bluuebunny/crossref_metadata_2025 huggingface dataset:
Length–weight relationship, age, growth and mortality of Atlantic chub mackerel Scomber colias in the Adriatic Sea
Authors: Čikeš Keč Vanja , Zorica Barbara
Published: April 2012

Chub mackerel, Scomber colias, is widely distributed in the warm waters of the Atlantic Ocean including the Mediterranean and Adriatic Seas. This medium-sized pelagic fish species occurs in deeper waters during the colder part of the year and schools are found in coastal waters during the warmer parts of the year, where they spawn and feed. Atlantic chub mackerel is one of the most important commercial fish throughout its habitat and as a consequence of its wide distribution and broad commercial exploitation, biological information on the growth and mortality is required for stock assessment and management. Despite the abundance and economic importance of S. colias in the Adriatic Sea, knowledge about its biology and population dynamics is still limited. Studies of the age, growth, mortality and exploitation rates of S. colias have not been undertaken previously in the Adriatic Sea. Therefore, the exploitation status of this species' stock in the Adriatic Sea is unknown. The purpose of this study was to provide information on the age, growth and length–weight relationship as well as estimates of mortality and exploitation rate in order to define the present state of the population in the Adriatic Sea.
Long term trends in population dynamics and reproduction inHolothuria atra(Aspidochirotida) in the southern Great Barrier Reef; the importance of asexual and sexual reproduction
Authors: Thorne Benjamin V. , Eriksson Hampus , Byrne Maria
Published: April 2012

Population density and the presence of fission products ofHolothuria (Halodeima) atrawere investigated in surveys taken over 5 years (2006–2010) in the Capricorn Bunker Group, Southern Great Barrier Reef. These surveys were undertaken to document population density over time and assess the potential that asexual reproduction contributes to population maintenance. Over the 5 years a low incidence of fission was evident year-round, with an increase in July and August (13 and 27% of the population, respectively). There was a positive correlation between population density and the presence of fission products across all surveys. Although density fluctuated, there was no significant difference between months or sites. Despite the potential increase that might be expected from fission followed by regeneration, density fluctuated around a mean of 0.77 ind. m−2. Examination of gonads of the small (asexual and sexual reproduction) and large (sexual only) morphs ofH. atraindicated a difference in reproductive pattern. Many small morphs lacked gonads during winter and, when they developed gonads, the gonad index (GI) was low. The GI pattern of the small morph indicated that they spawned in summer. In comparison the large morph had conspicuous gonads through the year. The GI of the large morph was high in winter and summer indicating greater, more prolonged spawning activity in these individuals.
Informed Citizens? Knowledge of Rights and the Resolution of Civil Justice Problems
Authors: DENVIR CATRINA , BALMER NIGEL J. , BUCK ALEXY
Published: April 2012

Previous studies have highlighted the paucity of knowledge possessed by people in a number of jurisdictions with regard to specific legal issues and processes, yet what has not been fully understood is the practical impact of this lack of knowledge. This paper looks at how knowledge of rights affects the resolution of civil justice problems. Data were extracted from a large-scale survey of adults’ experience of rights problems throughout England and Wales (10,537 adult respondents). The results demonstrated that most individuals were not aware of their rights at the time the problem occurred (64.8 per cent). Knowledge was shown to be poorest amongst those with mental illness, those without higher qualifications and those renting their homes. Problems where knowledge was poor included clinical negligence, welfare benefits and neighbours issues. Knowledge did not appear to be related to a particular problem-solving strategy but had an impact on the fulfilment of objectives and the obtaining of advice. Our findings depart from existing literature by indicating that knowledge of rights alone is not associated with legal self-sufficiency in terms of a reduced dependence upon legal advice services. We find, however, that individuals, with knowledge of rights, experience better outcomes when they opt to handle their problem alone. Accordingly, the presence or absence of knowledge of rights may be a useful proxy measure of legal advice need and relevant to the process of legal aid rationing. Our findings highlight the role that Public Legal Education (PLE) (both ‘rights-based education’ and ‘just-in-time/self-help’) may play in disposing of less complex problems, while presenting a strong case for the continued availability of free legal advice services. The research is discussed in the context of the recently announced legal aid reforms in England and Wales and their anticipated impact.
X-ray powder diffraction analysis of a new magnesium chromate hydrate, MgCrO4·11H2O
Authors: Fortes A. Dominic , Wood Ian G.
Published: April 2012

A new hydrate of magnesium chromate is synthesized by quenching aqueous solutions of MgCrO4 in liquid nitrogen. MgCrO4·11H2O is isostructural with the rare mineral meridianiite (MgSO4·11H2O) being triclinic, $P{\bar 1}$, Z = 2, with unit-cell parameters a = 6.811 33(8) Å, b = 6.958 39(9) Å, c = 17.3850(2) Å, α = 87.920(1)°, β = 89.480(1)°, γ = 62.772(1)°, and V = 732.17(1) Å3 at −15 °C. The difference in unit-cell parameters between SO4- and CrO4-bearing species is only partially accounted for by the difference in S–O and Cr–O bond lengths; the remainder of the difference (over 90% in the cell volume) is attributed to weakening of the interpolyhedral hydrogen-bond network.
Synthesis and recycling of antifreeze glycoproteins in polar fishes
Authors: Evans Clive W. , Hellman Linn , Middleditch Martin , Wojnar Joanna M. , Brimble Margaret A. , Devries Arthur L.
Published: April 2012

