bluuebunny/crossref_metadata_2025 huggingface dataset:
Predator occupancy rates in a thinned ponderosa pine forest, Arizona: A pilot study
Authors: Barrett Kevin J. , Kalies Elizabeth L. , Chambers Carol L.
Published: April 2012

Throughout northern Arizona, USA, forest thinning in ponderosa pine (Pinus ponderosa) forests has become a common practice to reduce the threat of stand‐replacing wildfire and to increase plant and animal diversity across the landscape. To determine how thinning affects predator occurrence, we assessed relationships between predator occupancy and the density of small mammals (prey) across a range of tree stocking levels (basal area of 10–65 m2/ha). Predators were detected using 2 techniques: baited track plates and motion‐sensitive cameras. We sampled 33 sites for 2 weeks each in order to detect presence of predators, and estimated occupancy using occupancy models and multimodel inference. We modeled occupancy rates for gray fox (Urocyon cinereoargenteus), coyote (Canis latrans), and raccoon (Procyon lotor). Our results suggest that thinning may have a positive influence on gray fox and coyote abundance, but a negative influence on raccoon abundance. However, our inability to develop strong models that predicted predator occupancy indicates that higher sample sizes and more habitat covariates are needed. Our simulations indicated that, given our occupancy and detection rates, a sample size of 75 sites would allow us to better model occupancy covariates. Overall, we found that predator occupancy can be assessed at large spatial scales using occupancy approaches, particularly using motion‐sensitive cameras, which were the most time‐ and cost‐efficient of the methods we analyzed. © 2012 The Wildlife Society.
Evaluation of a clutch‐containment method during hatch in geese: Using resident Canada geese as an example
Authors: Guerena Katherine B. , Castelli Paul M. , Nichols Theodore C. , Williams Christopher K.
Published: April 2012

Disruption associated with nest visits during the hatch period of waterfowl can cause partial abandonment of hatchlings, potentially causing bias in the survival of marked birds. We evaluated the use of a mesh clutch‐containment bag to capture and mark entire broods of 151 resident Canada goose (Branta canadensis) nests, prior to hatch, while minimizing observer‐caused disruption during brooding. The study was conducted in New Jersey, USA, from April to June 2010. No differences were found in hatch success or the number of hatchlings marked between contained clutches and the control group. Although this technique was not beneficial in studying gosling survival in temperate nesting populations, it may be effective in sub‐Arctic nesting conditions where nest visits are conducted using a more invasive approach such as a helicopter. © 2012 The Wildlife Society.
Deciphering the complexities of human diseases and disorders by coupling induced‐pluripotent stem cells and systems genetics
Authors: Chang Wing Y. , Garcha Kamal , Manias Janet L. , Stanford William L.
Published: April 2012

The recent discovery that adult mouse and human somatic cells can be ‘reprogrammed’ to a state of pluripotency by ectopic expression of only a few transcription factors has already made a major impact on the biomedical community. For the first time, it is possible to study diseases on an individual patient basis, which may eventually lead to the realization of personalized medicine. The utility of induced‐pluripotent stem cells (iPSCs) for modeling human diseases has greatly benefitted from established human embryonic stem cell (ESC) differentiation and tissue engineering protocols developed to generate many different cell and tissue types. The limited access to preimplantation genetic tested embryos and the difficulty in gene targeting human ESCs have restricted the use of human ESCs in modeling human disease. Afforded by iPSC technology is the ability to study disease pathogenesis as it unfolds during tissue morphogenesis. The complexities of molecular signaling and interplay with protein transduction during disease progression necessitate a systems approach to studying human diseases, whereby data can be statistically integrated by sorting out the signal to noise issues that arise from global biological changes associated with disease versus experimental noise. Using a systems approach, biomarkers can be identified that define the initiation or progression of disease and likewise can serve as putative therapeutic targets. WIREs Syst Biol Med 2012 doi: 10.1002/wsbm.1170

This article is categorized under:

Models of Systems Properties and Processes > Cellular Models

Laboratory Methods and Technologies > Genetic/Genomic Methods

Translational, Genomic, and Systems Medicine > Translational Medicine
Construction of a URA3 deletion strain from the allotetraploid bottom‐fermenting yeast Saccharomyces pastorianus
Authors: Murakami Nobutada , Miyoshi Sae , Yokoyama Ryo , Hoshida Hisashi , Akada Rinji , Ogata Tomoo
Published: April 2012

The bottom‐fermenting lager yeast Saccharomyces pastorianus has been proposed to be allotetraploid, containing two S. cerevisiae (Sc)‐type and two S. bayanus (Sb)‐type chromosomes. This chromosomal constitution likely explains why recessive mutants of S. pastorianus have not previously been reported. Here we describe the construction of a ura3 deletion strain derived from the lager strain Weihenstephan34/70 by targeted transformation and subsequent loss of heterozygosity (LOH). Initially, deletion constructs of the Sc and Sb types of URA3 were constructed in laboratory yeast strains in which a TDH3p‐hygro allele conferring hygromycin B resistance replaced ScURA3 and a KanMX cassette conferring G‐418 resistance replaced SbURA3. The lager strain was then transformed with these constructs to yield a heterozygous URA3 disruptant (ScURA3+/Scura3Δ::TDH3p‐hygro, SbURA3+/Sbura3Δ::KanMX), which was plated on 5‐fluoroorotic acid (5‐FOA) plates to generate the desired Ura– homozygous disruptant (Scura3Δ::TDH3p‐hygro/Scura3Δ::TDH3p‐hygro Sbura3Δ::KanMX/Sbura3Δ::KanMX) through LOH. This ura3 deletion strain was then used to construct a bottom‐fermenting yeast transformant overexpressing ATF1 that encodes an enzyme that produces acetate esters. The ATF1‐overexpressing transformant produced significantly more acetate esters than the parent strain. The constructed ura3∆ lager strain will be a useful host for constructing strains of relevance to brewing. Copyright © 2012 John Wiley & Sons, Ltd.
Do We Overtreat Post‐Thyroidectomy Hypocalcemia?
Authors: Huang Shih‐Ming
Published: April 2012

