured micropillar surfaces. Using high-speed optical and infrared imaging, we study the dynamics of dry spot heating and rewetting phenomena and reveal that the dry spot heating timescale is of the same order as that of the gravity and liquid imbibition-induced dry spot rewetting timescale. Based on these insights, we develop a coupled thermal-hydraulic model that relates CHF enhancement to rewetting of a hot dry spot on the boiling surface, thereby revealing the mechanism governing the hitherto unknown CHF enhancement maxima.
A Simple and Sensitive Method to Quantify Biodegradable Nanoparticle Biodistribution using Europium Chelates
Authors: Crawford Lindsey , Higgins Jaclyn , Putnam David
Published: September 2015

The biodistribution of biodegradable nanoparticles can be difficult to quantify. We report a method using time resolved fluorescence (TRF) from a lanthanide chelate to minimize background autofluorescence and maximize the signal to noise ratio to detect biodegradable nanoparticle distribution in mice. Specifically, antenna chelates containing europium were entrapped within nanoparticles composed of polylactic acid-polyethylene glycol diblock copolymers. Tissue accumulation of nanoparticles following intravenous injection was quantified in mice. The TRF of the nanoparticles was found to diminish as a second order function in the presence of serum and tissue compositions interfered with the europium signal. Both phenomena were corrected by linearization of the signal function and calculation of tissue-specific interference, respectively. Overall, the method is simple and robust with a detection limit five times greater than standard fluorescent probes.
Structural and Thermodynamic Characteristics of Amyloidogenic Intermediates of β-2-Microglobulin
Authors: Chong Song-Ho , Hong Jooyeon , Lim Sulgi , Cho Sunhee , Lee Jinkeong , Ham Sihyun
Published: September 2015

β-2-microglobulin (β2m) self-aggregates to form amyloid fibril in renal patients taking long-term dialysis treatment. Despite the extensive structural and mutation studies carried out so far, the molecular details on the factors that dictate amyloidogenic potential of β2m remain elusive. Here we report molecular dynamics simulations followed by the solvation thermodynamic analyses on the wild-type β2m and D76N, D59P and W60C mutants at the native (N) and so-called aggregation-prone intermediate (IT) states, which are distinguished by the native cis- and non-native trans-Pro32 backbone conformations. Three major structural and thermodynamic characteristics of the IT-state relative to the N-state in β2m protein are detected that contribute to the increased amyloidogenic potential: (i) the disruption of the edge D-strand, (ii) the increased solvent-exposed hydrophobic interface and (iii) the increased solvation free energy (less affinity toward solvent water). Mutation effects on these three factors are shown to exhibit a good correlation with the experimentally observed distinct amyloidogenic propensity of the D76N (+), D59P (+) and W60C (−) mutants (+/− for enhanced/decreased). Our analyses thus identify the structural and thermodynamic characteristics of the amyloidogenic intermediates, which will serve to uncover molecular mechanisms and driving forces in β2m amyloid fibril formation.
EXTL2 and EXTL3 inhibition with siRNAs as a promising substrate reduction therapy for Sanfilippo C syndrome
Authors: Canals Isaac , Benetó Noelia , Cozar Mónica , Vilageliu Lluïsa , Grinberg Daniel
Published: September 2015

Sanfilippo syndrome is a rare lysosomal storage disorder caused by an impaired degradation of heparan sulfate (HS). It presents severe and progressive neurodegeneration and currently there is no effective treatment. Substrate reduction therapy (SRT) may be a useful option for neurological disorders of this kind and several approaches have been tested to date. Here we use different siRNAs targeting EXTL2 and EXTL3 genes, which are important for HS synthesis, as SRT in Sanfilippo C patients’ fibroblasts in order to decrease glycosaminoglycan (GAG) storage inside the lysosomes. The results show a high inhibition of the EXTL gene mRNAs (around 90%), a decrease in GAG synthesis after three days (30–60%) and a decrease in GAG storage after 14 days (up to 24%). Moreover, immunocytochemistry analyses showed a clear reversion of the phenotype after treatment. The in vitro inhibition of HS synthesis genes using siRNAs shown here is a first step in the development of a future therapeutic option for Sanfilippo C syndrome.
Developing high energy dissipative soliton fiber lasers at 2 micron
Authors: Huang Chongyuan , Wang Cong , Shang Wei , Yang Nan , Tang Yulong , Xu Jianqiu
Published: September 2015

