bluuebunny/crossref_metadata_2025 huggingface dataset:
The establishment of large private nature reserves by conservation NGOs: key factors for successful implementation
Authors: Pasquini Lorena , Fitzsimons James A. , Cowell Stuart , Brandon Katrina , Wescott Geoff
Published: June 2011

Private nature reserves created by non-governmental organizations (NGOs) are increasing, and their growing number and extent means that they can potentially contribute to biodiversity goals at a global scale. However, the success of these reserves depends on the legal, economic and institutional conditions framing their creation and management. We explored these conditions, and the opportunities and challenges facing conservation organizations in managing private nature reserves, across several countries, with an emphasis on Australia. Results from 17 semi-structured interviews with representatives of private conservation organizations indicated that while private reserves may enhance the conservation estate, challenges remain. Legal frameworks, especially tenure and economic laws, vary across and within countries, presenting conservation organizations with significant opportunities or constraints to owning and/or managing private nature reserves. Many acquired land without strategic acquisition procedures and secured funding for property acquisition but not management, affecting the long-term maintenance of properties. Other typical problems were tied to the institutional capacity of the organizations. Greater planning within organizations, especially financial planning, is required and NGOs must understand opportunities and constraints present in legislative frameworks at the outset. Organizations must establish their expertise gaps and address them. To this end, partnerships between organizations and/or with government can prove critical.
Status and conservation of the only population of the Vulnerable owl-faced monkey Cercopithecus hamlyni in Rwanda
Authors: Easton Julian , Chao Nerissa , Mulindahabi Felix , Ntare Nicolas , Rugyerinyange Louis , Ndikubwimana Innocent
Published: June 2011

The elusive, Vulnerable owl-faced monkey Cercopithecus hamlyni is a rare and little studied species and one of the least known of the African Cercopithecidae. This study describes the distribution and relative abundance of the only known population in East Africa, in Nyungwe National Park, Rwanda. This species is restricted to a small (32 km2) area of bamboo and bamboo–forest mix in the southern sector of the Park, close to the international border with Burundi. We present the first empirical data of its abundance in the bamboo forests of Nyungwe. A total length of 185 km of transect were surveyed to estimate relative abundance of diurnal primates. Encounter rates with the owl-faced monkey were 0.081 groups km-1 (n = 15). Mean group size was 3.6 individuals. Eight independent photographs of C. hamlyni were obtained from five camera traps during 182 camera-days. Four other species of primates occur in the bamboo forest: eastern chimpanzee Pan troglodytes schweinfurthii, Angola colobus Colobus angolensis, L’Hoest’s monkey Cercopithecus l’hoesti and blue monkey Cercopithecus mitis. The main threats to the bamboo forest are from the illegal harvesting of bamboo, trapping and tree-cutting. These threats originate from both Rwanda and Burundi. There is an urgent need for conservation action to halt the destruction and degradation of the bamboo forest and to ensure the long-term survival of the owl-faced monkey in Rwanda.
Another inconvenient truth: the failure of enforcement systems to save charismatic species
Authors: Bennett Elizabeth L.
Published: June 2011

In spite of significant recent advances in understanding how to conserve species we are failing to conserve some of the most beloved and charismatic, with severe population losses, shrinking ranges and extinctions of subspecies. The primary reason is hunting for illegal trade of highly valuable body parts, increasingly operated by sophisticated organized criminal syndicates supplying wealthy East Asian markets. Current enforcement systems were not established to tackle such crime, and weak governance, low capacity and inadequate resources facilitate the trade. To save these species this trade must be treated as serious crime, with allocation of sufficient resources, highly trained personnel, and appropriate technologies to allow it to be tackled effectively. Success in tackling this trade will necessitate commitment from governments and non-governmental organizations and the support of civil society.
Watch-Keeping on Fishing Vessels: Can Electronic Marine Systems Help?
Authors: Mills Stella
Published: June 2011

Human watch-keeping is necessary to prevent incidents at sea such as groundings and collisions. For many years, electronic aids to navigation have been utilised in watch-keeping but, with electronic marine systems becoming more sophisticated, the part they play in preventing collisions and groundings should become increasingly important. However, this article uses secondary data from the Safety Digest for 2008 compiled by the Marine Accident Investigation Bureau of the United Kingdom; eight case studies are used to show that electronic marine systems, whether integrated or not, are still playing a part in poor watch-keeping resulting in collisions, near misses and groundings. Primary data from fishing skippers of British based vessels have been used to confirm the findings from the secondary data that poor watch-keeping is often the cause of not keeping a proper lookout and that the watch-keeper has a too heavy reliance on the electronic aids. Brief suggestions are made as to how the electronic aids may be adapted to overcome these problems and thus to support the watch-keeper.
Accurate Harmonic Series for Inverse and Direct Solutions for the Great Ellipse
Authors: Earle Michael A.
Published: June 2011