Background

Calcium and calcitriol supplements are standard for patients with post‐thyroidectomy serum calcium <2.0 mmol/L; however, we wondered whether we overtreat post‐thyroidectomy hypocalcemia with intraoperative parathyroid hormone (PTH). We examined quick‐intraoperative intact PTH (QiPTH) assay results to find a suitable treatment for post‐thyroidectomy hypocalcemia.

Methods

We studied 197 bilateral thyroidectomy patients. Post‐thyroidectomy hypocalcemia was defined as serum calcium <2.0 mmol/L. A QiPTH assay was done 15 min after the thyroidectomy (QiPTH15), and hypoparathyroidism was defined as PTH <15 ng/L. The QiPTH15 assay was used to determine the effects of the thyroidectomy on postoperative PTH levels and serum calcium levels. The natural course and medical response of hypocalcemia was observed in patients with a QiPTH15 ≥15 ng/L.

Results

None of the 187 patients with a QiPTH15 ≥15 ng/L developed postoperative hypoparathyroidism. However, 79 patients developed transient hypocalcemia, and those with Graves’ disease (47/94) had significantly (p < 0.05) higher hypocalcemia than those with non‐Graves’ thyroid disease (32/93). The serum calcium of these 79 patients declined to its lowest level within the first postoperative 18 h. Seven patients with serum calcium <1.75 mmol/L were successfully treated using a calcium supplement only, and the others recovered spontaneously without treatment.

Conclusions

When post‐thyroidectomy QiPTH15 was ≥15 ng/L, postoperative hypoparathyroidism was excluded, but more than one‐third of the patients developed post‐thyroidectomy hypocalcemia. However, most of them recovered without treatment, and a few recovered after taking only a calcium supplement. We believe that using QiPTH15 results as a guide will prevent overtreatment of post‐thyroidectomy hypocalcemia.
Degradation kinetics of 4-amino naphthalene-1-sulfonic acid by a biofilm-forming bacterial consortium under carbon and nitrogen limitations
Authors: Juárez-Ramírez C , Velázquez-García R , Ruiz-Ordaz N , Galíndez-Mayer J , Ramos Monroy O
Published: April 2012

By decolorization of azo dyes, caused by reductive cleavage of the azo linkage, toxic or recalcitrant amines are generated. The present study deals with the effect of the inflowing medium composition (C:N ratio) on the kinetic behavior of a bacterial biofilm-forming consortium, able to use as carbon, nitrogen and sulfur source, the molecule of 4-aminonaphthalene-1-sulfonic acid (4ANS), which is one of the most recalcitrant byproducts generated by decolorization of azo dyes. All the experiments were carried out at room temperature in a lab-scale packed-bed biofilm reactor. Because environmental conditions affect the bioreactor performance, two mineral salts media containing 4ANS, with distinct C:N ratios; 0.68 (carbon as the limiting nutrient) and 8.57 (nitrogen as the limiting nutrient) were used to evaluate their effect on 4ANS biodegradation. By HPLC and COD measurements, the 4ANS removal rates and removal efficiencies were determined. The cultivable bacterial strains that compose the consortium were identified by their 16S rDNA gene sequence. With the enrichment technique used, a microbial consortium able to use efficiently 4ANS as the sole carbon source and energy, nitrogen and sulfur, was selected. The bacterial strains that constitute the consortium were isolated and identified. They belong to the following genera: Bacillus, Arthrobacter, Microbacterium, Nocardioides, and Oleomonas. The results obtained with this consortium showed, under nitrogen limitation, a remarkable increase in the 4ANS removal efficiency ηANS, and in the 4ANS volumetric removal rates R  V,4ANS, as compared to those obtained under carbon limitation. Differences observed in bioreactor performance after changing the nutrient limitation could be caused by changes in biofilm properties and structure.
Gesundheit schützen, Gesundheit fördern – föderal, kommunal
Authors: Benterbusch Reinhild
Published: April 2012

Einleitung

Ein Viertel Jahrhundert ist es nun her, dass die visionäre Ottawa Charta „Health for all“ als gesundheitspolitisches Rahmenkonzept von den WHO Mitgliedstaaten verabschiedet wurde. Der „Gesundheits“-Begriff, den die WHO-Experten der Charta damals zu Grunde legten, basiert nicht primär auf einer biologischen sondern auf einer sozialen Perspektive. Diese lenkt den Blick auf die Lebens-„Bedingungen“ von Menschen, was bedeutet: Gesundheit und Krankheit sind eng verknüpft mit den jeweiligen sozialen, materiellen, kulturellen und umweltbezogenen Lebensbedingungen der Menschen in einer Gesellschaft.
Eine Hochschule als Impulsgeber sozialer Stadtteilentwicklung? Die EH Freiburg und der Freiburger Stadtteil Weingarten
Authors: Dietz Berthold
Published: April 2012

