bluuebunny/crossref_metadata_2025 huggingface dataset:
Fast simulation of large‐scale growth models
Authors: Friedrich Tobias , Levine Lionel
Published: February 2012

We give an algorithm that computes the final state of certain growth models without computing all intermediate states. Our technique is based on a “least action principle” which characterizes the odometer function of the growth process. Starting from an approximation for the odometer, we successively correct under‐ and overestimates and provably arrive at the correct final state. Internal diffusion‐limited aggregation (IDLA) is one of the models amenable to our technique. The boundary fluctuations in IDLA were recently proved to be at most logarithmic in the size of the growth cluster, but the constant in front of the logarithm is still not known. As an application of our method, we calculate the size of fluctuations over two orders of magnitude beyond previous simulations, and use the results to estimate this constant. © 2012 Wiley Periodicals, Inc. Random Struct. Alg., 2012
Causal inference in epidemiological studies with strong confounding
Authors: Moore Kelly L. , Neugebauer Romain , van der Laan Mark J. , Tager Ira B.
Published: February 2012

One of the identifiability assumptions of causal effects defined by marginal structural model (MSM) parameters is the experimental treatment assignment (ETA) assumption. Practical violations of this assumption frequently occur in data analysis when certain exposures are rarely observed within some strata of the population. The inverse probability of treatment weighted (IPTW) estimator is particularly sensitive to violations of this assumption; however, we demonstrate that this is a problem for all estimators of causal effects. This is due to the fact that the ETA assumption is about information (or lack thereof) in the data. A new class of causal models, causal models for realistic individualized exposure rules (CMRIER), is based on dynamic interventions. CMRIER generalize MSM, and their parameters remain fully identifiable from the observed data, even when the ETA assumption is violated, if the dynamic interventions are set to be realistic. Examples of such realistic interventions are provided. We argue that causal effects defined by CMRIER may be more appropriate in many situations, particularly those with policy considerations. Through simulation studies, we examine the performance of the IPTW estimator of the CMRIER parameters in contrast to that of the MSM parameters. We also apply the methodology to a real data analysis in air pollution epidemiology to illustrate the interpretation of the causal effects defined by CMRIER. Copyright © 2012 John Wiley & Sons, Ltd.
Augmented generalized estimating equations for improving efficiency and validity of estimation in cluster randomized trials by leveraging cluster‐level and individual‐level covariates
Authors: Stephens Alisa J. , Tchetgen Tchetgen Eric J. , Gruttola Victor De
Published: February 2012

Recent methodological advances in covariate adjustment in randomized clinical trials have used semiparametric theory to improve efficiency of inferences by incorporating baseline covariates; these methods have focused on independent outcomes. We modify one of these approaches, augmentation of standard estimators, for use within cluster randomized trials in which treatments are assigned to groups of individuals, thereby inducing correlation. We demonstrate the potential for imbalance correction and efficiency improvement through consideration of both cluster‐level covariates and individual‐level covariates. To improve small‐sample estimation, we consider several variance adjustments. We evaluate this approach for continuous and binary outcomes through simulation and apply it to data from a cluster randomized trial of a community behavioral intervention related to HIV prevention in Tanzania. Copyright © 2012 John Wiley & Sons, Ltd.
Ignoring overdispersion in hierarchical loglinear models: Possible problems and solutions
Authors: Milanzi Elasma , Alonso Ariel , Molenberghs Geert
Published: February 2012

Poisson data frequently exhibit overdispersion; and, for univariate models, many options exist to circumvent this problem. Nonetheless, in complex scenarios, for example, in longitudinal studies, accounting for overdispersion is a more challenging task. Recently, Molenberghs et.al, presented a model that accounts for overdispersion by combining two sets of random effects. However, introducing a new set of random effects implies additional distributional assumptions for intrinsically unobservable variables, which has not been considered before. Using the combined model as a framework, we explored the impact of ignoring overdispersion in complex longitudinal settings via simulations. Furthermore, we evaluated the effect of misspecifying the random‐effects distribution on both the combined model and the classical Poisson hierarchical model. Our results indicate that even though inferences may be affected by ignored overdispersion, the combined model is a promising tool in this scenario. Copyright © 2012 John Wiley & Sons, Ltd.
Dropouts in the AB/BA crossover design
Authors: Ho Weang Kee , Matthews John N.S. , Henderson Robin , Farewell Daniel , Rodgers Lauren R.
Published: February 2012

Missing data arise in crossover trials, as they do in any form of clinical trial. Several papers have addressed the problems that missing data create, although almost all of these assume that the probability that a planned observation is missing does not depend on the value that would have been observed; that is, the data are missing at random (MAR). In many applications, this assumption is likely to be untenable; in which case, the data are missing not at random (MNAR). We investigate the effect on estimates of the treatment effect that assume data are MAR when data are actually MNAR. We also propose using the assumption of no carryover treatment effect, which is usually required for this design, to permit the estimation of a treatment effect when data are MNAR. The results are applied to a trial comparing two treatments for neuropathic pain and show that the estimate of treatment effect is sensitive to the assumption of MAR. Copyright © 2012 John Wiley & Sons, Ltd.
Current advances in Phi29 pRNA biology and its application in drug delivery
Authors: Ye Xin , Hemida Maged , Zhang Huifang M. , Hanson Paul , Ye Qiu , Yang Decheng
Published: February 2012