Evolutionary disparate Antarctic notothenioids and Arctic gadids have adapted to their freezing environments through the elaboration of essentially identical antifreeze glycoproteins (AFGPs). Here we show that this convergence of molecular identity, which evolved from unrelated parent genes, extends to convergence in physiological deployment. Both fish groups synthesize AFGPs in the exocrine pancreas from where they are discharged into the gut to inhibit the growth of ingested ice. Antifreeze glycoproteins not lost with the faeces are resorbed from the gut via the rectal epithelium, transported to the blood and ultimately secreted into the bile, from where they re-enter the gastrointestinal tract. Antifreeze glycoprotein recirculation conserves energy expenditure and explains how high levels of AFGPs reach the blood in notothenioids since, unlike Arctic gadids which also synthesize AFGP in the liver, AFGP secretion in notothenioids is directed exclusively towards the gastrointestinal lumen. Since AFGPs function by inhibiting ice crystal growth, ice must be present for them to function. The two fish groups are thus faced with an identical problem of how to deal with internal ice. Here we show that both accumulate AFGPs within ellipsoidal macrophages of the spleen, presumably adsorbed to phagocytosed ice crystals which are then held until a warming event ensues.
A Qualitative and Quantitative Study of the Surgical and Rehabilitation Response to the Earthquake in Haiti, January 2010
Authors: Redmond Anthony D. , Mardel Simon , Taithe Bertrand , Calvot Thomas , Gosney Jim , Duttine Antony , Girois Susan
Published: April 2012

Background: The disaster response environment in Haiti following the 2010 earthquake represented a complex healthcare challenge. This study was designed to identify challenges during the Haiti disaster response.

Methods: Qualitative and quantitative study of injured patients carried out six months after the January 2010 earthquake in Haiti to review the surgical inputs of foreign medical teams.

Results: Study findings revealed a need during the response for improved medical records and data gathering for regulation, quality assurance, coordination and resource allocation; wider adherence to standard patient referral mechanisms and protocols linking surgical service provision with appropriate hospital and community based rehabilitation services; a greater recognition of the impact of non-amputation injury, and the need for patients to have a greater say in their management and to be the keepers of their medical records. Key first steps to improving the international response are a minimum dataset and uniform reporting.

Conclusion: This study showed that challenges for emergency medical response during the Haiti Earthquake involved issues of accountability, professional ethics, standards-of-care, unmet needs, patient agency and expected outcomes for patients in such settings:
Observing system simulation experiments of dissolved oxygen monitoring in Massachusetts Bay
Authors: Xue Pengfei , Chen Changsheng , Beardsley Robert C.
Published: April 2012

Observing system simulation experiments (OSSEs) were performed in Massachusetts Bay for the design of optimal monitoring sites for dissolved oxygen (DO) measurements. Experiments were carried out using the Ensemble Kalman Filter (EnKF) for data assimilation with focus on initial and boundary perturbations. Running a well‐validated water quality model with a perturbed initial field of DO but “true” boundary forcing conditions, the model is capable of restoring DO back to the true state without data assimilation over a recovery time scale of about a month. Since DO in Massachusetts Bay has a bay‐wide correlation scale, placing a monitoring site of DO near the northern boundary or at a location that has maximum correlation to the entire domain can shorten the restoring time to a week. Running the model with perturbed boundary forcing without data assimilation, the results show that the errors propagate into Massachusetts Bay following the inflow from the northern boundary and spread southward to Cape Cod Bay over a time scale of about a month. Using a DO monitoring site located near the northern entrance, the data assimilation can efficiently control the error propagation and prevent the model field from deviating from the true state. The model shows that the inflow from the northern entrance, which is connected to the upstream Western Maine Coastal Current, plays an important role in controlling the DO variation in Massachusetts Bay, and the residence time of the bay controlled by this flow is about one month. Understanding the upstream boundary‐control nature of this system is critical for optimal design of sampling strategies of water quality variables in this region.
Strike‐slip tectonics and Quaternary basin formation along the Vienna Basin fault system inferred from Bouguer gravity derivatives
Authors: Salcher B. C. , Meurers B. , Decker K. , Hölzel M. , Wagreich M.
Published: April 2012

The Vienna Basin at the transition between the Alpine and Carpathian belt hosts a number of large Pleistocene sub‐basins forming along an active continental scale strike‐slip fault (Vienna Basin strike‐slip fault). We utilize first‐order derivatives from industrial Bouguer gravity data to unravel the impacts of Pleistocene kinematics on the Vienna Basin and to compensate for the lack of near‐surface fault data. Anomalies have been evaluated by independent geophysical and geological data and were integrated to build up a tectonic model. Factors influencing the wavelength and the amplitude of anomalies were additionally investigated by 2‐D models to better interpret field data. Subsidence and related accumulation of Quaternary sediments in the Vienna Basin produce significant gravity signals related to the activity of the strike‐slip fault. The constrained fault patterns and structures highlight tight and elongated transtensional pull‐apart basins with typically associated features like separated depocenters and Riedel fractured sidewalls in an en‐echelon alignment. Further Pleistocene basins are highlighted as tectonic grabens developing along branches of the master fault. The Vienna Basin is additionally affected by minor deformation represented by both subsidence along major Miocene sidewalls and NW‐SE faulting resulting in distinct topographic features, which manifests kinematics on a regional scale. The clear density contrasts between Miocene marine and Quaternary terrestrial sediments, as well as the exceptional database, provide a unique framework to demonstrate advantages of incorporating gravity derivatives for near‐surface fault analysis.
Efficient methods for large‐scale linear inversion using a geostatistical approach
Authors: Saibaba Arvind K. , Kitanidis Peter K.
Published: April 2012