In this paper, formulae drawn from the discipline of map projections are applied to provide simple and accurate solutions for the Inverse and Direct problems on the Great Ellipse. Distance along the meridional arc of the spheroid as a function of geodetic latitude is defined in terms of an elliptic integral which will be replaced here with a compact harmonic series approximation possessing simplicity and high accuracy. Latitude as a function of distance along the meridional arc will also be obtained via another equally simple inversion series that also possesses high accuracy. When these two series are applied with their constants modified to suit the section ellipse, they will be shown to provide accurate solutions to the inverse and direct navigation problems pertaining to the Great Ellipse, and thereby provide a complete solution that is also simple to implement.
Shadow Matching: A New GNSS Positioning Technique for Urban Canyons
Authors: Groves Paul D.
Published: June 2011

The Global Positioning System (GPS) is unreliable in dense urban areas, known as urban canyons, which have tall buildings or narrow streets. This is because the buildings block the signals from many of the satellites. Combining GPS with other Global Navigation Satellite Systems (GNSS) significantly increases the availability of direct line-of-sight signals. Modelling is used to demonstrate that, although this will enable accurate positioning along the direction of the street, the positioning accuracy in the cross-street direction will be poor because the unobstructed satellite signals travel along the street, rather than across it. A novel solution to this problem is to use 3D building models to improve cross-track positioning accuracy in urban canyons by predicting which satellites are visible from different locations and comparing this with the measured satellite visibility to determine position. Modelling is used to show that this shadow matching technique has the potential to achieve metre-order cross-street positioning in urban canyons. The issues to be addressed in developing a robust and practical shadow matching positioning system are then discussed and solutions proposed.
Maritime Safety Standards and the Seriousness of Shipping Accidents
Authors: Baniela Santiago Iglesias , Ríos Juan Vinagre
Published: June 2011

In our paper The Risk Homeostasis Theory1, it was accepted that the behaviour of people involved in the operation of cargo carrying ships is conditioned to maximize the economic benefits of the amount of risk assumed in the transport. As a follow-up to that paper, the objective of this one is to investigate the relationship between the level of compliance of the cargo carrying vessels with international standards and the degree of severity of the incidents they are involved in. For this purpose, we analyse the same sample of 2,584 cargo carrying ships involved in incidents during 2005 and 2006 used in that investigation. The variables of the Paris MoU to identify substandard ships are used again to measure the standard level of ships and the degree of seriousness of incidents is determined by the number of days ships are under repair.
Bering Sea Ice Cover in the Years 1998/9–2007/8
Authors: Trzeciak Stefan , Siódmak Szymon
Published: June 2011

The paper presents the Bering Sea ice cover data referring to the period from 1998/9 to 2007/8. Vessels' operational problems in that area are indicated. The traffic is discussed, with vessels divided into two basic groups. The authors attempt to explain why ice covers mainly the eastern and northern part of the sea and define the maximum ice extent in the decade under consideration. This study is based on selected data available on the website of the National Ice Center [6].
A multi-tiered time-series modelling approach to forecasting respiratory syncytial virus incidence at the local level
Authors: SPAEDER M. C. , FACKLER J. C.
Published: June 2011

Respiratory syncytial virus (RSV) is the most common cause of documented viral respiratory infections, and the leading cause of hospitalization, in young children. We performed a retrospective time-series analysis of all patients aged <18 years with laboratory-confirmed RSV within a network of multiple affiliated academic medical institutions. Forecasting models of weekly RSV incidence for the local community, inpatient paediatric hospital and paediatric intensive-care unit (PICU) were created. Ninety-five percent confidence intervals calculated around our models' 2-week forecasts were accurate to ±9·3, ±7·5 and ±1·5 cases/week for the local community, inpatient hospital and PICU, respectively. Our results suggest that time-series models may be useful tools in forecasting the burden of RSV infection at the local and institutional levels, helping communities and institutions to optimize distribution of resources based on the changing burden and severity of illness in their respective communities.
Mild Cognitive Impairment in the Elderly
Authors: Engmann Birk
Published: June 2011

The article reviews the relationship between depressive symptoms and mild cognitive impairment (MCI). Evidence bearing on this relation comes from clinical findings, neuroimaging, and cerebrospinal fluid markers. Depression in elderly people is associated with a higher occurrence of cognitive impairment, whereas the decline of cognitive functions over time seems to be a predictor of the development of dementia. Further symptoms predicting a high risk of progression from MCI to dementia are anxiety, restlessness, and low awareness of cognitive malfunction. There are controversies in the literature, however, about the connections among vascular brain lesions, depression, and MCI. Frontal and temporal brain regions seem to be at the core of functional changes in MCI patients. Several studies of cerebrospinal fluid point out the role of tau protein in predicting the outcome of MCI over time. In conclusion, diagnosis of MCI demands a complex assessment. MCI patients with and without depression need careful follow-up investigations.
Neural Correlates of Executive Dysfunction in Prodromal and Manifest Alzheimer’s Disease
Authors: Hunt Aoife , Haberkorn Uwe , Schröder Johannes , Schönknecht Peter
Published: June 2011