Bacteriophage 29 (Phi29) packaging RNA (pRNA) is one of the key components in the viral DNA‐packaging motor. It contains two functional domains facilitating the translocation of DNA into the viral capsid by interacting with other elements in the motor and promoting adenosine triphosphates hydrolysis. Through the connection between interlocking loops in adjacent pRNA monomers, pRNA functions in the form of multimer ring in the motor. Previous studies have addressed the unique structure and conformation of pRNA. However, there are different DNA‐packaging models proposed for the viral genome transportation mechanism. The DNA‐packaging ability and the unique features of pRNA have been attracting efforts to study its potential applications in nanotechnology. The pRNA has been proved to be a promising tool for delivering nucleic acid‐based therapeutic molecules by covalent linkage with ribozymes, small interfering RNAs, aptamers, and artificial microRNAs. The flexibility in constructing dimers, trimers, and hexamers enables the assembly of polyvalent nanoparticles to carry drug molecules for therapeutic purposes, cell ligands for target delivery, image detector for drug entry monitoring, and endosome disrupter for drug release. Besides these fascinating pharmacological advantages, pRNA‐based drug delivery has also been demonstrated to prolong the drug half life with minimal induction of immune response and toxicity. WIREs RNA 2012, 3:469–481. doi: 10.1002/wrna.1111

This article is categorized under:

RNA Structure and Dynamics > RNA Structure, Dynamics, and Chemistry

RNA Structure and Dynamics > Influence of RNA Structure in Biological Systems

RNA Processing > RNA Editing and Modification

RNA in Disease and Development > RNA in Disease
Symmetries and currents of the ideal and unitary Fermi gases
Authors: Bekaert Xavier , Meunier Elisa , Moroz Sergej
Published: February 2012

Abstract

The maximal algebra of symmetries of the free single-particle Schrödinger equation is determined and its relevance for the holographic duality in non-relativistic Fermi systems is investigated. This algebra of symmetries is an infinite dimensional extension of the Schrödinger algebra, it is isomorphic to the Weyl algebra of quantum observables, and it may be interpreted as a non-relativistic higher-spin algebra. The associated infinite collection of Noether currents bilinear in the fermions are derived from their relativistic counterparts via a light-like dimensional reduction. The minimal coupling of these currents to background sources is rewritten in a compact way by making use of Weyl quantisation. Pushing forward the similarities with the holographic correspondence between the minimal higher-spin gravity and the critical O(N ) model, a putative bulk dual of the unitary and the ideal Fermi gases is briefly discussed.
Systematic Review and Meta‐analysis of the Incidence of Incisional Hernia at the Site of Stoma Closure
Authors: Bhangu Aneel , Nepogodiev Dmitri , Futaba Kaori ,   West Midlands Research Collaborative
Published: February 2012

Background

The incidence of incisional hernias at the site of stoma closure is surprisingly unclear. A review of the current literature was undertaken to determine how commonly this complication may occur and to assess the quality of evidence available.

Methods

A systematic review was performed to identify studies reporting the incidence of incisional hernia after closure of an ileostomy or colostomy. Studies including children (<16 years old) and studies in which >10% of the total number were trauma patients were excluded.

Results

Thirty‐four studies provided outcomes for 2,729 closed stomas. Median follow‐up time was 36 months but was only described in seven studies. Closure of loop ileostomies was the most commonly performed procedure (48%). The overall reported hernia rate was 7%, but with a wide range among studies (0–48%). Most studies based their hernia rates on retrospective clinical findings only. A separate analysis of three studies that were specifically designed to assess for stoma site hernias found the clinical hernia rate to be 30% (28/93) and the combined clinical/radiological hernia rate to be 35% (33/93). From 11 studies reporting reoperation rates, 51% of patients who developed a hernia required a surgical repair (34/66). There was a lower risk of hernia following reversal of ileostomy versus colostomy (odds ratio 0.28, 95% confidence interval 0.12–0.65).

Conclusions

One in three patients may develop a hernia after stoma closure, and around half of hernias that are detected require repair. Risk of hernia is greater after colostomy closure than after ileostomy closure. Clinical measures to reduce the development of these hernias warrant consideration.
Partial Small Bowel Resection with Sleeve Gastrectomy Increases Adiponectin Levels and Improves Glucose Homeostasis in Obese Rodents with Type 2 Diabetes
Authors: Kopsombut Gift , Shoulson Rivka , Milone Luca , Korner Judith , Lifante Jean‐Christophe , Sebastian Manu , Inabnet William B.
Published: February 2012

Background

The aim of this study was to examine the effect of small bowel resection with and without sleeve gastrectomy on glucose homeostasis in an obese rodent model of type 2 diabetes.

Methods

Zucker diabetic fatty rats were randomized into three surgical groups: Sham, small bowel resection, and small bowel resection with sleeve gastrectomy (BRSG). Weight and fasting glucose levels were measured at randomization and monitored after surgery. Oral glucose tolerance testing was performed at baseline and 45 days after surgery to assess glucose homeostasis and peptide changes.