In geophysical inverse problems, such as estimating the unknown parameter field from noisy observations of dependent quantities, e.g., hydraulic conductivity from head observations, stochastic Bayesian and geostatistical approaches are frequently used. To obtain best estimates and conditional realizations it is required to perform several matrix‐matrix computations involving the covariance matrix of the discretized field of the parameters. In realistic three‐dimensional fields that are finely discretized, these operations as performed in conventional algorithms become extremely expensive and even prohibitive in terms of memory and computational requirements. Using Hierarchical Matrices, we show how to reduce the complexity of forming approximate matrix‐vector products involving the Covariance matrices in log linear complexity for an arbitrary distribution of points and a wide variety of generalized covariance functions. The resulting system of equations is solved iteratively using a matrix‐free Krylov subspace approach. Furthermore, we show how to generate unconditional realizations using an approximation to the square root of the covariance matrix using Chebyshev matrix polynomials and use the above to generate conditional realizations. We demonstrate the efficiency of our method on a few standard test problems, such as interpolation from noisy observations and contaminant source identification.
Bevacizumab-induced tumor calcifications can be elicited in glioblastoma microspheroid culture and represent massive calcium accumulation death (MCAD) of tumor endothelial cells
Authors: Weiseenthal Larry , Williamson Summer , Brunschwiler Cindy , Rueff-Weisenthal Constance
Published: April 2012

Bähr and colleagues reported that 22 of 36 glioblastoma patients treated with bevacizumab showed tumor calcifications on 8 week post therapy follow up with MRI. Early tumor calcification strongly predicted for response, time to progression, and overall survival. The authors didn’t understand the mechanism, but speculated that it was vascular in nature. At the 13th International Anti-Angiogenic Symposium (2011), we presented our discovery of the phenomenon of massive calcium accumulation death, wherein MCAD occurred in endothelial cells (tumor, circulating, and HUVEC), in response to VEGF depletion by bevacizumab and other putative anti-angiogenic agents, but not in response to non-specific cytotoxins. In subsequent work, we have documented marked MCAD to occur in primary microcluster cultures from 6 fresh human glioblastoma biopsies, following 96 hours of VEGF depletion in vitro by bevacizumab. The presence and degree of MCAD is strikingly dependent on the type of serum in the culture medium (RPMI-1640 + 25% serum) -- typically most striking in (very low VEGF) fetal calf serum, but inhibited (often) or enhanced (rarely) by 25% human serum from different patients or normal donors containing variable quantities of VEGF. There was not a linear relationship between VEGF concentration and MCAD inhibition (or enhancement), suggesting that other pro-angiogenic (or anti-angiogenic) serum factors may play a role. In epithelial metastatic tumors, circulating peripheral blood endothelial cells may be easily tested, using our methods, and the serum inhibition (or, rarely, enhancement) is faithfully reproduced on circulating endothelial cells, in comparison with the tumor cluster-associated endothelial cells. We propose MCAD as the mechanism of glioblastoma calcification following bevacizumab and further propose that testing tumor microclusters and/or circulating endothelial cells, in the presence of autologous serum, could be a useful predictive biomarker and research tool.
Comment on “Debye shielding in a nonextensive plasma” [Phys. Plasmas 18, 062102 (2011)]
Authors: Rios L. A. , Galvão R. M. O. , Cirto L.
Published: April 2012

Gougam and Tribeche [Phys. Plasmas 18, 062102 (2011)] revisit the phenomenon of Debye shielding within the theoretical framework of Tsallis statistical mechanics. The effect of electron nonextensivity on the Bohm sheath criterion is also investigated, and a modified critical Mach number is derived. However, their results are questionable, since they are based on a somewhat unjustified assumption about the parameter that specifies the width of the distribution function.
Low-cost shrink lithography with sub-22 nm resolution
Authors: Zhang Bo , Zhang Min , Cui Tianhong
Published: April 2012

A low-cost shrink lithogragphy technique with 21 nm resolution is presented in this paper. The shrink lithography uses embossing approach to pattern the heat-shrink polymer film, and thermally shrink the film as a shadow mask subsequently. Metal patterns with diffferent feature sizes were achieved from a single mold by shrink lithography through controlling the shrink contidions including temperature and force. A biosensor based on a suspended graphene nanoribbon is fabricated with the shrink lithography, demonstrating the potential application of this process to the fabrication of nanodevices and integrated circuits.
On the origin of an additional Raman mode at 275 cm−1 in N-doped ZnO thin films
Authors: Wu Keyue , Fang Qingqing , Wang Weina , Thomas M. Allan , Cui Jingbiao
Published: April 2012