Executive function is frequently impaired in patients with Alzheimer’s disease (AD) and its prodromal stage, and can be assessed using the Trail-Making Test (TMT). We aimed to elicit the neural and cognitive correlates of TMT subtests using positron emission tomography with 18-fluoro-D-deoxy-glucose, and neuropsychological testing in 20 patients with prodromal or manifest AD as well as 14 controls. TMT-A correlated with glucose metabolism in the left middle frontal cortex, TMT-B performance correlated with the metabolism in the right middle frontal cortex and the right precentral gyrus, and TMT-Q performance correlated with metabolism in the right middle frontal cortex. The present findings reveal functional imaging evidence that executive dysfunction in AD as measured by TMT is frontal lobe mediated.
Psychometrische Charakteristika der deutschen Version des Young Adult Self-Report (YASR)
Authors: Agrez Urska , Winkler Metzke Christa , Steinhausen Hans-Christoph
Published: June 2011

Zusammenfassung. Der Young Adult Self-Report (YASR) erfasst behaviorale und emotionale Symptome bei jungen Erwachsenen im Alter von 18 bis 30 Jahre. Das Hauptziel der vorliegenden Studie war die Überprüfung der psychometrischen Qualität der deutschen Version des YASR auf der Basis von Daten aus einer großen epidemiologischen Stichprobe junger Erwachsener in der Schweiz (N = 951; Durchschnittsalter = 19.8, SD = 1.6; 56.3% Frauen). Die syndromale Struktur der amerikanischen Originalversion wurde in den Stichprobendaten mittels konfirmatorischer Faktorenanalyse gut repliziert. Mit Ausnahme der Skala Schizoid/zwanghaftes Denken sind alle Skalen für Forschungszwecke ausreichend zuverlässig. Aufgrund mangelnder interner Konsistenz einzelner Skalen müssen individuelle Testergebnisse mit Vorsicht interpretiert werden.
Hypochondrische Merkmale bei Patienten einer psychotherapeutischen Ambulanz
Authors: Weck Florian , Harms Gesa , Neng Julia M. B. , Stangier Ulrich
Published: June 2011

Zusammenfassung. Theoretischer Hintergrund: Während die Hypochondrie eine relativ niedrige Prävalenz aufweist, gibt es Hinweise, dass hypochondrische Merkmale unterhalb der diagnostischen Schwelle deutlich häufiger vorliegen. Fragestellung: Wie häufig bestehen bei ambulanten Psychotherapiepatienten ausgeprägte hypochondrische Merkmale? Kann die hypochondrische Symptomatik durch bestehende somatische Krankheiten erklärt werden? Welche Risikofaktoren könnten bedeutsam sein? Methode: 85 Patienten einer psychotherapeutischen Ambulanz wurden hinsichtlich des Vorliegens hypochondrischer Merkmale, Krankheitserfahrungen und traumatischer Erfahrungen in der Kindheit untersucht. Ergebnisse: Je nach Cut-off-Kriterium zeigten sich bei 24–34% der Patienten ausgeprägte krankheitsbezogene Befürchtungen, die in geringem Umfang (6–10%) durch einen schlechteren Gesundheitsstatus erklärt werden konnten. Potenziell relevant für hypochondrische Symptome zeigte sich zudem die Anzahl verstorbener Familienangehöriger. Schlussfolgerung: Hypochondrische Merkmale sollten in der ambulanten psychotherapeutischen Versorgung eine größere Beachtung finden, da sie von den Patienten häufig berichtet werden.
CD4 T cells play important roles in maintaining IL‐17‐producing γδ T‐cell subsets in naive animals
Authors: Do Jeong‐Su , Visperas Anabelle , O'Brien Rebecca L , Min Booki
Published: June 2011

A proportional balance between αβ and γδ T‐cell subsets in the periphery is exceedingly well maintained by a homeostatic mechanism. However, a cellular mechanism underlying the regulation remains undefined. We recently reported that a subset of developing γδ T cells spontaneously acquires interleukin (IL)‐17‐producing capacity even within naive animals through a transforming growth factor (TGF)β1‐dependent mechanism, thus considered ‘innate’ IL‐17‐producing cells. Here, we report that γδ T cells generated within αβ T cell (or CD4 T cell)‐deficient environments displayed altered cytokine profiles; particularly, ‘innate’ IL‐17 expression was significantly impaired compared with those in wild‐type mice. Impaired IL‐17 production in γδ T cells was directly related to CD4 T‐cell deficiency, because depletion of CD4 T cells in wild‐type mice diminished and adoptive CD4 T‐cell transfer into T‐cell receptor β−/− mice restored IL‐17 expression in γδ T cells. CD4 T cell‐mediated IL‐17 expression required TGFβ1. Moreover, Th17 but not Th1 or Th2 effector CD4 T cells were highly efficient in enhancing γδ T‐cell IL‐17 expression. Taken together, our results highlight a novel CD4 T cell‐dependent mechanism that shapes the generation of IL‐17+ γδ T cells in naive settings.
Local statistics in natural scenes predict the saliency of synthetic textures
Authors: Tkacik Gasper , Prentice Jason , Victor Jonathan , Balasubramanian Vijay
Published: June 2011