While the recent discovered new mode-locking mechanism - dissipative soliton - has successfully improved the pulse energy of 1 μm and 1.5 μm fiber lasers to tens of nanojoules, it is still hard to scale the pulse energy at 2 μm due to the anomalous dispersion of the gain fiber. After analyzing the intracavity pulse dynamics, we propose that the gain fiber should be condensed to short lengths in order to generate high energy pulse at 2 μm. Numerical simulation predicts the existence of stable 2 μm dissipative soliton solutions with pulse energy over 10 nJ, comparable to that achieved in the 1 μm and 1.5 μm regimes. Experimental operation confirms the validity of the proposal. These results will advance our understanding of mode-locked fiber lasers at different wavelengths and lay an important step in achieving high energy ultrafast laser pulses from anomalous dispersion gain media.
New insight into the residual inactivation of Microcystis aeruginosa by dielectric barrier discharge
Authors: Li Lamei , Zhang Hong , Huang Qing
Published: September 2015

We report the new insight into the dielectric barrier discharge (DBD) induced inactivation of Microcystis aeruginosa, the dominant algae which caused harmful cyanobacterial blooms in many developing countries. In contrast with the previous work, we employed flow cytometry to examine the algal cells, so that we could assess the dead and living cells with more accuracy and distinguish an intermediate state of algal cells which were verified as apoptotic. Our results showed that the numbers of both dead and apoptotic cells increased with DBD treatment delay time and hydrogen peroxide produced by DBD was the main reason for the time-delayed inactivation effect. However, apart from the influence of hydrogen peroxide, the DBD-induced initial injures on the algal cells during the discharge period also played a considerable role in the inactivation of the DBD treated cells, as indicated by the measurement of intracellular reactive oxygen species (ROS) inside the algal cells. We therefore propose an effective approach to utilization of non-thermal plasma technique that makes good use of the residual inactivation effect to optimize the experimental conditions in terms of discharge time and delay time, so that more efficient treatment of cyanobacterial blooms can be achieved.
Functionalized Buckyballs for Visualizing Microbial Species in Different States and Environments
Authors: Cheng Qingsu , Aravind Ashwin , Buckley Matthew , Gifford Andrew , Parvin Bahram
Published: September 2015

To date,in situvisualization of microbial density has remained an open problem. Here, functionalized buckyballs (e.g., C60-pyrrolidine tris acid) are shown to be a versatile platform that allows internalization within a microorganism without either adhering to the cell wall and cell membrane or binding to a matrix substrate such as soil. These molecular probes are validated via multi-scale imaging, to show association with microorganisms via fluorescence microscopy, positive cellular uptake via electron microscopy and non-specific binding to the substrates through a combination of fluorescence and autoradiography imaging. We also demonstrate that cysteine-functionalized C60-pyrrolidine tris acid can differentiate live and dead microorganisms.
Probing Spin Accumulation induced Magnetocapacitance in a Single Electron Transistor
Authors: Lee Teik-Hui , Chen Chii-Dong
Published: September 2015

The interplay between spin and charge in solids is currently among the most discussed topics in condensed matter physics. Such interplay gives rise to magneto-electric coupling, which in the case of solids was named magneto-electric effect, as predicted by Curie on the basis of symmetry considerations. This effect enables the manipulation of magnetization using electrical field or, conversely, the manipulation of electrical polarization by magnetic field. The latter is known as the magnetocapacitance effect. Here, we show that non-equilibrium spin accumulation can induce tunnel magnetocapacitance through the formation of a tiny charge dipole. This dipole can effectively give rise to an additional serial capacitance, which represents an extra charging energy that the tunneling electrons would encounter. In the sequential tunneling regime, this extra energy can be understood as the energy required for a single spin to flip. A ferromagnetic single-electron-transistor with tunable magnetic configuration is utilized to demonstrate the proposed mechanism. It is found that the extra threshold energy is experienced only by electrons entering the islands, bringing about asymmetry in the measured Coulomb diamond. This asymmetry is an unambiguous evidence of spin accumulation induced tunnel magnetocapacitance and the measured magnetocapacitance value is as high as 40%.