A systematic investigation on the optical properties of N-doped ZnO thin films was performed in order to understand the origin of an additional Raman mode at 275 cm−1. This Raman peak was observable only at N2 pressures lower than 30 Pa during pulsed laser deposition. Its intensity decreased with an increase of N2 pressures and eventually vanished at pressures above 30 Pa. N substitution of O (NO) was identified by photoluminescence and x-ray photoelectron spectroscopy and correlated well with the Raman intensity. The electrical measurements showed significant changes in resistivity, charge carrier concentration, and mobility due to the presence of N acceptors. Investigations on undoped ZnO films grown in Ar without N2 further confirm that N doping plays a key role in the Raman scattering. The experimental data indicate that the Raman mode originates from NO related complexes, likely in the form of Zni-NO. These investigations help to understand the doping mechanisms and underlying physics of the additional Raman mode in the ZnO films.
Stagnation of a gas puff Z pinch
Authors: Strauss H. R.
Published: April 2012

Simulations of a gas puff Z pinch were performed, using an appropriately modified version of the M3D code [Park et al., Phys. Plasmas 6, 1796 (1999)]. The simulations investigated the stagnation process, including the effects of the shock driven by the magnetic piston and the influence of the Rayleigh Taylor instability. The results compare favorably with recent experimental measurements. The stagnated plasma reaches a quasi equilibrium with approximate balance of plasma pressure and magnetic pressure, measured by β≤1. The dependence of the stagnation radius on β and radiative energy loss are calculated, using a simple radiation model.
Theory of volume transition in polyelectrolyte gels with charge regularization
Authors: Hua Jing , Mitra Mithun K. , Muthukumar M.
Published: April 2012

We present a theory for polyelectrolyte gels that allow the effective charge of the polymer backbone to self-regulate. Using a variational approach, we obtain an expression for the free energy of gels that accounts for the gel elasticity, free energy of mixing, counterion adsorption, local dielectric constant, electrostatic interaction among polymer segments, electrolyte ion correlations, and self-consistent charge regularization on the polymer strands. This free energy is then minimized to predict the behavior of the system as characterized by the gel volume fraction as a function of external variables such as temperature and salt concentration. We present results for the volume transition of polyelectrolyte gels in salt-free solvents, solvents with monovalent salts, and solvents with divalent salts. The results of our theoretical analysis capture the essential features of existing experimental results and also provide predictions for further experimentation. Our analysis highlights the importance of the self-regularization of the effective charge for the volume transition of gels in particular, and for charged polymer systems in general. Our analysis also enables us to identify the dominant free energy contributions for charged polymer networks and provides a framework for further investigation of specific experimental systems.
Ultrafast laser-induced changes in optical properties of semiconductors
Authors: Chirila C. C. , Lim Freda C. H. , Gavaza M. G.
Published: April 2012

We study the effect of laser radiation on optical properties of semiconductors of industrial interest. The material is pumped with a laser of chosen central frequency, for which the absorption is maximal, thus inducing electron dynamics, which modifies the optical properties. By using an improved theoretical model, we study ultrafast dynamic changes in the refraction index and reflectivity corresponding to a wide frequency-interval of probing radiation and identify that interval where these optical changes are most significant.
Semiconducting behavior of niobium-doped titanium oxide in the amorphous state
Authors: Ok Kyung-Chul , Park Joseph , Ho Lee Ju , Du Ahn Byung , Hun Lee Je , Chung Kwun-Bum , Park Jin-Seong
Published: April 2012

Electrical properties of Nb-doped titanium oxide films were evaluated with respect to annealing temperatures. Although an amorphous phase is preserved up to 450 °C, x-ray absorption spectroscopy analyses indicate that crystal field splitting in the conduction band begins to take place at this temperature. Such molecular orbital ordering effects induce a semiconducting behavior, which is manifested by working thin film transistor devices with field effect mobility values as high as 0.64 cm2/Vs. X-ray photoelectron spectroscopy studies disclose a drastic increase in Nb+5 states upon heat treatment, and these may be attributed to oxygen deficient states that generate free electrons.
Origin of size-dependent photoluminescence decay dynamics in colloidal γ-Ga2O3 nanocrystals
Authors: Hegde Manu , Wang Ting , Miskovic Zoran L. , Radovanovic Pavle V.
Published: April 2012

We studied size-dependent dynamics of defect-based photoluminescence of colloidal γ-Ga2O3 nanocrystals in the framework of the donor-acceptor pair model. Two theoretical models were developed based on relative positioning of donor and acceptor sites: (1) for random distribution of defects throughout the nanocrystal volume and (2) for surface segregation of defects. The results of the modeling indicate that defect sites are predominantly located in the vicinity of nanocrystal surfaces and that the density of defects increases with decreasing nanocrystal size. The donor Bohr radius obtained as a fitting parameter suggests an increase in the donor binding energy with decreasing nanocrystal size.
Band structures of exchange spin waves in one-dimensional bi-component magnonic crystals
Authors: Ma F. S. , Lim H. S. , Zhang V. L. , Wang Z. K. , Piramanayagam S. N. , Ng S. C. , Kuok M. H.
Published: April 2012