Results

At baseline, all animals exhibited impaired glucose tolerance and showed no difference in weight or fasting (area under the curve) AUCglucose. At sacrifice, Sham animals weighed more than BRSG animals (p = 0.047). At day 45, the Sham group experienced a significant increase in AUCglucose compared to baseline (p = 0.02), whereas there was no difference in AUCglucose in either surgical group at any time point: BR (p = 0.58) and BRSG (p = 0.56). Single‐factor ANOVA showed a significant difference in AUCglucose of p = 0.004 between groups postoperatively: Sham (50,745 ± 11,170) versus BR (23,865 ± 432.6) (p = 0.01); Sham versus BRSG (28,710 ± 3188.8) (p = 0.02). There was no difference in plasma insulin, GLP‐1, or adiponectin levels before surgery, although 45 days following surgery adiponectin levels where higher in the BRSG group (p = 0.004).

Conclusions

Partial small bowel resection improved glucose tolerance independent of weight. The combination of small bowel resection and sleeve gastrectomy leads to an increase in adiponectin levels, which may contribute to improved glucose homeostasis.
The effect of dense understory dwarf bamboo (Sasa senanensis) on soil respiration before and after clearcutting of cool temperate deciduous broad‐leaved forest
Authors: Yashiro Yuichiro , Shizu Yoko , Adachi Tatsuharu , Ohtsuka Toshiyuki , Lee Na‐yeon , Iimura Yasuo , Koizumi Hiroshi
Published: February 2012

To evaluate the effect of understory dwarf bamboo (Sasa senanensis) on soil respiration in forest ecosystems, we compared soil respiration rates between four deciduous broad‐leaved forest sites representing two levels of understory Sasa (with and without) and two levels of forest stand age (50‐year‐old stand and 1‐year‐old stand after clearcut). The understory Sasa enhances the soil respiration rate both before and after the clearcutting of deciduous broad‐leaved forest. The Sasa sites had larger total belowground biomass compared with the non‐Sasa sites, which could be attributed to Sasa presence. Our results also suggest that clearcutting decreases temperature‐normalized soil respiration rates (R15) and temperature sensitivity (Q10) in both Sasa and non‐Sasa ecosystems. Clearcutting significantly reduced the fine root biomass of trees and Sasa. The fine roots of trees and Sasa had high specific respiration rates compared with larger roots and rhizomes at Sasa and non‐Sasa sites, respectively. Therefore, we hypothesize that the loss of fine roots after clearcutting is responsible for the reduction in soil respiration rate. A comparison with other studies revealed a positive linear relationship between total (tree and Sasa) fine root biomass and R15, suggesting that fine root biomass controls soil respiration at the landscape scale. The Q10 value is also likely to be related to fine root biomass, although the relationship was not significant. We conclude that understory Sasa increases belowground biomass, especially fine roots, and the spatial variation in soil respiration at the landscape scale.
Spatial and temporal flowering patterns of the monocarpic dwarf bamboo Sasa veitchii var. hirsuta
Authors: Abe Yuhei , Shibata Shozo
Published: February 2012

In order to clarify spatial and temporal patterns in the flowering process of S. veitchii var. hirsuta, the authors investigated the flowering of the species at a regional level in a mountainous area of Kyoto City, and at population/individual culm levels at experimental forest stations within the same municipal region. S. veitchii var. hirsuta flowered in several separate areas spanning ranges between several and more than 10 km north–south and east–west from 2004 to 2007. Sporadic flowering occurred the year before mass flowering. In the mass‐flowering year, 98% of the culms in an S. veitchii var. hirsuta population flowered, and the other 2% or so flowered in the years before and after mass flowering. These results show a spatiotemporal synchronous flowering pattern (with most culms of populations gregariously flowering in a year over a large area) and an asynchronous flowering pattern (with a small percentage of the culms of populations flowering before and after the mass‐flowering year) for S. veitchii var. hirsuta. It was also clarified that the year and scale of mass flowering differ by area, and that mass flowering occurs in individual areas in successive years. The survey performed at the individual culm level revealed that the mean numbers of open florets and attached seeds per culm showed two peaks from April to July, suggesting that S. veitchii var. hirsuta flowering events occur twice a year.
A New Heterogeneous Multidimensional Unfolding Procedure
Authors: Park Joonwook , Rajagopal Priyali , DeSarbo Wayne S.
Published: February 2012

A variety of joint space multidimensional scaling (MDS) methods have been utilized for the spatial analysis of two- or three-way dominance data involving subjects’ preferences, choices, considerations, intentions, etc. so as to provide a parsimonious spatial depiction of the underlying relevant dimensions, attributes, stimuli, and/or subjects’ utility structures in the same joint space representation. We demonstrate that care must be taken with respect to a key assumption in existent joint space MDS models such that all estimated dimensions are utilized by each and every subject in the sample, as this assumption can lead to serious distortions with respect to the derived joint spaces. We develop a new Bayesian dimension selection methodology for the multidimensional unfolding model which accommodates heterogeneity with respect to such dimensional utilization at the individual subject level for the analysis of two or three-way dominance data. A consumer psychology application regarding the preference for Over-the-Counter (OTC) analgesics is provided. We conclude by discussing the practical implications of the results, as well as directions for future research.
A putative myristoylated 2C‐type protein phosphatase, PP2C74, interacts with SnRK1 in Arabidopsis
Authors: Tsugama Daisuke , Liu Shenkui , Takano Tetsuo
Published: February 2012