Einleitung

Was hat eine Hochschule in einem Wohngebiet zu suchen? Hochschulen sind häufig eher Eigenareale und in der Regel selbstreferenzielle Bezugspunkte anderer Milieus sind als die, die sie nachbarschaftlich umgeben. Die Evangelische Hochschule Freiburg mag hier ein bisschen aus der Rolle fallen. Sie liegt mitten im größten und sozialstrukturell fragilsten Freiburger Stadtteil Weingarten. In dem, wie sich Hochschule aber für den Sozialraum interessiert und sich in ihn hinein vernetzt, kann sie einen wichtigen Beitrag zur Stadt(teil)entwicklung liefern.
Gesundheitsrisiken und Luftverschmutzung in urbanen Lebensräumen
Authors: Zscheppang Anja , Kirch Wilhelm
Published: April 2012

Einleitung

Gesundheit ist ein hohes Gut, welches möglichst lange erhalten bleiben soll. Ob ein Mensch gesund ist, hängt von vielen Einflussfaktoren ab. Ein Faktor, der lange Zeit kaum Beachtung fand, jedoch nachweislich den Gesundheitszustand der Menschen beeinflussen kann, ist die Luftqualität. Luft und damit auch Schadstoffe umgeben uns sowohl im Freien als auch in Innenräumen in unterschiedlicher Konzentration. Sie wirken sich in bestimmten Konzentrationen nachweislich negativ auf die Gesundheit aus.
The Bonneville Estates Rockshelter rodent fauna and changes in Late Pleistocene–Middle Holocene climates and biogeography in the Northern Bonneville Basin, USA
Authors: Schmitt Dave N. , Lupo Karen D.
Published: April 2012

Excavations at Bonneville Estates Rockshelter, Nevada recovered rodent remains from stratified deposits spanning the past ca. 12,50014C yr BP (14,800 cal yr BP). Specimens from horizons dating to the late Pleistocene and early Holocene include species adapted to montane and moist and cool habitats, including yellow-bellied marmot (Marmota flaviventris) and bushy-tailed woodrat (Neotoma cinerea). Shortly after 900014C BP (10,200 cal yr BP) these mammals became locally extinct, or nearly so, taxonomic diversity declined, and the region became dominated by desert woodrats (Neotoma lepida) and other species well-adapted to xeric, low-elevation settings. The timing and nature of changes in the Bonneville Estates rodent fauna are similar to records reported from nearby Homestead and Camels Back caves and provide corroborative data on terminal Pleistocene–early Holocene environments and mammalian responses to middle Holocene desertification. Moreover, the presence of northern pocket gopher (Thomomys talpoides) at Bonneville Estates adds to a sparse regional record for that species and similar to Homestead Cave, it appears that the ca. 950014C yr BP (10,800 cal yr BP) replacement of the northern pocket gopher by Botta's pocket gopher in the Great Salt Lake Desert vicinity was also in response to climate change.
Opioid receptor heteromers in analgesia
Authors: Costantino Cristina M. , Gomes Ivone , Stockton Steven D. , Lim Maribel P. , Devi Lakshmi A.
Published: April 2012

Opiates such as morphine and fentanyl, a major class of analgesics used in the clinical management of pain, exert their effects through the activation of opioid receptors. Opioids are among the most commonly prescribed and frequently abused drugs in the USA; however, the prolonged use of opiates often leads to the development of tolerance and addiction. Although blockade of opioid receptors with antagonists such as naltrexone and naloxone can lessen addictive impulses and facilitate recovery from overdose, systemic disruption of endogenous opioid receptor signalling through the use of these antagonistic drugs can have severe side effects. In the light of these challenges, current efforts have focused on identifying new therapeutic targets that selectively and specifically modulate opioid receptor signalling and function so as to achieve analgesia without the adverse effects associated with chronic opiate use. We have previously reported that opioid receptors interact with each other to form heteromeric complexes and that these interactions affect morphine signalling. Since chronic morphine administration leads to an enhanced level of these heteromers, these opioid receptor heteromeric complexes represent novel therapeutic targets for the treatment of pain and opiate addiction. In this review, we discuss the role of heteromeric opioid receptor complexes with a focus on mu opioid receptor (MOR) and delta opioid receptor (DOR) heteromers. We also highlight the evidence for altered pharmacological properties of opioid ligands and changes in ligand function resulting from the heteromer formation.
Introduction
Authors: Franceschet Antonio
Published: April 2012

Within a short period the International Criminal Court (ICC) has become central to world politics. The dramatic diplomatic process that produced the Rome Statute in 1998 was followed by an unexpectedly rapid succession of state ratifications and the establishment of the court in 2002. As of late 2011 the ICC has indicted twenty-six individuals related to seven official investigations, all in Africa. Proceedings against one of these individuals were dismissed. Two other indictments, including one for Libya's Muammar Qaddafi, became moot because the individuals were killed before arrest or trial. The remaining list includes a sitting head of state, Sudanese president Omar al-Bashir, as well as Kenya's sitting deputy prime minister, Uhuru Kenyatta. The United Nations Security Council referred both the Sudan and Libya situations to the court; three African states requested investigations of their own situations. The ICC prosecutor independently started an investigation in Kenya. Despite efforts by Kenyan state officials to halt ICC proceedings related to the widespread violence and killings following the 2007 national elections, opinion polls suggest that 73 percent of Kenyans want the ICC to remain involved.
Why the ICC Should Operate Within Peace Processes
Authors: Rodman Kenneth A.
Published: April 2012