We present the micromagnetic study of magnonic band structures for exchange spin waves propagating in one-dimensional magnonic crystals. The crystals are of laterally patterned periodic arrays of alternating cobalt and nickel stripes. Large magnonic bandgaps with widths of tens of GHz are observed. It is found that the higher-order transmission bands and bandgaps have wider widths than those of the lower-order bands and bandgaps. Another interesting feature is that the widths of the first two bandgaps are independent of the applied field, in contrast with an earlier report of decreasing bandgap widths with increasing applied field observed for dipolar spin waves.
Influence of La and Mn dopants on the current-voltage characteristics of BiFeO3/ZnO heterojunction
Authors: Xu Jianlong , Jia Ze , Zhang Naiwen , Ren Tianling
Published: April 2012

We report the influence of La and Mn dopants on the current-voltage characteristics of BiFeO3/ZnO heterojunction. The increased current densities (J) and enhanced diodelike behavior are clearly observed in (Bi0.95La0.05)FeO3/ZnO and Bi(Fe0.95Mn0.05)O3/ZnO compared to BiFeO3/ZnO. The diodelike behavior is found to arise from the polarization switching of the ferroelectric layer and the resulting interfacial charge distribution. A ferroelectric-semiconductor (FS) model is proposed to understand the physics origins of the La and Mn dopants induced current density and diodelike behavior enhancement. Further studies into the conduction mechanisms reveal that the dominant conduction mechanisms in low electric fields vary with La and Mn dopants, while they remain the same in high electric fields.
Impact of active layer design on InGaN radiative recombination coefficient and LED performance
Authors: Li X. , Okur S. , Zhang F. , Avrutin V. , Özgür Ü. , Morkoç H. , Hong S. M. , Yen S. H. , Hsu T. C. , Matulionis A.
Published: April 2012

The relative roles of radiative and nonradiative processes and the polarization field on the light emission from blue (∼425 nm) InGaN light emitting diodes (LEDs) have been studied. Single and multiple double heterostructure (DH) designs have been investigated with multiple DH structures showing improved efficiencies. Experimental results supported by numerical simulations of injection dependent electron and hole wavefunction overlap and the corresponding radiative recombination coefficients suggest that increasing the effective active region thickness by employing multiple InGaN DH structures separated by thin and low barriers is promising for LEDs with high efficiency retention at high injection. The use of thin and low barriers is crucial to enhance carrier transport across the active region. Although increasing the single DH thickness from 3 to 6 nm improves the peak external quantum efficiency (EQE) by nearly 3.6 times due to increased density of states and increased emitting volume, the internal quantum efficiency (IQE) suffers a loss of nearly 30%. A further increase in the DH thickness to 9 and 11 nm results in a significantly slower rate of increase of EQE with current injection and lower peak EQE values presumably due to degradation of the InGaN material quality and reduced electron-hole spatial overlap. Increasing the number of 3 nm DH active regions separated by thin (3 nm) In0.06Ga0.94N barriers improves EQE, while maintaining high IQE (above 95% at a carrier concentration of 1018 cm−3) and showing negligible EQE degradation up to 550 A/cm2 in 400 × 400 μm2 devices due to increased emitting volume and high radiative recombination coefficients and high IQE. Time-resolved photoluminescence measurements revealed higher radiative recombination rates with increasing excitation due to screening of the internal field and enhanced electron and hole overlap at higher injection levels. To shed light on the experimental observations, the effect of free-carrier screening on the polarization field at different injection levels and the resulting impact on the quantum efficiency were investigated by numerical simulations.
Design of ductile bulk metallic glasses by adding “soft” atoms
Authors: Zheng N. , Qu R. T. , Pauly S. , Calin M. , Gemming T. , Zhang Z. F. , Eckert J.
Published: April 2012

We propose a strategy for the design of ductile bulk metallic glasses (BMGs) through minor substitution using relatively large atoms, which make the bonding nature become more metallic and with it less shear resistant. Such a locally modified structure results in topological heterogeneity, which appears to be crucial for achieving enhanced plasticity. This strategy is verified for Ti-Zr-Cu-Pd glassy alloys, in which Cu was replaced by In, and seems to be extendable to other BMG systems. The atomic-scale heterogeneity in BMGs is somewhat analog to defects in crystalline alloys and helps to improve the overall plasticity of BMGs.
Advantages of GaN based light-emitting diodes with a p-InGaN hole reservoir layer
Authors: Lu Taiping , Li Shuti , Liu Chao , Zhang Kang , Xu Yiqin , Tong Jinhui , Wu Lejuan , Wang Hailong , Yang Xiaodong , Yin Yian , Xiao Guowei , Zhou Yugang
Published: April 2012

A p-type InGaN hole reservoir layer (HRL) was designed and incorporated in GaN based light-emitting diodes (LEDs) to enhance hole injection efficiency and alleviate efficiency droop. The fabricated LEDs with p-type HRL exhibited higher light output power, smaller emission energy shift and broadening as compared to its counterpart. Based on electrical and optical characteristics analysis and numerical simulation, these improvements are mainly attributed to the alleviated band bending in the last couple of quantum well and electron blocking layer, and thus better hole injection efficiency. Meanwhile, the efficiency droop can be effectively mitigated when the p-InGaN HRL was used.
Tuning minority-carrier lifetime through stacking fault defects: The case of polytypic SiC
Authors: Chen Bin , Matsuhata Hirofumi , Sekiguchi Takashi , Kinoshita Akimasa , Ichinoseki Kyouichi , Okumura Hajime
Published: April 2012