AKIN10
physically interacts with
PP2C74
by pull down (
View interaction
)
Synthetic constructs in/for the environment: Managing the interplay between natural and engineered Biology
Authors: Schmidt Markus , de Lorenzo Víctor
Published: February 2012

The plausible release of deeply engineered or even entirely synthetic/artificial microorganisms raises the issue of their intentional (e.g. bioremediation) or accidental interaction with the Environment. Containment systems designed in the 1980s–1990s for limiting the spread of genetically engineered bacteria and their recombinant traits are still applicable to contemporary Synthetic Biology constructs. Yet, the ease of DNA synthesis and the uncertainty on how non‐natural properties and strains could interplay with the existing biological word poses yet again the challenge of designing safe and efficacious firewalls to curtail possible interactions. Such barriers may include xeno‐nucleic acids (XNAs) instead of DNA as information‐bearing molecules, rewriting the genetic code to make it non‐understandable by the existing gene expression machineries, and/or making growth dependent on xenobiotic chemicals.
Global gray matter changes in posterior cortical atrophy: A serial imaging study
Authors: Lehmann Manja , Barnes Josephine , Ridgway Gerard R. , Ryan Natalie S. , Warrington Elizabeth K. , Crutch Sebastian J. , Fox Nick C.
Published: February 2012

Background

Posterior cortical atrophy (PCA) is a neurodegenerative condition predominantly associated with Alzheimer's disease (AD) pathology. Cross‐sectional imaging studies have shown different atrophy patterns in PCA patients compared with typical amnestic Alzheimer's disease (tAD) patients, with greatest atrophy commonly found in posterior regions in the PCA group, whereas in the tAD group, atrophy is most prominent in medial temporal lobe regions. However, differential longitudinal atrophy patterns are not well understood.

Methods

This study assessed longitudinal changes in brain and gray matter volumes in 17 PCA patients, 16 tAD patients, and 18 healthy control subjects. Both patient groups had symptom durations of approximately 5 years.

Results

Progressive gray matter losses in both PCA and tAD patients were relatively widespread throughout the cortex, compared with control subjects, and were not confined to areas related to initial symptomatology. A multivariate classification analysis revealed a statistically significant group separation between PCA and tAD patients, with 72.7% accuracy (P < .01).

Conclusion

Progression from an initially focal presentation to a more global pattern suggests that these different clinical presentations of AD might converge pathologically over time.
Evolution of the central Alpine-Himalayan belt in the Late Cenozoic
Authors: Trifonov V.G. , Ivanova T.P. , Bachmanov D.M.
Published: February 2012

The Late Cenozoic geodynamics of the Alpine-Himalayan belt comprised the collision between continental-lithosphere plates and blocks and the effect of the Neo-Tethyan active residual asthenosphere, which reached the northern margin of the belt after the ocean had closed. From the late Eocene to the early Pliocene, strong deformation, lateral migrations of flaked plates, metamorphism, and magmatism (they all consolidated the crust) took place in the lithosphere with the participation of mobile asthenospheric components. In the Pliocene–Quaternary, the asthenosphere beneath the consolidated crust partly replaced the dense mantle lithosphere with remaining paleoocean mafic rocks, which subducted into the mantle. Phase transformations and deformations in the subducting metamafic slabs caused mantle earthquakes. The less compact metamafic rocks experienced metamorphic weakening under the effect of the asthenosphere and incorporated into the Earth’s crust. The upper-mantle and lower-crust weakening led to a drastic intensification of uplifting and the formation of mountain ranges. Recent volcanism is also attributed to the activity of the Neo-Tethyan asthenosphere.
Djerfisherite in xenoliths of sheared peridotite in the Udachnaya-East pipe (Yakutia): origin and relationship with kimberlitic magmatism
Authors: Sharygin I.S. , Golovin A.V. , Pokhilenko N.P.
Published: February 2012

Djerfisherite, a Cl-bearing potassium sulfide (K6Na(Fe,Ni,Cu)24S26Cl), is a widespread accessory mineral in kimberlite-hosted mantle xenoliths. Nevertheless, the origin of this sulfide in nodules remains disputable. It is usually attributed to the replacement of primary Fe–Ni–Cu sulfides when xenoliths interact with a K-and Cl-enriched hypothetical melt/fluid. The paper is devoted to a detailed study of the composition and morphology of djerfisherite from a representative collection (22 samples) of the deepest mantle xenoliths—sheared garnet peridotite, taken from the Udachnaya-East kimberlite pipe (Yakutia). Four types of djerfisherite were distinguished in the mantle rocks on the basis of morphology, spatial distribution, and relationships with the rock-forming and accessory minerals in the nodules. Type 1 was found in the rims of polysulfide inclusions in the rock-forming minerals of the xenoliths; there, it was younger than the primary sulfide assemblage pyrrhotite + pentlandite ± chalcopyrite. Type 2 formed rims around large polysulfide segregations (pyrrhotite+ pentlandite) in the xenolith interstices. Type 3 formed individual grains in the xenolith interstices together with other sulfides, silicates, oxides, phosphates, and carbonates. Type 4 was present as a daughter phase in the secondary melt inclusions which occurred in healed cracks in the rock-forming minerals of the xenoliths. Along with djerfisherite, the inclusions contained silicates, oxides, phosphates, carbonates, alkaline sulfates, chlorides, and sulfides. The results indicate that djerfisherite from the xenoliths is consanguine with kimberlite. Djerfisherite both in the sheared-peridotite xenoliths from the Udachnaya-East pipe and in different xenoliths from other kimberlite pipes worldwide formed owing to the interaction between the nodules and kimberlitic melts. Djerfisherite forming individual grains in the melt inclusions and xenolith interstices crystallized directly from the infiltrating kimberlitic melt. Djerfisherite bounding the primary Fe–Ni ± Cu sulfides formed by their replacement as a result of a reaction with the kimberlitic melt.
The geochemistry and isotopic age of eclogites from the Belomorian Belt (Kola Peninsula): evidence for subducted Archean oceanic crust
Authors: Shchipansky A.A. , Khodorevskaya L.I. , Slabunov A.I.
Published: February 2012