To represent behaviorally relevant information efficiently, neural circuits in sensory periphery are matched to the first and second-order statistical structure of natural inputs. The retina, for example, removes stimulus components that are predictable (and therefore uninformative), and transmits what is unpredictable (and therefore informative). Here we show that this efficient coding principle applies to complex aspects of natural scenes, and to central visual processing (Tkačik et al, PNAS 2010).The aspect of natural scenes that we examine in detail is texture in image patches. Texture is determined partly by the distribution of light intensities and partly by the spatial organization of light across pixels. To characterize these high-order natural image statistics we use two complementary dimensionality-reduction approaches. For intensity distributions, we analyze spatial variations in local intensity histograms. For local spatial organization of light, we analyze fourth-order correlations of nearby pixels. These approaches robustly classify image statistics according to their informativeness about the local structure of natural images.Remarkably, in both cases, we find that the distinction between informative vs. uninformative high-order statistics corresponds closely to the perceptual sensitivities of the human visual system documented in psychophysical measurements. For intensity distributions, the three most informative histogram statistics of natural images correspond to the three mechanisms that account for perception of spatially unstructured (“independent, identically-distributed”) artificial textures, namely, mean, variance, and a quantity known as “blackshot”. For spatial organization, we find that fourth-order spatial correlations that are informative correspond to those fourth-order correlations that are visually salient. Moreover, sensitivity to the latter high-order correlations is known to arise in visual cortex. Our results suggest that the principle of efficient coding also shapes later stages of sensory processing that are sensitive to high-order image statistics.
Taxometric Analyses of Specific Language Impairment in 6-Year-Old Children
Authors: Dollaghan Christine A.
Published: June 2011

Purpose

To determine whether language scores at age 6 years suggest that specific language impairments (SLIs) distribute in a categorical or in a dimensional fashion.

Method

A taxometric analysis of language scores from 601 six-year-old children who were free of neonatal risk factors was performed. From among 4 candidate indicators of SLI, 2 were eligible for the mean above minus below a cut (MAMBAC) procedure (Meehl & Yonce, 1994): number of different words (NDW) produced in a language sample and average percentage phonemes repeated correctly in 3- and 4-syllable nonwords (3–4 PPC). Graphs of these MAMBAC variables were inspected to determine whether they patterned in a manner suggesting the presence of a discrete category, having either a central peak or a steep curve peaking near the final interval.

Results

MAMBAC curves for NDW and 3–4 PPC did not suggest the presence of a taxon, and results did not vary during consistency checks in which MAMBAC parameters and cutoff values for language deficits were manipulated.

Conclusions

Results suggest that for these measures, children with specific language deficits are those falling at the lower end of a continuous distribution of language skills rather than a qualitatively distinct group.
Optical resonances in a composite asymmetric plasmonic nanostructure
Authors: Huang Wan-xia , Wang Qian-jin , Yin Xiao-gang , Huang Cheng-ping , Huang Huang , Wang Yu-min , Zhu Yong-yuan
Published: June 2011

The optical properties of a composite metamaterial, composed of asymmetric split-ring resonators (SRR) inserted into the periodic circular holes, have been investigated both experimentally and theoretically. Transmission peaks and dip associated with the localized plasmon excitations have been found: the peaks originate from the resonances of the smaller or bigger SRR, and the dip stems from the strong coupling between them. To understand the results, a composite LC circuit model has been employed.
Magnetic inhomogeneities and spin reorientation dependent magnetoresistance in HoNi5 thin films
Authors: Singh Gyanendra , Joshi P. C. , Budhani R. C.
Published: June 2011

We report measurements of electrical resistivity and magnetization in thin films of HoNi5 grown on (100) MgO substrate by means of pulsed laser deposition technique. These films are polycrystalline with a typical grain size of ≈10 nm and a random grain orientation. The temperature dependence of the electrical resistivity ρ(T) of the films reflects a metallic character down to ≈35 K, followed by a minimum at ≈30 K and then a rise at still lower temperatures, which is truncated by a cusp at T ≈ 3.5 K. We identify this feature with the Curie temperature (TCurie) of the film and confirm it through measurement of magnetization as a function of temperature. The magnetoresistance R(H) of the films for in-plane field at T < TCurie show some characteristic discontinuities which suggest an inhomogeneous magnetic state of the film and field driven spin reorientation transition.
The effects of Bi alloying in Cu delafossites: A density functional theory study
Authors: Huda Muhammad N. , Yan Yanfa , Al-Jassim Mowafak M.
Published: June 2011

Recently, Cu delafossites, CuMO2, have received much attention as photo-catalysts for hydrogen production by water splitting due to their unique properties such as stability in most aqueous solutions and p-type conductivity with excellent hole mobility. However, due to their large optical bandgaps, they can absorb sun light only in the ultraviolet region. Hence, it is necessary to tailor their optical properties to enhance their optical absorption in the visible light regions. In this paper, we report on the effects of Bi alloying on the electronic and optical properties of Cu delafossites by density functional theory. We find that Bi alloying can lead to improved optical absorption as compared to the pristine Cu delafossites. We further find that the lone pair Bi-6s electrons create occupied delocalized anti-bonding states on the top of the valence band, leading to further improved hole mobility.
Stability of ferromagnetism against doping in half-metallic alloys
Authors: Galanakis I. , Şaşıoğlu E.
Published: June 2011