Is it ethical for the prosecutor at the International Criminal Court (ICC) to consider political factors, such as peace processes, in selecting situations to investigate or cases to prosecute? During the early years of the court, a number of documents and statements from the Office of the Prosecutor (OTP) suggested that there were occasions when it was. Two OTP policy papers issued in 2003 recommended that the prosecutor assess “all circumstances prevailing in the country or region concerned, including the nature and stage of the conflict and any intervention by the international community,” and whether prosecution might “exacerbate or otherwise destabilize a conflict situation.” In the same spirit, the ICC's chief prosecutor, Luis Moreno-Ocampo, referred to his decision-making as a “dialogue between many actors” with a “strategic dimension . . . [that] involves all stakeholders.” This language suggested a process of consultation and coordination with local and international actors involved in conflict resolution to adapt international criminal justice to on-the-ground political realities.
The International Criminal Court's Provisional Authority to Coerce
Authors: Franceschet Antonio
Published: April 2012

The United Nations ad hoc tribunals in the former Yugoslavia and Rwanda had primacy over national judicial agents for crimes committed in these countries during the most notorious civil wars and genocide of the 1990s. The UN Charter granted the Security Council the right to establish a tribunal for Yugoslavia in the context of ongoing civil war and against the will of recalcitrant national agents. The Council used that same right to punish individuals responsible for a genocide that it failed earlier to prevent in Rwanda. In both cases the Council delegated a portion of its coercive title to independent tribunal agents, thereby overriding the default locus of punishment in the world order: sovereign states.
Reimagining a Global Ethic
Authors: Ignatieff Michael
Published: April 2012

“Reimagining a global ethic” is a project worthy of Andrew Carnegie and of the Carnegie Council's upcoming commemoration of his founding gift in 1914. As a collaborative research project stretching forward over the next three years, it ought to be integrative and reconciliatory: that is, it must try to understand the globalization of ethics that has accompanied the globalization of commerce and communications and to figure out what ethical values human beings share across all our differences of race, religion, ethnicity, national identity, and material wealth. When human beings do disagree morally, the search for a global ethic becomes an attempt to elucidate by analysis what exactly people are disagreeing about, so that, after arguing out our differences, we can either agree to disagree or work together to find common ground. Finding common ground on large ethical matters and understanding more deeply why, in some instances, we remain at odds with each other is worthwhile in itself, but it might also further Andrew Carnegie's original goal in founding the Council, which was to reduce the amount of conflict and violence in the world.
A Brief Response to Michael Ignatieff
Authors: Smith Michael Joseph
Published: April 2012

In his elegant essay on the tension between a singular global ethic and global ethics in the plural, Michael Ignatieff invites us to “think harder about the conflicts of principle between them.” He is certainly right that harder thinking is needed: advocates of both versions of a global ethic sometimes seem locked into mutual self-righteousness. What we might call singular, or universal, ethicists often accuse pluralists of parochial atavism, while the partisans of plural, usually national, ethics think that the universalists are naive at best, arrogant at worst. Both are utterly convinced that they are right.
Local Priorities, Universal Priorities, and Enabling Harm
Authors: Barry Christian
Published: April 2012

“National communities,” Michael Ignatieff writes in his thoughtful essay on the prospects for a global ethic, “have some good reasons, as well as some not so good ones, to privilege local ahead of universal priorities and interests.” And he goes on to explain the clash of local and universal priorities as rooted in a conflict between the values of “justice and democracy.” I would rather suggest that the conflict is an internal one—a conflict inherent in our thinking about what justice requires. But in any case, he is surely right that providing a compelling account of how to distinguish good from bad reasons for privileging local priorities, and identifying how weighty the good reasons for local priorities are, is fundamental to developing a plausible global ethic.
A Global Ethic and the Hybrid Character of the Moral World
Authors: Rengger Nicholas
Published: April 2012

In the lead essay of this symposium, Michael Ignatieff offers a characteristic blend of philosophical acuteness and political good sense on a topic that, we can all agree, is central to many of the most important questions on the contemporary political and international agenda. His analysis is prescient, challenging, and deserves pondering at some length; thus, in this short response I cannot deal with it in anything like the detail it deserves. But the enforced brevity is perhaps an advantage as well, in that it forces me to concentrate on where I differ from Ignatieff and on my own sense of what we might imply when we use such a term as “a global ethic.”
The Dialogue of Global Ethics
Authors: Ryan Cheyney
Published: April 2012

The message of Michael Ignatieff's reflections on reimagining a global ethic is a comforting one for political philosophers. It is vital, he writes, for philosophers to keep doing what they have been doing: addressing the injustices of globalization from a perspective of strict impartiality that treats every human being as the object of equal moral concern. Philosophers should continue to elaborate this “one world” perspective against those partial perspectives arising from the claims of one's particular country or particular religious faith. But their aim should not be to replace the one with the other, but to prompt an ongoing critical dialogue in which more particularistic doctrines of country or faith are called to justify themselves before the one-world ethic's impartial standards—thus prompting the kind of critical self-reflection that is essential to moral change. And in so doing, the one-world ethic cannot be uncritical of itself, for there are different ways of conceiving a global ethic, each of which must answer to the others.
Vlasov simulation of electrostatic solitary structures in multi‐component plasmas
Authors: Umeda Takayuki , Ashour‐Abdalla Maha , Pickett Jolene S. , Goldstein Melvyn L.
Published: April 2012