We present results of geochemical studies and isotope dating of eclogites and associated rocks from the Kuru-Vaara quarry, Belomorian Belt, Northeastern Baltic Shield. The southern and northern eclogites are similar in geochemical features. Their protoliths were primitive, mainly high-Mg basalts of oceanic affinity derived from a primitive mantle source rather than from a depleted mantle source characteristic of modern MORB. The post-eclogitic intrusive rocks show obvious evidence for crustal contamination. The eclogite-hosting tonalitetrondhjemite-granodiorite (TTG) gneisses form a coherent series including high-Al and low-Al varieties. The trace element data show that the TTG series formed through the hydrous partial melting of the southern eclogites in the presence of garnet and amphibole in the field of the rutile stability (>15 kbar). Zircons from the southern eclogites exhibit features of their strong re-equilibration by coupled dissolution–reprecipitation processes but have locally preserved patches with a primary magmatic zoning. The geochemistry of the patches points to the oceanic provenance of protolithic zircons; their isotope dating (SHRIMP-II) yielded a concordant age of 2821 ± 21 Ma. Zircons from the trondhjemite gneiss with geochemical features of Archean adakite were dated at 2805 ± 11 Ma, which suggests the syneclogitic facies origin of the TTG melts. The concordant age of high-pressure zircons from the northern eclogites is 2722 ± 21 Ma, close to the age of the earlier described Gridino eclogites. The overview of the isotopically dated eclogite bodies show the presence of at least three temporally distinct groups of eclogites in the Belomorian Belt, ∼2.86–2.87, ∼2.82–2.80, and ∼2.72 Ga, which is in a good accordance with the known isotopic ages for major crust-forming events in the belt. This, in turn, implies a close genetic relationship between the eclogites and the TTG origin, which might be consistent with the model of the short intermitted events of subduction of the thickened Archean oceanic crust. The presence of HP/UHP eclogites of different ages and the structural style of the Belomorian Belt permit it to be assigned to megamélange belts.
The impact of technogenic factors on the seismicity of the Kuznetsk Basin region and Lake Baikal
Authors: Bryksin A.A. , Seleznev V.S.
Published: February 2012

Using the materials from the catalogue of seismic events in the Siberian region, we estimated the impact of man’s activity on natural seismicity. Local man’s intervention into natural processes has been studied by the examples of commercial explosions during the quarry mineral mining in the Kuznetsk Basin and the exploitation of the railroad site along the shore of Lake Baikal. Seismic emission is shown to change with time under the impact of powerful monochromatic vibrators on the environment.
On the nature of temperature variations in borehole kun-1 (Kunashir Island)
Authors: Demezhko D.Yu. , Yurkov A.K. , Utkin V.I. , Klimshin A.V.
Published: February 2012

The study presents the result of continuous temperature monitoring in a 300 m deep borehole located on the Pacific coast of the Kunashir Island. Temperature variations at of 20–240 m depths with periods from a few tens of minutes to a few tens of days and amplitudes in the order of thousandths to tenths of degree are found to result from three main causes: tidal variations of groundwater level in the borehole, natural convection in the borehole, and nonperiodic and spatially heterogeneous changes of the pore pressure resulting in the appearance of an anomalous subsurface fluid regime and generating crossflow between the different aquifers through the annular space. Joint analysis of temperature and seismic data revealed that shallow-focus (up to 30 km) earthquakes with M > 5 occurred southeast of the seismic station created more expressed temperature response at 240 m depth. This response has the form of a 0.05–0.3 K temperature drop, which precedes a seismic event within a period of a few hours to a few days. Tidal analysis of borehole temperature measurements can be used to calculate the strain sensitivity and the method of borehole temperature monitoring can be used to investigate the tectonic regime of the Earth’s crust.
Clay mineral variations in Holocene terrestrial sediments from the Indus Basin
Authors: Alizai Anwar , Hillier Stephen , Clift Peter D. , Giosan Liviu , Hurst Andrew , VanLaningham Sam , Macklin Mark
Published: February 2012