We use a rigid band model to simulate doping in half-metallic NiMnSb and CoMnSb semi-Heusler alloys. Using first-principles calculations we calculate the intrasublattice exchange constants and the Curie temperature for these alloys as a function of the shift of the Fermi level and compare them also with the case of half-metallic CrAs and CrSe zinc-blende alloys. We show for all four compounds that the interactions between Cr-Cr(Mn-Mn) nearest neighbors are sufficient to explain the behavior of the Curie temperature. The interplay between the ferromagnetic RKKY-like and the antiferromagnetic superexchange interactions depends strongly on the details of the density of states around the minority-spin gap and thus it is found to be alloy-dependent.
First principles study of native defects in InI
Authors: Biswas Koushik , Du Mao-Hua
Published: June 2011

Heavy-metal halide semiconductors have attracted much interest recently for their potential applications in radiation detection because the large atomic numbers (high Z) of their constituent elements enable efficient radiation absorption and their large band gaps allow room temperature operation. However, defect properties of these halides and their connection to carrier transport are little known. In this paper, we present first-principles calculations on native defects in InI, which is a promising material for applications in room temperature radiation detection. The important findings are: (1) anion and cation vacancies (Schottky defects) form the dominant low-energy defects that can pin the Fermi level close to midgap, leading to high resistivity that is required for a good radiation detector material; (2) the anion vacancy in InI induces a deep electron trap, which should reduce electron mobility-lifetime product in InI; (3) low diffusion barriers of vacancies could be responsible for the observed polarization phenomenon at room temperature.
Semimetal to semiconductor transition and thermoelectric properties of bismuth nanotubes
Authors: Zhou G. , Li L. , Li G. H.
Published: June 2011

We have theoretically investigated the electronic subband structures and thermoelectric transport properties of Bi nanotubes. The calculated semimetal to semiconductor transition in Bi nanotubes is in good agreement with experiment results. The expressions for Seebeck coefficient and the optimized carrier concentration are first derived, and have been used to explain the calculated and experimental results. The effects of thickness, diameter, and growth direction of Bi nanotubes and carrier concentration on the thermoelectric figure of merit (ZT) are discussed. It was found that the Bi nanotube oriented along the trigonal direction has the highest ZT, and the optimized carrier concentration is found to be in a range from 1018 cm−3 to 4.0 × 1018 cm−3. The predicted enhancement in ZT is important for the anticipated applications of Bi nanotubes for thermoelectric devices.
Localization potentials in AlGaN epitaxial films studied by scanning near-field optical spectroscopy
Authors: Pinos A. , Liuolia V. , Marcinkevičius S. , Yang J. , Gaska R. , Shur M. S.
Published: June 2011

Scanning near-field photoluminescence spectroscopy has been applied to evaluate bandgap fluctuations in epitaxial AlGaN films with the AlN molar fraction varying from 0.30 to 0.50. A dual localization pattern has been observed. The potential of the small-scale (<100 nm) localization, evaluated from the width of the photoluminescence spectra, is between 0 and 51 meV and increases with increased Al content. These potential variations have been assigned to small-scale compositional fluctuations occurring due to stress variations, dislocations, and formation of Al-rich grains during growth. Larger area potential variations of 25–40 meV, most clearly observed in the lower Al-content samples, have been attributed to Ga-rich regions close to grain boundaries or atomic layer steps. The density, size, and bandgap energy of these domains were found to be composition dependent. The lower bandgap domains were found to be strongly correlated with the regions with efficient nonradiative recombination.
Correlating anomalous diffusion with lipid bilayer membrane structure using single molecule tracking and atomic force microscopy
Authors: Skaug Michael J. , Faller Roland , Longo Marjorie L.
Published: June 2011

Anomalous diffusion has been observed abundantly in the plasma membrane of biological cells, but the underlying mechanisms are still unclear. In general, it has not been possible to directly image the obstacles to diffusion in membranes, which are thought to be skeleton bound proteins, protein aggregates, and lipid domains, so the dynamics of diffusing particles is used to deduce the obstacle characteristics. We present a supported lipid bilayer system in which we characterized the anomalous diffusion of lipid molecules using single molecule tracking, while at the same time imaging the obstacles to diffusion with atomic force microscopy. To explain our experimental results, we performed lattice Monte Carlo simulations of tracer diffusion in the presence of the experimentally determined obstacle configurations. We correlate the observed anomalous diffusion with obstacle area fraction, fractal dimension, and correlation length. To accurately measure an anomalous diffusion exponent, we derived an expression to account for the time-averaging inherent to all single molecule tracking experiments. We show that the length of the single molecule trajectories is critical to the determination of the anomalous diffusion exponent. We further discuss our results in the context of confinement models and the generating stochastic process.
High-performance quantum cascade lasers with wide electroluminescence (∼600 cm−1), operating in continuous-wave above 100 °C
Authors: Fujita Kazuue , Furuta Shinichi , Sugiyama Atsushi , Ochiai Takahide , Ito Akio , Dougakiuchi Tatsuo , Edamura Tadataka , Yamanishi Masamichi
Published: June 2011