Electrostatic solitary structures have been observed in the Earth's magnetosheath by the Cluster spacecraft. Recent theoretical work has suggested that these solitary structures are modeled by electron acoustic solitary waves existing in a four‐component plasma system consisting of core electrons, two counter‐streaming electron beams, and one species of background ions. In this paper, the excitation of electron acoustic waves and the formation of solitary structures are studied by means of a one‐dimensional electrostatic Vlasov simulation. The present result first shows that either electron acoustic solitary waves with negative potential or electron phase‐space holes with positive potential are excited in four‐component plasma systems. However, these electrostatic solitary structures have longer duration times and higher wave amplitudes than the solitary structures observed in the magnetosheath. The result indicates that a high‐speed and small free energy source may be needed as a fifth component. An additional simulation of a five‐component plasma consisting of a stable four‐component plasma and a weak electron beam shows the generation of small and fast electron phase‐space holes by the bump‐on‐tail instability. The physical properties of the small and fast electron phase‐space holes are very similar to those obtained by the previous theoretical analysis. The amplitude and duration time of solitary structures in the simulation are also in agreement with the Cluster observation.
Numerical simulation of the effects of a solar energetic particle event on the ionosphere of Mars
Authors: Sheel Varun , Haider S. A. , Withers Paul , Kozarev K. , Jun I. , Kang S. , Gronoff G. , Simon Wedlund C.
Published: April 2012

We investigate the ionospheric effects of a solar energetic particle (SEP) event at Mars, specifically the 29 September 1989 event. We use its energy spectrum and a steady state ionospheric model to simulate vertical profiles of ion and electron densities. The ionospheric response to this large event would have been readily observable. It caused electron densities to exceed 104 cm−3 at 30–170 km, much larger than typically observed below 100 km. It also increased the ionosphere's total electron content by half of its subsolar value and would have caused strong attenuation of radio waves. The simulated attenuation is 462 dB at 5 MHz, which demonstrates that SEP events can cause sufficient attenuation (>13 dB) to explain the lack of surface reflections in some MARSIS topside radar sounder observations. We also develop a complementary generalized approach to the study of the ionospheric effects of SEP events. This approach predicts the threshold intensities at which a SEP event is likely to produce detectable changes in electron density profiles and radio wave attenuation measurements. An event one hundred times less intense than the 29 September 1989 event produces electron densities in excess of 3000 cm−3 at 80 km, which should be measurable by radio occultation observations, and causes sufficient attenuation to eliminate MARSIS surface reflections. However, although enhancements in total electron content have been observed during SEP events, predicted enhancements in low altitude electron density were not confirmed by observations.
Observational evidence from direct current measurements for propagation of remotely forced waves on the shelf off the west coast of India
Authors: Amol P. , Shankar D. , Aparna S. G. , Shenoi S. S. C. , Fernando V. , Shetye S. R. , Mukherjee A. , Agarvadekar Y. , Khalap S. , Satelkar N. P.
Published: April 2012

We use data from six Acoustic Doppler Current Profiler (ADCP) moorings deployed during March–September 2008 on the continental shelf and slope off Bhatkal, Goa, and Jaigarh on the central west coast of India to present evidence for poleward propagation of shelf or coastal‐trapped waves (CTWs). Wave propagation is seen on the shelf in the 20–40‐day, 10–14‐day, and 3–5‐day‐period bands. The lag from south to north indicates that remote forcing is important even at periods as short as 4 days. Using QuikSCAT wind data, we show that the contribution of remote forcing to the shelf West Indian Coastal Current (WICC) is significant even when the local alongshore wind is strong, as during the summer‐monsoon onset during May–June, and forces a strong local response that masks the effect of remote forcing. Forced wave calculations using CTW theory show that remote forcing of the WICC is present at all times, but is most striking when the local winds are weak, as during March–April. The CTW calculations show that the source region for the remote forcing may extend beyond the west coast into the Gulf of Mannar between India and Sri Lanka. On the slope, propagation is seen only at the 4‐day period. At higher periods, the slope WICC decorrelates rapidly along the coast, but upward phase propagation, implying downward propagation of energy associated with poleward propagation, is evident even at these higher periods.
Field measurement of upper ocean turbulence dissipation associated with wave‐turbulence interaction in the South China Sea
Authors: Huang Chuan Jiang , Qiao Fangli , Dai Dejun , Ma Hongyu , Guo Jingsong
Published: April 2012

The turbulence dissipation rate within the mixed layer was measured in the open ocean and the coastal water of the South China Sea under moderate winds of 4.7 ∼ 8.9 m s−1 using a free‐falling MSS profiler. In the open ocean, the profile of the dissipation rate within the mixed layer exhibited an exponential decay with the depth at most stations, which was satisfactorily consistent with that predicted by the parameterization of wave‐turbulence interaction presented by Huang and Qiao (2010) while deviating from that by the law of the wall. In the coastal ocean, however, both the parameterization of wave‐turbulence interaction and the law of the wall can give approximate predictions to the measured dissipation rate.
The roles of charge exchange and dissociation in spreading Saturn's neutral clouds
Authors: Fleshman B. L. , Delamere P. A. , Bagenal F. , Cassidy T.
Published: April 2012