We employed X-ray diffraction methods to quantify clay mineral assemblages in the Indus Delta and flood plains since ~ 14 ka, spanning a period of strong climatic change. Assemblages are dominated by smectite and illite, with minor chlorite and kaolinite. Delta sediments integrate clays from across the basin and show increasing smectite input between 13 and 7.5 ka, indicating stronger chemical weathering as the summer monsoon intensified. Changes in clay mineralogy postdate changes in climate by 5–3 ka, reflecting the time needed for new clay minerals to form and be transported to the delta. Samples from the flood plains in Punjab show evidence for increased chemical weathering towards the top of the sections (6–≪ 4 ka), counter to the trend in the delta, at a time of monsoon weakening. Clay mineral assemblages within sandy flood-plain sediment have higher smectite/(illite + chlorite) values than interbedded mudstones, suggestive of either stronger weathering or more sediment reworking since the Mid Holocene. We show that marine records are not always good proxies for weathering across the entire flood plain. Nonetheless, the delta record likely represents the most reliable record of basin-wide weathering response to climate change.
All bent out of shape: buckling of sheared fluid layers
Authors: Ribe Neil M.
Published: February 2012

Buckling instabilities of thin sheets or plates of viscous fluid occur in situations ranging from food and polymer processing to geology. Slim, Teichman & Mahadevan (J. Fluid Mech., this issue, vol. 694, 2012, pp. 5–28) study numerically the buckling of a sheared viscous plate floating on a denser fluid using three approaches: a classical ‘thin viscous plate’ model; full numerical solution of the three-dimensional Stokes equations; and a novel ‘advection-augmented’ thin-plate model that accounts (in an asymptotically inconsistent way) for the advection of perturbations by the background shear flow. The advection-augmented thin-plate model is markedly superior to the classical one in its ability to reproduce the predictions of the Stokes solution, illustrating the utility of judicious violations of asymptotic consistency in fluid-mechanical models.
Anthropology, standardization and measurement: Rudolf Martin and anthropometric photography
Authors: MORRIS-REICH AMOS
Published: February 2012

Recent scholarship on the history of German anthropology has tended to describe its trajectory between 1900 and the Nazi period as characterized by a paradigmatic shift from the liberal to the anti-humanistic. This article reconstructs key moments in the history of anthropometric photography between 1900 and 1925, paying particular attention to the role of the influential liberal anthropologist Rudolf Martin (1864–1925) in the standardization of anthropological method and technique. It is shown that Rudolf Martin's primary significance was social and institutional. The article reconstructs key stages in Martin's writing on and uses of photography and analyses the peculiar form of scientific debate surrounding the development of anthropometric photography, which centred on local and practical questions. Against the political backdrop of German colonialism in Africa and studies of prisoners of war during the First World War, two key tensions in this history surface: between anthropological method and its politicization, and between the international scientific ethos and nationalist impulses. By adopting a practical–epistemic perspective, the article also destabilizes the conventional differentiation between the German liberal and anti-humanist anthropological traditions. Finally, the article suggests that there is a certain historical irony in the fact that the liberal Martin was central in the process that endowed physical anthropology with prestige precisely in the period when major parts of German society increasingly came to view ‘race’ as offering powerful, scientific answers to social and political questions.
On the convergence of Diophantine Dirichlet series
Authors: Rivoal T.
Published: February 2012

We study various Dirichlet series of the form ∑n≥1f(πnα)/ns, where α is an irrational number andf(x)is a trigonometric function like cot(x), 1/sin(x) or 1/sin2(x). The convergence is slow and strongly depends on the Diophantine properties of α. We provide necessary and sufficient convergence conditions using the continued fraction of α. We also show that any one of our series is equal to a related series, which converges much faster, defined in term of iterations of the continued fraction operator α↦{1/α}.
Nil algebras with restricted growth
Authors: Lenagan T. H. , Smoktunowicz Agata , Young Alexander A.
Published: February 2012

It is shown that over an arbitrary countable field there exists a finitely generated algebra that is nil, infinite dimensional and has Gelfand–Kirillov dimension at most 3.
Exploring endocrine regulation of sea urchin reproductive biology: effects of 17ß-oestradiol
Authors: Sugni Michela , Motta Daphne , Tremolada Paolo , Candia Carnevali Maria Daniela
Published: February 2012

Although several authors have suggested a plausible involvement of steroids in the reproductive biology of echinoderms, their definitive role is still poorly understood. In this paper we focused on oestradiol (E2), whose presence and variations were previously revealed in different echinoderm tissues. The aim of this investigation was to provide further information on the scarcely known role of this hormone in the reproductive biology of sea urchins. We injected two different concentrations (5 ng ml−1and 50 ng ml−1) of 17ß-oestradiol into specimens of the commonParacentrotus lividusfor 10 weeks. The E2treatment did not influence the maturation stage of the gonads and the development of the gametes; it caused a slight decrease in the gonad index and an increase in lipid content. Our present results suggest that E2could have a function different from that reported for vertebrates and suggested for other echinoderms such as asteroids.
The infrapopulation dynamics of trypanosomes in red-spotted newts
Authors: Mock Beverly A. , Gill P. E.
Published: February 2012