The authors report high temperature continuous-wave (cw) operations of broad-gain quantum cascade lasers based on the anticrossed dual-upper-state to multiple-lower-state design. The devices exhibit extremely wide electroluminescence (>600 cm−1) and subthreshold amplified spontaneous emission (∼570 cm−1) spectra at room temperature. Despite showing such broad electroluminescence spectra, the high-reflection coated, buried heterostructure lasers operating at 6.8 μm demonstrate a low threshold current density of ∼1.5 kA/cm2 and a high power of >500 mW with a high slope efficiency of ∼1.6 W/A in cw mode at 300 K. The maximum cw operating temperature of above 100 °C is achieved.
Tuning laser-induced band gaps in graphene
Authors: Calvo Hernán L. , Pastawski Horacio M. , Roche Stephan , Torres Luis E. F. Foa
Published: June 2011

Could a laser field lead to the much sought-after tunable band gaps in graphene? By using Floquet theory combined with Green's functions techniques, we predict that a laser field in the mid-infrared range can produce observable band gaps in the electronic structure of graphene. Furthermore, we show how they can be tuned by using the laser polarization. Our results could serve as a guidance to design optoelectronic nanodevices.
Entropy production in a mesoscopic chemical reaction system with oscillatory and excitable dynamics
Authors: Rao Ting , Xiao Tiejun , Hou Zhonghuai
Published: June 2011

Stochastic thermodynamics of chemical reaction systems has recently gained much attention. In the present paper, we consider such an issue for a system with both oscillatory and excitable dynamics, using catalytic oxidation of carbon monoxide on the surface of platinum crystal as an example. Starting from the chemical Langevin equations, we are able to calculate the stochastic entropy production P along a random trajectory in the concentration state space. Particular attention is paid to the dependence of the time-averaged entropy production P on the system size N in a parameter region close to the deterministic Hopf bifurcation (HB). In the large system size (weak noise) limit, we find that P ∼ Nβ with β = 0 or 1, when the system is below or above the HB, respectively. In the small system size (strong noise) limit, P always increases linearly with N regardless of the bifurcation parameter. More interestingly, P could even reach a maximum for some intermediate system size in a parameter region where the corresponding deterministic system shows steady state or small amplitude oscillation. The maximum value of P decreases as the system parameter approaches the so-called CANARD point where the maximum disappears. This phenomenon could be qualitatively understood by partitioning the total entropy production into the contributions of spikes and of small amplitude oscillations.
Intramolecular relaxation dynamics in semiflexible dendrimers
Authors: Kumar Amit , Biswas Parbati
Published: June 2011

The intramolecular relaxation dynamics of semiflexible dendrimers in dilute solutions are theoretically investigated in the framework of optimized Rouse-Zimm formalism. Semiflexibility is implemented by modeling topological restrictions on the bond directions and orientations of the respective bond-vectors. Based on our recently developed approach for semiflexible dendrimers [A. Kumar and P. Biswas, Macromolecules 43, 7378 (2010)], the mechanical and dielectric relaxation moduli are studied as functions of local flexibility parameters and branching topology. It is rather interesting to observe that semiflexibility affects the local modes of G′′(ω) and Δε′′(ω), which have lower relaxation rate with increasing bond restrictions, while the collective modes with small relaxation rate remain almost constant. The relaxation dynamics of the flexible dendrimer is similar to that of the semiflexible dendrimer with unrestricted bond orientations (ϕ = 0) and is flanked by the compressed (ϕ = 30°) and expanded (ϕ = 150°) conformations, respectively. The effect of semiflexibility is typically reflected in the intermediate frequency regime. The expanded conformations of semiflexible dendrimers display a power-law behavior in the intermediate frequency regime for both loss and storage modulus resembling fractal structures, while the compressed and unrestricted bond orientation conformations exhibit an approximately logarithmic dependence. The power-law exponent is found to be similar to the flexible dendrimers with excluded volume interactions. Thus, by tuning ϕ, a spectrum of dynamic relaxation pattern is obtained spanning a broad range of conformations from a power-law fractal network to a non-fractal one. In certain limits, this highly generalized model captures the characteristics of flexible dendrimers and also resembles La Ferla's model semiflexible dendrimers. The influence of hydrodynamic interactions reduces the dynamical range and the width of the intermediate domain by decreasing the smaller relaxation rates and increasing the higher relaxation rates correspondingly.
Polarization splitting in polariton electroluminescence from an organic semiconductor microcavity with metallic reflectors
Authors: Lodden Grant H. , Holmes Russell J.
Published: June 2011

Organic semiconductors have received considerable attention as the active medium in microcavity devices that exploit the regime of strong exciton–photon coupling. The eigenstates of these systems are microcavity polaritons, whose properties are an admixture of the uncoupled exciton and photon. Organic microcavities are particularly interesting due to their large exciton binding energy which permits the electrical excitation of polaritons at room temperature. Measurements of electroluminescence are often facilitated through the use of metallic reflectors that form the optical microcavity and also serve as device electrodes. Here, we demonstrate that such structures exhibit a significant polarization splitting under both optical and electrical excitation. The size of the polarization splitting rivals those observed in strongly coupled microcavities based on distributed Bragg reflectors having a long optical penetration depth.
Comparing Alternative Media in North and South: The Cases of IFIWatchnet and Indymedia in Africa
Authors: Frenzel Fabian , Böhm Steffen , Quinton Pennie , Spicer André , Sullivan Sian , Young Zoe
Published: June 2011