Neutrals sourced directly from Enceladus's plumes are initially confined to a dense neutral torus in Enceladus's orbit around Saturn. This neutral torus is redistributed by charge exchange, impact/photodissociation, and neutral‐neutral collisions to produce Saturn's neutral clouds. Here we consider the former processes in greater detail than in previous studies. In the case of dissociation, models have assumed that OH is produced with a single speed of 1 km s−1, whereas laboratory measurements suggest a range of speeds between 1 and 1.6 km s−1. We show that the high‐speed case increases dissociation's range of influence from 9 to 15 RS. For charge exchange, we present a new modeling approach, where the ions are followed within a neutral background, whereas neutral cloud models are conventionally constructed from the neutrals' point of view. This approach allows us to comment on the significance of the ions' gyrophase at the moment charge exchange occurs. Accounting for gyrophase (1) has no consequence on the H2O cloud, (2) doubles the local density of OH at the orbit of Enceladus, and (3) decreases the oxygen densities at Enceladus's orbit by less than 10%. Finally, we consider velocity‐dependent, as well as species‐dependent cross sections and find that the oxygen cloud produced from charge exchange is spread out more than H2O, whereas the OH cloud is the most confined.
Antarctic surface melting dynamics: Enhanced perspectives from radar scatterometer data
Authors: Trusel L. D. , Frey K. E. , Das S. B.
Published: April 2012

Antarctic ice sheet surface melting can regionally influence ice shelf stability, mass balance, and glacier dynamics, in addition to modulating near‐surface physical and chemical properties over wide areas. Here, we investigate variability in surface melting from 1999 to 2009 using radar backscatter time series from the SeaWinds scatterometer aboard the QuikSCAT satellite. These daily, continent‐wide observations are explored in concert with in situ meteorological records to validate a threshold‐based melt detection method. Radar backscatter decreases during melting are significantly correlated with in situ positive degree‐days as well as meltwater production determined from energy balance modeling at Neumayer Station, East Antarctica. These results support the use of scatterometer data as a diagnostic indicator of melt intensity (i.e., the relative liquid water production during melting). Greater spatial and temporal melting detected relative to previous passive microwave‐based studies is attributed to a higher sensitivity of the scatterometer instrument. Continental melt intensity variability can be explained in part by the dynamics of the Southern Annular Mode and the Southern Oscillation Index, and extreme melting events across the Ross Ice Shelf region may be associated with El Niño conditions. Furthermore, we find that the Antarctic Peninsula accounts for only 20% of Antarctic melt extent but greater than 50% of the total Antarctic melt intensity. Over most areas, annual melt duration and intensity are proportional. However, regional and localized distinctions exist where the melt intensity metric provides greater insight into melting dynamics than previously obtainable with other remote sensing techniques.
Rapid switches in subpolar North Atlantic hydrography and climate during the Last Interglacial (MIS 5e)
Authors: Irvalı Nil , Ninnemann Ulysses S. , Galaasen Eirik V. , Rosenthal Yair , Kroon Dick , Oppo Delia W. , Kleiven Helga F. , Darling Kate F. , Kissel Catherine
Published: April 2012

At the peak of the previous interglacial period, North Atlantic and subpolar climate shared many features in common with projections of our future climate, including warmer‐than‐present conditions and a diminished Greenland Ice Sheet (GIS). Here we portray changes in North Atlantic hydrography linked with Greenland climate during Marine Isotope Stage (MIS) 5e using (sub)centennially sampled records of planktonic foraminiferal isotopes and assemblage counts and ice‐rafted debris counts, as well as modern analog technique and Mg/Ca‐based paleothermometry. We use the core MD03‐2664 recovered from a high accumulation rate site (∼34 cm/kyr) on the Eirik sediment drift (57°26.34′N, 48°36.35′W). The results indicate that surface waters off southern Greenland were ∼3–5°C warmer than today during early MIS 5e. These anomalously warm sea surface temperatures (SSTs) prevailed until the isotopic peak of MIS 5e when they were interrupted by a cooling event beginning at ∼126 kyr BP. This interglacial cooling event is followed by a gradual warming with SSTs subsequently plateauing just below early MIS 5e values. A planktonic δ18O minimum during the cooling event indicates that marked freshening of the surface waters accompanied the cooling. We suggest that switches in the subpolar gyre hydrography occurred during a warmer climate, involving regional changes in freshwater fluxes/balance and East Greenland Current influence in the study area. The nature of these hydrographic transitions suggests that they are most likely related to large‐scale circulation dynamics, potentially amplified by GIS meltwater influences.
Constraints on brittle field exhumation of the Everest‐Makalu section of the Greater Himalayan Sequence: Implications for models of crustal flow
Authors: Streule Michael J. , Carter Andrew , Searle Michael P. , Cottle John M.
Published: April 2012