Minority-carrier lifetime is one of the key parameters governing the performance of semiconductor devices. Here, we report on tuning the minority-carrier lifetime through stacking fault (SF) defects in polytypic SiC. The SFs are distinguished in terms of their characteristic luminescence peaks at 482 nm, 471 nm, and 417 nm, respectively. Different from general point, linear, and volume defects, the planar SFs demonstrate the interesting phenomena of either decreasing or increasing the minority-carrier lifetime, which depend on the SF-related energy levels. The mechanism for the down/up modulation of the carrier lifetime through the SFs is discussed.
Short- and long-term movement patterns in the freshwater whipray (Himantura dalyensis) determined by the signal processing of passive acoustic telemetry data
Authors: Campbell Hamish A. , Hewitt Matthew , Watts Matthew E. , Peverell Stirling , Franklin Craig E.
Published: April 2012

Patterns of movement in aquatic animals reflect ecologically important behaviours. Cyclical changes in the abiotic environment influence these movements, but when multiple processes occur simultaneously, identifying which is responsible for the observed movement can be complex. Here we used acoustic telemetry and signal processing to define the abiotic processes responsible for movement patterns in freshwater whiprays (Himantura dalyensis). Acoustic transmitters were implanted into the whiprays and their movements detected over 12 months by an array of passive acoustic receivers, deployed throughout 64 km of the Wenlock River, Qld, Australia. The time of an individual’s arrival and departure from each receiver detection field was used to estimate whipray location continuously throughout the study. This created a linear-movement-waveform for each whipray and signal processing revealed periodic components within the waveform. Correlation of movement periodograms with those from abiotic processes categorically illustrated that the diel cycle dominated the pattern of whipray movement during the wet season, whereas tidal and lunar cycles dominated during the dry season. The study methodology represents a valuable tool for objectively defining the relationship between abiotic processes and the movement patterns of free-ranging aquatic animals and is particularly expedient when periods of no detection exist within the animal location data.
Mutations that stabilize the open state of the
Erwinia chrisanthemi
ligand-gated ion channel fail to change the conformation of the pore domain in crystals
Authors: Gonzalez-Gutierrez Giovanni , Lukk Tiit , Agarwal Vinayak , Papke David , Nair Satish K. , Grosman Claudio
Published: April 2012

The determination of structural models of the various stable states of an ion channel is a key step toward the characterization of its conformational dynamics. In the case of nicotinic-type receptors, different structures have been solved but, thus far, these different models have been obtained from different members of the superfamily. In the case of the bacterial member ELIC, a cysteamine-gated channel from
Erwinia chrisanthemi
, a structural model of the protein in the absence of activating ligand (and thus, conceivably corresponding to the closed state of this channel) has been previously generated. In this article, electrophysiological characterization of ELIC mutants allowed us to identify pore mutations that slow down the time course of desensitization to the extent that the channel seems not to desensitize at all for the duration of the agonist applications (>20 min). Thus, it seems reasonable to conclude that the probability of ELIC occupying the closed state is much lower for the ligand-bound mutants than for the unliganded wild-type channel. To gain insight into the conformation adopted by ELIC under these conditions, we solved the crystal structures of two of these mutants in the presence of a concentration of cysteamine that elicits an intracluster open probability of >0.9. Curiously, the obtained structural models turned out to be nearly indistinguishable from the model of the wild-type channel in the absence of bound agonist. Overall, our findings bring to light the limited power of functional studies in intact membranes when it comes to inferring the functional state of a channel in a crystal, at least in the case of the nicotinic-receptor superfamily.
Ewald Weibel: An organelle of his very own, and more
Authors: Sedwick Caitlin
Published: April 2012

Weibel built his career using electron microscopy to study cells, tissues, and biological systems.
Une madeleine peut en cacher une autre: un dialogue mythique sur le Temps entre Marcel Proust, Alfred Hitchcock et Chris Marker
Authors: Picherit Hervé
Published: April 2012

La Jetée
et
Immemory
, œuvres de Chris Marker, réalisent un lien des plus inattendus entre
À la recherche du temps perdu
de Marcel Proust et
Vertigo
d'Alfred Hitchcock. En nous interrogeant sur la nature des ‘Madeleines’ se trouvant dans ces deux œuvres,
Immemory
indique l'enjeu du raccord qu'opère
La Jetée
. Car l'œuvre hitchcockienne, comme la proustienne, recèle une philosophie unique du souvenir. Tandis que
Vertigo
présente une Madeleine qui, agissant sur les structures du temps, tente d'attirer et Scottie et le spectateur dans son infinité néfaste, la
Recherche
met en scène une madeleine menant, certes, au temps retrouvé, mais aussi au-delà des pièges d'une souvenance trop servile à elle-même. Le lien que permet
La Jetée
assure tout d'abord l'enrichissement mutuel des univers proustien et hitchcockien, mais il ne constitue ni une synthèse de ces philosophies, ni une quelconque définition du concept de la ‘Madeleine’. Marker établit, au contraire, un dialogue transtextuel qui, d'après les critères d'Émile Durkheim, de Claude Lévi-Strauss et de Friedrich Wilhelm Schelling, participe de la création mythologique. Grâce à l'influence de
La Jetée
et d'
Immemory
, la ‘Madeleine’ serait donc devenue un élément mythique qui, tout en étant né des œuvres proustienne et hitchcockienne, est indépendant d'elles.
Modelling river history and evolution
Authors: Coulthard T. J. , Van De Wiel M. J.
Published: April 2012