Alternative media form an important part of the global mediascape. Research on this phenomenon is, however, often drawn from studies in the ‘global North’. In this paper we discuss alternative media in the ‘global South’, by exploring two case studies of cooperation between Northern and Southern partners: IFIWatchnet in South America, and Indymedia Centre in Africa. We highlight how Northern and Southern partners differed in identity, organizational forms, and accountability. We find that Northern partners were oriented to more ‘marginal’ identities, fluid organizational structures, and informal structures of accountability. In contrast, Southern activists articulated more ‘mainstream’ identities, relied on more structured forms, and linked to formalized modes of accountability. The result was often significant clashes over what it meant to be alternative media, how alternative media should be organized, and how people should be held to account. This meant that North–South cooperation was often fraught with struggle. These difficulties are reminiscent of the limitations of creating global cooperation through seeking to spread modes of activist organization developed in the North, which emphasize autonomy, networks, fluidity, and, in some instances, direct action.
Performative Regional (dis)Integration: Transnational Markets, Mobile Commodities, and Bordered North–South Differences
Authors: Berndt Christian , Boeckler Marc
Published: June 2011

Being implicated in an ambivalent play of both border crossing and drawing, global commodity chains are an ideal organizational field to analyze the fundamental paradox of global connectivity. Approaching the contingency of borders from a perspective informed by the performativity approach to markets, this paper starts from the assumption that this paradox is particularly salient in the context of commodity chains which connect the Global South with the Global North. Taking the example of one single agrocommodity, the tomato, and two border regions (Morocco–EU and Mexico–USA), we follow the links and heterogeneous associations which stretch from the border to the fields, supermarket shelves, and standardization agencies to migrant labor, quality-control apparatuses, and so forth. By reading commodity chains from their literal limits, that is, from the border and from the margins, we focus on an element of this global assemblage which is normally taken for granted and excluded from academic and public discourse.
Host and viral ecology determine bat rabies seasonality and maintenance
Authors: George Dylan B. , Webb Colleen T. , Farnsworth Matthew L. , O'Shea Thomas J. , Bowen Richard A. , Smith David L. , Stanley Thomas R. , Ellison Laura E. , Rupprecht Charles E.
Published: June 2011

Rabies is an acute viral infection that is typically fatal. Most rabies modeling has focused on disease dynamics and control within terrestrial mammals (e.g., raccoons and foxes). As such, rabies in bats has been largely neglected until recently. Because bats have been implicated as natural reservoirs for several emerging zoonotic viruses, including SARS-like corona viruses, henipaviruses, and lyssaviruses, understanding how pathogens are maintained within a population becomes vital. Unfortunately, little is known about maintenance mechanisms for any pathogen in bat populations. We present a mathematical model parameterized with unique data from an extensive study of rabies in a Colorado population of big brown bats (
Eptesicus fuscus
) to elucidate general maintenance mechanisms. We propose that life history patterns of many species of temperate-zone bats, coupled with sufficiently long incubation periods, allows for rabies virus maintenance. Seasonal variability in bat mortality rates, specifically low mortality during hibernation, allows long-term bat population viability. Within viable bat populations, sufficiently long incubation periods allow enough infected individuals to enter hibernation and survive until the following year, and hence avoid an epizootic fadeout of rabies virus. We hypothesize that the slowing effects of hibernation on metabolic and viral activity maintains infected individuals and their pathogens until susceptibles from the annual birth pulse become infected and continue the cycle. This research provides a context to explore similar host ecology and viral dynamics that may explain seasonal patterns and maintenance of other bat-borne diseases.
Explaining complex codon usage patterns with selection for translational efficiency, mutation bias, and genetic drift
Authors: Shah Premal , Gilchrist Michael A.
Published: June 2011

The genetic code is redundant with most amino acids using multiple codons. In many organisms, codon usage is biased toward particular codons. Understanding the adaptive and nonadaptive forces driving the evolution of codon usage bias (CUB) has been an area of intense focus and debate in the fields of molecular and evolutionary biology. However, their relative importance in shaping genomic patterns of CUB remains unsolved. Using a nested model of protein translation and population genetics, we show that observed gene level variation of CUB in
Saccharomyces cerevisiae
can be explained almost entirely by selection for efficient ribosomal usage, genetic drift, and biased mutation. The correlation between observed codon counts within individual genes and our model predictions is 0.96. Although a variety of factors shape patterns of CUB at the level of individual sites within genes, our results suggest that selection for efficient ribosome usage is a central force in shaping codon usage at the genomic scale. In addition, our model allows direct estimation of codon-specific mutation rates and elongation times and can be readily applied to any organism with high-throughput expression datasets. More generally, we have developed a natural framework for integrating models of molecular processes to population genetics models to quantitatively estimate parameters underlying fundamental biological processes, such a protein translation.
Realization of a Knill-Laflamme-Milburn controlled-NOT photonic quantum circuit combining effective optical nonlinearities
Authors: Okamoto Ryo , O’Brien Jeremy L. , Hofmann Holger F. , Takeuchi Shigeki
Published: June 2011