New apatite and zircon fission track (FT) data from the summit slopes of Everest and along the Barun, Arun, Dudh Kosi, and Kangshung valleys that drain the Everest and Makalu massifs cover a vertical sample transect of almost 8000 m of the Eastern Nepal Greater Himalayan Sequence (GHS). Apatite FT ages range from 0.9 ± 0.3 Ma to 3.1 ± 0.3 Ma in the GHS with ages increasing systematically with elevation. Apatite FT ages in the Everest Series and summit Ordovician limestones are much older, up to 30.5 ± 5.1 Ma. Zircon FT ages from the GHS range from 3.8 ± 0.4 Ma to 16.3 ± 0.8 Ma. The brittle exhumation rates calculated from these data show the GHS was exhumed, since ∼9 Ma, at an average rate of 1.0 ± 0.2 mm/a. Pliocene exhumation rates are higher at 1.7 ± 0.3 mm/a. These values are not significantly different from the estimate of ductile exhumation rates of 1.8 mm/a recorded by metamorphic minerals undergoing decompression between 18.7 and 15.6 Ma but are well below the values (up to 10 mm/a) used by thermomechanical models for ductile channel flow in the GHS. If representative of the GHS these models will therefore require further ‘tuning’. Higher exhumation rates in the Pliocene have also been observed in other parts of the Himalaya and points to a regional cause, likely increased erosion due to the onset of late Pliocene–Pleistocene glaciation of the high Himalaya.
Increasing subsurface water storage in discontinuous permafrost areas of the Lena River basin, Eurasia, detected from GRACE
Authors: Velicogna I. , Tong J. , Zhang T. , Kimball J. S.
Published: April 2012

We use monthly measurements of time‐variable gravity from the GRACE (Gravity Recovery and Climate Experiment) satellite mission to quantify changes in terrestrial water storage (TWS) in the Lena river basin, Eurasia, during the period April 2002 to September 2010. We estimate a TWS increase of 32 ± 10 km3/yr for the entire basin, equivalent to an increase in water thickness of 1.3 ± 0.4 cm/yr over a basin of 2.4 million km2. We compare TWS estimates from GRACE with time series of precipitation (P) minus evapotranspiration (ET) from ERA‐Interim reanalysis minus observational river discharge (R). We find an excellent agreement in annual and inter‐annual variability between the two time series. Furthermore, we find that a bias of −20 ± 10% in P‐ET is sufficient to effectively close the water budget with GRACE. When we account for this bias, the time series of cumulative TWS from GRACE and climatological data agree to within ±3.8 cm of water thickness, or ±9% of the mean annual P. The TWS increase is not uniform across the river basin and exhibits a peak, over an area of 502,400 km2, centered at 118.5°E, 62.5°N, and underlain by discontinuous permafrost. In this region, we attribute the observed TWS increase of 68 ± 19 km3 to an increase in subsurface water storage. This large subsurface water signal will have a significant impact on the terrestrial hydrology of the region, including increased baseflow and alteration of seasonal runoff.
Stemness as a cell default state
Authors: Casanova Jordi
Published: April 2012

Could it be that stemness is not a specific fate resulting from a distinct stem‐cell programme, but simply a result of a stem cell escaping ulterior differentiation? Stemness could be entirely intrinsic to non‐differentiated cells.
Back down to Earth
Authors: Hunter Philip
Published: April 2012

Despite not yet living up to the early hype, systems biology has become an integral component of biological research and should soon yield its first tangible results.
Interferon signatures in immune disorders and disease
Authors: Forster Samuel
Published: April 2012

The interferon (IFN) family and the type‐I IFNs specifically have an important and well‐characterized role in antiviral defence, immune modulation and cell‐cycle control and are regularly applied in the clinical context. Advances in high‐content technologies have facilitated an enhanced understanding of the global IFN response capable of being induced. Recent application of these technologies is improving our understanding of the specificity and subtleties associated with this response. This review considers our current understanding of the temporal gene profile induced through IFN stimulation across a diversity of disease conditions including autoimmune diseases, bacterial and viral infections. Understanding these signatures, the disease‐specific differences and the biological effects induced has the potential to facilitate IFN‐driven therapeutic development.
Nonlinear viscoelasticity of freestanding and polymer-anchored vertically aligned carbon nanotube foams
Authors: Lattanzi Ludovica , Raney Jordan R. , De Nardo Luigi , Misra Abha , Daraio Chiara
Published: April 2012

Vertical arrays of carbon nanotubes (VACNTs) show unique mechanical behavior in compression, with a highly nonlinear response similar to that of open cell foams and the ability to recover large deformations. Here, we study the viscoelastic response of both freestanding VACNT arrays and sandwich structures composed of a VACNT array partially embedded between two layers of poly(dimethylsiloxane) (PDMS) and bucky paper. The VACNTs tested are ∼2 mm thick foams grown via an injection chemical vapor deposition method. Both freestanding and sandwich structures exhibit a time-dependent behavior under compression. A power-law function of time is used to describe the main features observed in creep and stress-relaxation tests. The power-law exponents show nonlinear viscoelastic behavior in which the rate of creep is dependent upon the stress level and the rate of stress relaxation is dependent upon the strain level. The results show a marginal effect of the thin PDMS/bucky paper layers on the viscoelastic responses. At high strain levels (ɛ = 0.8), the peak stress for the anchored CNTs reaches ∼45 MPa, whereas it is only ∼15 MPa for freestanding CNTs, suggesting a large effect of PDMS on the structural response of the sandwich structures.
Determination of the absolute internal quantum efficiency of photoluminescence in GaN co-doped with Si and Zn
Authors: Reshchikov M. A. , Foussekis M. , McNamara J. D. , Behrends A. , Bakin A. , Waag A.
Published: April 2012