Over the last few decades, a suite of numerical models has been developed for studying river history and evolution that is almost as diverse as the subject of river history itself. A distinction can be made between landscape evolution models (LEMs), alluvial architecture models, meander models, cellular models and computational fluid dynamics models. Although these models share some similarities, there also are notable differences between them, which make them more or less suitable for simulating particular aspects of river history and evolution. LEMs embrace entire drainage basins at the price of detail; alluvial architecture models simulate sedimentary facies but oversimplify flow characteristics; and computational fluid dynamics models have to assume a fixed channel form. While all these models have helped us to predict erosion and depositional processes as well as fluvial landscape evolution, some areas of prediction are likely to remain limited and short-term owing to the often nonlinear response of fluvial systems. Nevertheless, progress in model algorithms, computing and field data capture will lead to greater integration between these approaches and thus the ability to interpret river history more comprehensively.
Historical sources and watershed evolution
Authors: Trimble Stanley W.
Published: April 2012

Historical data, including structures, documents, photographs and eyewitness reports, allow changes in some drainage basins to be documented in fine detail over time periods ranging from a few days to several decades. The USA is rich in data sources that are freely available. Rates of bank erosion, meander migration, channel width, riparian vegetation and watershed land use and cover conditions can be assessed, which are especially valuable where there is controversy over the human contribution to erosion and deposition. Studies of Coon Creek and the southern Piedmont of the USA have yielded results that sometimes contradict established views.
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Pb geochronology of flood events in large tropical river systems
Authors: Aalto Rolf , Nittrouer Charles A.
Published: April 2012

Floodplain sedimentation removes particles from fluvial transport and constructs stratigraphic records of flooding, biogeochemical sequestration and other aspects of the environmental history of river basins—insight that is enhanced by accurate geochronology. The natural fallout radionuclide
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Pb, often employed to date lacustrine and marine sediments, has previously been used to determine floodplain accumulation rates over decadal-to-century time scales using the assumption that both input concentration and sediment accumulation rates are constant. We test this model in approximately 110 cores of pristine floodplains along approximately 2000 km of the Rios Beni and Mamore in northern Bolivia; over 95 per cent of the
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Pb profiles depict individual episodic deposition events, not steady-state accumulation, requiring a revised geochronological methodology. Discrete measurements of down-core, clay-normalized adsorbed excess
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Pb activity are coupled with a new conceptual model of
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Pb input during floods: constant initial reach clay activity, unknown sedimentation (CIRCAUS). This enhanced methodology yields
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Pb dates that correspond well with (i) dates determined from meteoric caps, (ii) observed dates of river bar formation, (iii) known flood dates, and (iv) dates from nearby cores along the same transect. Similar results have been found for other large rivers. The CIRCAUS method for geochronology therefore offers a flexible and accurate method for dating both episodic (decadal recurrence frequency) and constant (annual recurrence) sediment accumulation on floodplains.
Polylysine Copolymers for Gene Delivery
Authors: Kim Sung Wan
Published: April 2012

Polylysine and its copolymers have been extensively used as nonviral polymeric gene carriers. Although polylysine on its own is toxic to cells, when polyethylene glycol is covalently linked to polylysine, toxicity is reduced and DNA transfection efficiency is increased. A degradable polylysine analog, polyaminobutyl glycolic acid, has been synthesized. Stearyl polylysine shows strong hydrophobic interactions with low-density lipoprotein and these components can be combined with DNA to form a “terplex” system that allows delivery of DNA to targeted cells and significant levels of transfection both in vitro and in vivo.
Quantitative Analysis of Drosophila Larval Neuromuscular Junction Morphology
Authors: Andlauer Till F.M. , Sigrist Stephan J.
Published: April 2012

In the past decade, a significant number of proteins involved in the developmental assembly and maturation of synapses have been identified. However, detailed knowledge of the molecular processes underlying developmental synapse assembly is still sparse. We have developed an approach that makes extended in vivo imaging of selected proteins in live Drosophila larvae feasible at a single-synapse resolution. The intact larvae are anesthetized and neuromuscular junctions (NMJs) are noninvasively imaged with confocal microscopy. This method allows for both protein trafficking and protein turnover kinetics to be studied at various points in time during the development of an animal. These data contribute to our understanding of synaptic assembly under in vivo conditions. Image analysis and quantification are best performed in three dimensions (3D; e.g., with the software Imaris by Bitplane), but they can also be performed using a simpler method for two-dimensional (2D) analysis using the free software ImageJ as presented in this protocol. We propose various possibilities for how an analysis may be performed with ImageJ, rather than providing an inflexible protocol, in which the steps must be followed without modifications. Although execution of most of the tools will be described via the ImageJ menu, most are also readily accessible through icons in ImageJ McMaster Biophotonics Facility (MBF) toolsets. These toolsets can also very easily be adapted for higher efficiency.
Cellular Imaging Using Total Internal Reflection Fluorescence Microscopy: Theory and Instrumentation
Authors: Toomre Derek
Published: April 2012