Quantum information science addresses how uniquely quantum mechanical phenomena such as superposition and entanglement can enhance communication, information processing, and precision measurement. Photons are appealing for their low-noise, light-speed transmission and ease of manipulation using conventional optical components. However, the lack of highly efficient optical Kerr nonlinearities at the single photon level was a major obstacle. In a breakthrough, Knill, Laflamme, and Milburn (KLM) showed that such an efficient nonlinearity can be achieved using only linear optical elements, auxiliary photons, and measurement [Knill E, Laflamme R, Milburn GJ (2001)
Nature
409:46–52]. KLM proposed a heralded controlled-NOT (CNOT) gate for scalable quantum computation using a photonic quantum circuit to combine two such nonlinear elements. Here we experimentally demonstrate a KLM CNOT gate. We developed a stable architecture to realize the required four-photon network of nested multiple interferometers based on a displaced-Sagnac interferometer and several partially polarizing beamsplitters. This result confirms the first step in the original KLM “recipe” for all-optical quantum computation, and should be useful for on-demand entanglement generation and purification. Optical quantum circuits combining giant optical nonlinearities may find wide applications in quantum information processing, communication, and sensing.
Domain expertise insulates against judgment bias by monetary favors through a modulation of ventromedial prefrontal cortex
Authors: Kirk Ulrich , Harvey Ann , Montague P. Read
Published: June 2011

Recent work using an art-viewing paradigm shows that monetary sponsorship of the experiment by a company (a favor) increases the valuation of paintings placed next to the sponsoring corporate logo, an effect that correlates with modulation of the ventromedial prefrontal cortex (VMPFC). We used the same art-viewing paradigm to test a prevailing idea in the domain of conflict-of-interest: that expertise in a domain insulates against judgment bias even in the presence of a monetary favor. Using a cohort of art experts, we show that monetary favors do not bias the experts’ valuation of art, an effect that correlates with a lack of modulation of the VMPFC across sponsorship conditions. The lack of sponsorship effect in the VMPFC suggests the hypothesis that their brains remove the behavioral sponsorship effect by censoring sponsorship-dependent modulation of VMPFC activity. We tested the hypothesis that prefrontal regions play a regulatory role in mediating the sponsorship effect. We show that the dorsolateral prefrontal cortex (DLPFC) is recruited in the expert group. Furthermore, we tested the hypothesis in nonexpert controls by contrasting brain responses in controls who did not show a sponsorship effect to controls who did. Changes in effective connectivity between the DLPFC and VMPFC were greater in nonexpert controls, with an absence of the sponsorship effect relative to those with a presence of the sponsorship effect. The role of the DLPFC in cognitive control and emotion regulation suggests that it removes the influence of a monetary favor by controlling responses in known valuation regions of the brain including the the VMPFC.
Artificial selection for a green revolution gene during
japonica
rice domestication
Authors: Asano Kenji , Yamasaki Masanori , Takuno Shohei , Miura Kotaro , Katagiri Satoshi , Ito Tomoko , Doi Kazuyuki , Wu Jianzhong , Ebana Kaworu , Matsumoto Takashi , Innan Hideki , Kitano Hidemi , Ashikari Motoyuki , Matsuoka Makoto
Published: June 2011

The semidwarf phenotype has been extensively selected during modern crop breeding as an agronomically important trait. Introduction of the semidwarf gene,
semi
-
dwarf1
(
sd1
), which encodes a gibberellin biosynthesis enzyme, made significant contributions to the “green revolution” in rice (
Oryza sativa
L.). Here we report that
SD1
was involved not only in modern breeding including the green revolution, but also in early steps of rice domestication. We identified two SNPs in
O. sativa
subspecies (ssp.)
japonica SD1
as functional nucleotide polymorphisms (FNPs) responsible for shorter culm length and low gibberellin biosynthetic activity. Genetic diversity analysis among
O. sativa
ssp.
japonica
and
indica
, along with their wild ancestor
O. rufipogon
Griff, revealed that these FNPs clearly differentiate the
japonica
landrace and
O. rufipogon
. We also found a dramatic reduction in nucleotide diversity around
SD1
only in the
japonica
landrace, not in the
indica
landrace or
O. rufipogon
. These findings indicate that
SD1
has been subjected to artificial selection in rice evolution and that the FNPs participated in
japonica
domestication, suggesting that ancient humans already used the green revolution gene.
Hund’s rule in superatoms with transition metal impurities
Authors: Medel Victor M. , Reveles Jose Ulises , Khanna Shiv N. , Chauhan Vikas , Sen Prasenjit , Castleman A. Welford
Published: June 2011

The quantum states in metal clusters bunch into supershells with associated orbitals having shapes resembling those in atoms, giving rise to the concept that selected clusters could mimic the characteristics of atoms and be classified as superatoms. Unlike atoms, the superatom orbitals span over multiple atoms and the filling of orbitals does not usually exhibit Hund’s rule seen in atoms. Here, we demonstrate the possibility of enhancing exchange splitting in superatom shells via a composite cluster of a central transition metal and surrounding nearly free electron metal atoms. The transition metal d states hybridize with superatom D states and result in enhanced splitting between the majority and minority sets where the moment and the splitting can be controlled by the nature of the central atom. We demonstrate these findings through studies on TMMg

n

clusters where TM is a 3d atom. The clusters exhibit Hund’s filling, opening the pathway to superatoms with magnetic shells.