The optical properties of high-quality GaN co-doped with silicon and zinc are investigated by using temperature-dependent continuous-wave and time-resolved photoluminescence measurements. The blue luminescence band is related to the ZnGa acceptor in GaN:Si,Zn, which exhibits an exceptionally high absolute internal quantum efficiency (IQE). An IQE above 90% was calculated for several samples having different concentrations of Zn. Accurate and reliable values of the IQE were obtained by using several approaches based on rate equations. The concentrations of the ZnGa acceptors and free electrons were also estimated from the photoluminescence measurements.
Anisotropic oxidation of bismuth nanostructures: Evidence for a thin film allotrope of bismuth
Authors: Kowalczyk P. J. , Belic D. , Mahapatra O. , Brown S. A. , Kadantsev E. S. , Woo T. K. , Ingham B. , Kozlowski W.
Published: April 2012

We present evidence that ultra-thin Bi(110) nanostructures oxidise from the edges, and that their top surfaces remain unoxidised. Even after prolonged oxidation, clean (unoxidised) bismuth is present in nanostructures that are less than 5 monolayers thick. Since the (110) surface of bulk bismuth is known to be readily oxidised, this is strong evidence for a thin film allotrope of bismuth. We present a comparison with calculated structures and the structures of polymeric nitrogen, which suggests that the allotrope is one of several complex or hybrid paired-layer structures.
Analytical solution for the depolarization of hyperpolarized nuclei by chemical exchange saturation transfer between free and encapsulated xenon (HyperCEST)
Authors: Zaiss Moritz , Schnurr Matthias , Bachert Peter
Published: April 2012

We present an analytical solution of the Bloch–McConnell equations for the case of chemical exchange saturation transfer between hyperpolarized nuclei in cavities and in solvent (HyperCEST experiment). This allows quantitative investigation of host–guest interactions by means of nuclear magnetic resonance spectroscopy and, due to the strong HyperCEST signal enhancement, even NMR imaging. Hosts of interest can be hydrophobic cavities in macromolecules or artificial cages like cryptophane-A which was proposed as a targeted biosensor. Relevant system parameters as exchange rate and host concentration can be obtained from the monoexponential depolarization process which is shown to be governed by the smallest eigenvalue in modulus. For this dominant eigenvalue we present a useful approximation leading to the depolarization rate for the case of on- and off-resonant irradiation. It is shown that this rate is a generalization of the longitudinal relaxation rate in the rotating frame. We demonstrate for the free and cryptophane-A-encapsulated xenon system, by comparison with numerical simulations, that HyperCEST experiments are precisely described in the valid range of this widely applicable analytical approximation. Altogether, the proposed analytical solution allows optimization and quantitative analysis of HyperCEST experiments but also characterization and optimal design of possible biosensors.
The critical behavior of the refractive index near liquid-liquid critical points
Authors: Losada-Pérez Patricia , Glorieux Christ , Thoen Jan
Published: April 2012

The nature of the critical behavior in the refractive index n is revisited in the framework of the complete scaling formulation. A comparison is made with the critical behavior of n as derived from the Lorentz-Lorenz equation. Analogue anomalies to those predicted for the dielectric constant ɛ, namely, a leading |t|2β singularity in the coexistence-curve diameter in the two-phase region and a |t|1−α along the critical isopleth in the one phase region, are expected in both cases. However, significant differences as regards the amplitudes of both singularities are obtained from the two approaches. Analysis of some literature data along coexistence in the two-phase region and along the critical isopleth in the one-phase region provide evidence of an intrinsic effect, independent of the density, in the critical anomalies of n. This effect is governed by the shift of the critical temperature with an electric field, which is supposed to take smaller values at optical frequencies than at low frequencies in the Hz to MHz range.
Turbulence measurements in a rotating magnetic field driven flow
Authors: Cramer A. , Pal J. , Gerbeth G.
Published: April 2012

Four-wire electric potential difference probes are used to record time series of two local velocity components in a flow driven by a rotating magnetic field. It is demonstrated that statistical properties of turbulence in an electromagnetically driven flow can be extracted from the signals, although they are predominated by noise, disturbances mainly owing to the operation of switching power supplies in modern installations, and filter characteristics of the data acquisition system. For three physical systems, which are two experimental cells with significantly different sizes filled with different melts and two magnetic systems, it is shown that the micro-Eulerian scale exhibits a power law dependence on the mean flow velocity over a range of the dimensionless driving force, the Taylor number, of more than three orders of magnitude. In terms of Reynolds numbers, this range starts in the transitional regime slightly above the threshold of instability and spreads two orders of magnitude. It is examined whether the flow with the highest velocities might be called a developed turbulent regime. Energy spectra are calculated from the time series and are discussed in the framework of existing theory.
Towards precise measurement of oscillatory domain wall by ferromagnetic Josephson junction
Authors: Hikino Shin’ichi , Mori Michiyasu , Koshibae Wataru , Maekawa Sadamichi
Published: April 2012

We theoretically propose a principle for precise measurement of oscillatory domain wall (DW) by a ferromagnetic Josephson junction, which is composed of a ferromagnetic wire with DW and two superconducting electrodes. The current-voltage curve exhibits stepwise structures, only when DW oscillates in the ferromagnetic wire. The voltage step appears at V=n(ℏ/2e)ωDW with the fundamental constant ℏ/e, integer number n, and the DW frequency ωDW. Since V can be determined in the order of 10−9 accuracy, the oscillatory DW will be measured more precisely than present status by conventional method.