Live cell fluorescent microscopy is important in elucidating dynamic cellular processes such as cell signaling, membrane trafficking, and cytoskeleton remodeling. Often, transient intermediate states are revealed only when imaged and quantitated at the single-molecule, vesicle, or organelle level. Such insight depends on the spatiotemporal resolution and sensitivity of a given microscopy method. Confocal microscopes optically section the cell and improve image contrast and axial resolution (>600 nm) compared with conventional epifluorescence microscopes. Another approach, which can selectively excite fluorophores in an even thinner optical plane (<100 nm) is total internal reflection fluorescence microscopy (TIRFM). The key principle of TIRFM is that a thin, exponentially decaying, evanescent field of excitation can be generated at the interface of two mediums of different refractive index (RI) (e.g., the glass coverslip and the biological specimen); as such, TIRFM is ill-suited to deep imaging of cells or tissue. However, for processes near the lower cell cortex, the sensitivity of TIRFM is exquisite. The recent availability of a very high numerical-aperture (NA) objective lens (>1.45) and turnkey TIRFM systems by all the major microscopy manufacturers has made TIRFM increasingly accessible and attractive to biologists, especially when performed in a quantitative manner and complemented with orthogonal genetic and molecular manipulations. This article discusses the optical principles of TIRFM (including a sample calculation of penetration depth), the components of a TIRFM setup, and the use of TIRFM in combination with other imaging modalities.
Mammaglobin 1: not only a breast‐specific and tumour‐specific marker, but also a hormone‐responsive endometrial protein
Authors: Classen‐Linke Irmgard , Moss Sabine , Gröting Katrin , Beier Henning M , Alfer Joachim , Krusche Claudia A
Published: April 2012

Classen‐Linke I, Moss S, Gröting K, Beier H M, Alfer J & Krusche C A  (2012) Histopathology 61, 955–965

Mammaglobin 1: not only a breast‐specific and tumour‐specific marker, but also a hormone‐responsive endometrial protein

Aims:  The secretoglobin mammaglobin 1 (MGB1) is strongly expressed in breast tumours, and is therefore used to detect breast cancer metastases, although it has also been detected in other tissues. The aim of this study was to examine MGB1 expression and its hormonal regulation in human endometrium to further investigate the use of MGB1 as a marker molecule.

Methods and results:  Mammaglobin 1 expression was assessed immunohistochemically in endometrial samples from 60 normal fertile patients throughout the menstrual cycle, in 49 endometriotic tissue samples, in 15 endometrial adenocarcinomas, and in 36 breast carcinomas. In addition, 25 endometrial samples were analysed by western blot and quantitative real‐time reverse transcription polymerase chain reaction. To prove hormonal regulation, primary endometrial epithelial cells were cultured with 17β‐oestradiol and promegestone. MGB1 was detected in human endometrial tissue, with peak expression during the luteal phase, in 31% of endometriotic samples, in 53% of endometrial adenocarcinomas, and in 64% of breast carcinomas. MGB1 mRNA expression was increased in vitro by hormonal treatment.

Conclusions:  Our data show that MGB1 expression is not restricted to normal and malignant breast tissue. Besides its documented occurrence in endometriotic and malignant endometrial tissues, MGB1 is also expressed in normal human endometrium, and such expression is controlled by steroid hormones.
The cyclophilin ROC1 links phytochrome and cryptochrome to brassinosteroid sensitivity
Authors: Trupkin Santiago A. , Mora‐García Santiago , Casal Jorge J.
Published: April 2012

Although multiple photoreceptors converge to control common aspects of seedling de‐etiolation, we are relatively ignorant of the genes acting at or downstream of their signalling convergence. To address this issue we screened for mutants under a mixture of blue plus far‐red light and identified roc1‐1D. The roc1‐1D mutant, showing elevated expression of the ROTAMASE CYCLOPHILIN 1 (ROC1/AtCYP18‐3) gene, and partial loss‐of function roc1 alleles, has defects in phytochrome A (phyA)‐, cryptochrome 1 (cry1)‐ and phytochrome B (phyB)‐mediated de‐etiolation, including long hypocotyls under blue or far‐red light. These mutants show elevated sensitivity to brassinosteroids in the light but not in the dark. Mutations at brassinosteroid signalling genes and the application of a brassinosteroid synthesis inhibitor eliminated the roc1 and roc1‐D phenotypes. The roc1 and roc1‐D mutants show altered patterns of phosphorylation of the transcription factor BES1, a known point of control of sensitivity to brassinosteroids, which correlate with the expression levels of genes directly targeted by BES1. We propose a model where perception of light by phyA, cry1 or phyB activates ROC1 (at least in part by enhancing its expression). This in turn reduces the intensity of brassinosteroid signalling and fine‐tunes seedling de‐etiolation.