The parasitic protozoan Trypanosoma diemyctyli has a life-cycle that involves a vertebrate host, the red-spotted newt Notophthalmus viridescens, and an invertebrate host, the amphibian leech Batrachobdella picta. A study of the distribution and dynamics of this parasite in newts of known adult age and history of breeding in montane ponds in Virginia revealed a pattern of: (1) moderate prevalences of infection in post-metamorphic juvenile and adult stages, (2) rapid increases in numbers of trypanosomes in newts during their first year of maturity, (3) significant differences in the numbers of trypanosomes in male and female newts in mid-summer, (4) sustained high levels of infection in the first two years of newt adulthood, (5) significantly lower levels of infection in newts by the fourth and subsequent years of adulthood and (6) annual oscillations in the intensity of infection in older adult newts from spring and autumn lows to mid-summer peak levels. Newts with a history of skipping breeding seasons had higher levels of infection than those newts which returned to the pond for every breeding season. Newts brought to the laboratory and maintained under leech-free conditions failed to develop infection levels comparable to those in the field. The dynamics of infrapopulation sizes of trypanosomes in newts depend on multi plication rates of the trypanosomes, variable transmission rates from the invertebrate host and the development of resistance in older adult newts.
Brain volume reductions in medication-naive patients with schizophrenia in relation to intelligence quotient
Authors: Rais M. , Cahn W. , Schnack H. G. , Hulshoff Pol H. E. , Kahn R. S. , van Haren N. E. M.
Published: February 2012

Background

Global brain abnormalities such as brain volume loss and grey- and white-matter deficits are consistently reported in first-episode schizophrenia patients and may already be detectable in the very early stages of the illness. Whether these changes are dependent on medication use or related to intelligence quotient (IQ) is still debated.

Method

Magnetic resonance imaging scans were obtained for 20 medication-naive patients with first-episode schizophrenia and 26 matched healthy subjects. Volume measures of total brain grey and white matter, third and lateral ventricles and cortical thickness/surface were obtained. Differences between the groups were investigated, taking into account the effect of intelligence.

Results

Medication-naive patients showed statistically significant reductions in whole-brain volume and cerebral grey- and white-matter volume together with lateral ventricle enlargement compared to healthy subjects. IQ was significantly lower in patients compared to controls and was positively associated with brain and white-matter volume in the whole group. No significant differences in cortical thickness were found between the groups but medication-naive patients had a significantly smaller surface in the left superior temporal pole, Heschl's gyrus and insula compared to controls.

Conclusions

Our findings suggest that brain volume loss is present at illness onset, and can be explained by the reduced surface of the temporal and insular cortex. These abnormalities are not related to medication, but IQ.
Synthetic biology in space: considering the broad societal and ethical implications
Authors: Race Margaret S. , Moses Jacob , McKay Christopher , Venkateswaran Kasthuri J.
Published: February 2012

Although the field of synthetic biology is still in its infancy, there are expectations for great advances in the coming decades, both on Earth and potentially in space. Promising applications for long duration space missions include a variety of biologically engineered products and biologically aided processes and technologies, which will undoubtedly be scrutinized for risks and benefits in the broad context of ethical, legal and social realms. By comparing and contrasting features of Earth-based and space-applied synthetic biology, it is possible to identify the likely similarities and differences, and to identify possible challenges ahead for space applications that will require additional research, both in the short and long terms. Using an analytical framework associated with synthetic biology and new technologies on Earth, this paper analyses the kinds of issues and concerns ahead, and identifies those areas where space applications may require additional examination. In general, while Earth- and space-based synthetic biology share many commonalities, space applications have additional challenges such as those raised by space microbiology and environmental factors, legal complications, planetary protection, lack of decision-making infrastructure(s), long duration human missions, terraforming and the possible discovery of extraterrestrial (ET) life. For synthetic biology, the way forward offers many exciting opportunities, but is not without legitimate concerns – for life, environments and society, both on Earth and beyond.
Nicht-suizidale Selbstverletzung als eigenständige Diagnose
Authors: Plener Paul L. , Kapusta Nestor D. , Kölch Michael G. , Kaess Michael , Brunner Romuald
Published: February 2012

Selbstverletzendes Verhalten stellt in den Klassifikationssystemen DSM-IV-TR und ICD-10 ein Symptom der Borderline Persönlichkeitsstörung (BPS) dar. In den letzten Jahren konnte empirisch gezeigt werden, dass selbstverletzendes Verhalten auch unabhängig von einer BPS etwa bei depressiven Störungen oder auch bei Jugendlichen ohne klassifizierbare Psychopathologie auftritt. Die wissenschaftliche Diskussion um eine eigenständige diagnostische Kriterienbildung für dieses Phänomen führte nun zu einem Vorschlag zur Neuaufnahme einer Diagnose mit der Bezeichnung «Nicht-suizidale Selbstverletzung» in das sich in Entwicklung befindliche DSM-5. Vor dem Hintergrund aktueller Untersuchungen zur Häufigkeit selbstverletzenden Verhaltens bei Jugendlichen in Deutschland kann davon ausgegangen werden, dass ca. 4 % der Jugendlichen im mittleren und späten Adoleszenzalter das Kriterium A (mindestens fünf selbstverletzende Handlungen in den vorausgegangenen 12 Monaten) der vorgeschlagenen Störung im DSM-5 erfüllen. Eine auf empirische Untersuchungen basierende Klassifikation selbstverletzender Handlungen wird sowohl für die Forschung, wie auch für die Behandlung und zur Implementierung von Präventionsmaßnahmen hilfreich sein.
Creep of partially molten fine‐grained gabbro under dry conditions
Authors: Zhou Yongsheng , Rybacki Erik , Wirth Richard , He Changrong , Dresen Georg
Published: February 2012

Natural fine‐grained gabbro was deformed in a Paterson deformation apparatus to evaluate the flow strength of lower crustal rocks containing partial melt. We performed 94 creep stepping tests on seven samples at 300 MPa confining pressure, temperatures between 950°C and 1150°C, and axial stresses of 25–510 MPa, resulting in strain rates between 2.3 × 10−4 and 6.7 × 10−8 s−1. Water content of samples predried at 1000°C at 1 atm was about 0.035 wt % H2O. The drying process induced partial melting of the starting material of ∼1 vol % Si‐poor and Fe‐rich melt at grain boundaries, which increased further up to ∼2 vol % during creep tests. Creep tests reveal strain rates increasing with duration of the tests related to increasing melt content present in the samples. Microstructural observations of deformed samples show melt in triple junctions and melt films contained in grain boundaries. The observed microstructures indicate that the samples were deformed in the dislocation creep regime. Dislocation walls are present in pyroxene and plagioclase grains. Very fine grained (about 10 μm) pyroxene and olivine were produced by mineral reactions and dynamic recrystallization at temperatures >1000°C. Melt fraction ϕ of creep test samples and annealed samples increases linearly with logarithm of time (log(t)), suggesting that strain rate enhancement by partial melting can be described by an exponential function of melt fraction with an exponent coefficient of 128. After applying a correction for the time‐dependent increase of melt content the data were fitted to a power law creep equation, resulting in a stress exponent of n = 4.0 ± 0.3, an activation energy of Q = 644 ± 75 kJ mol−1, and a preexponential factor of A = 1010.3 ± 0.4 MPan s−1 for dry gabbro that contains ∼1 vol % melt. The flow law for gabbro from this study is compared to published flow law parameters of basaltic composition rocks.
Spatial migration of earthquakes within seismic clusters in Southern California: Evidence for fluid diffusion
Authors: Chen X. , Shearer P. M. , Abercrombie R. E.
Published: February 2012

Seismicity within many earthquake swarms is observed to migrate slowly with time, which may reflect event triggering due to slow fault slip or fluid flow. We search for this behavior in Southern California by applying a weighted least squares method to quantify event migration within 69 previously observed seismicity bursts. We obtain best‐fitting migration directions and velocities, and compute a statistical migration significancesm for each burst using a bootstrap resampling method. We define 37 bursts with sm ≥ 0.8 as the migration group, and 32 bursts with sm < 0.8 as the non‐migration group. To explore differences between the two groups, for each burst we compute effective stress drop (Δσquasi, the ratio between total moment and radius), the skew of the moment release time series (μ), the timing of the largest event (tmax), and the distance separation between the first half and second half of the sequence (ds). As expected, the migration group features larger ds and lower Δσquasi, consistent with higher migration significance. It also features lower μ and higher tmax, similar to observations from swarms in the Salton Trough, while the non‐migration group is more similar to main shock‐aftershock sequences. To explore possible fluid involvement, we model the migration behavior with the fluid diffusion equation, and identify 18 bursts with diffusion coefficients ranging from 0.01 to 0.8 m2/s, with the majority below 0.16 m2/s. The obtained diffusion coefficients and migration behavior are similar to the Reservoir‐induced seismicity beneath the Açu reservoir in Brazil. The majority of normal faulting events are associated with these 18 bursts, while the non‐migration group has the most reverse faulting events, indicating a possible link between sequence type and focal mechanism.
Impact of Siberian coastal polynyas on shelf‐derived Arctic Ocean halocline waters
Authors: Bauch Dorothea , Hölemann Jens A. , Dmitrenko Igor A. , Janout Markus A. , Nikulina Anna , Kirillov Sergey A. , Krumpen Thomas , Kassens Heidemarie , Timokhov Leo
Published: February 2012

Hydrographic and stable oxygen isotope (H218O/H216O) sampling was carried out within the West New Siberian (WNS) coastal polynyas in the southern Laptev Sea in late winters 2008 and 2009. The impact of sea ice formation on the water column was quantified by a salinity/δ18O mass balance. Several stations had vertically homogeneous physical properties in April/May 2008 and featured polynya‐formed local bottom water with elevated signals of brine released during sea ice formation and elevated fractions of river water. The polynya‐formed bottom water was fresher than surrounding bottom waters. At other stations, salinity/δ18O correlation showed well‐defined mixing lines for bottom and surface layers. In March–April 2009, surface waters were strongly influenced by Lena River water, and local polynya activity with elevated brine signals reached to intermediate depth but did not penetrate the bottom layer in the highly stratified water column. Inventory values of sea ice formation were comparable in both years, but freshwater distributions from the preceding summers were different. Therefore, the observed difference in the impact of polynya activity on the water column is not primarily controlled by the amount of sea ice formed during winter but by preconditioning from the preceding summer. Only in years when the river plume is mostly absent in the polynya region is stratification weak and allows winter sea ice formation to reach the bottom layer. Thus summer stratification controls the influence of local polynya water on the shelf's bottom hydrography and, as bottom water is exported, impacts on the source water of shelf‐derived halocline waters.