bluuebunny/crossref_metadata_2025 huggingface dataset:
Detrital zircon and isotopic constraints on the crustal architecture and tectonic evolution of the northeastern Pamir
Authors: Robinson Alexander C. , Ducea Mihai , Lapen Thomas J.
Published: March 2012

New detrital zircon and isotopic (Nd and Sr) analyses from the eastern Pamir provide information on the depositional age and tectonic terrane affiliation of regional metamorphic terranes. Our results show the following. First, detrital zircon analyses from metasedimentary units along the Kongur Shan extensional system dominantly yield Triassic maximum depositional ages, with a similar age distribution to the Tibetan Songpan‐Ganzi terrane. Further, zircon analyses from quartzofeldspathic gneisses in the core of the Muztaghata massif show the protoliths are Triassic granites. These units are interpreted to be part of the Permian‐Triassic Karakul‐Mazar arc‐accretionary complex terrane. Second, εNd(0) compositions of Triassic granites overlap with other metasedimentary units not analyzed for detrital zircons and are also interpreted to be part of the Karakul‐Mazar terrane. Third, schists in the Sares‐Muztaghata gneiss dome structurally above Triassic orthogneisses yield an Ordovician maximum depositional age with a distinct detrital age distribution similar to the Tibetan Qiangtang terrane and are interpreted to be part of the Central Pamir terrane. Finally, Triassic and Ordovician schists along the Muztaghata massif record an Early Jurassic metamorphic event interpreted to date south‐directed subduction of the Karakul‐Mazar terrane beneath the Central Pamir during final closure of the Paleo‐Tethys. These results, integrated with previously published results and field relations, reveal a complex Mesozoic to Cenozoic interleaving of tectonic terranes in the eastern Pamir with emplacement of the Karakul Mazar terrane both above and below the Kunlun and Central Pamir terranes to the north and south, respectively.
Flow topology and scalar mixing in spatially heterogeneous flow fields
Authors: de Barros Felipe P. J. , Dentz Marco , Koch Jonas , Nowak Wolfgang
Published: March 2012

Scalar mixing plays a significant role for transport in geophysical flows because it controls dilution and is a main driver for many chemical reactions. Here we study the local scale flow mechanisms that lead to enhanced scalar mixing, and how they impact on the global mixing behavior. Mixing is quantified in terms of the entropy of the scalar distribution. It is shown that the evolution of entropy is directly linked to the flow topology in terms of the Okubo‐Weiss parameter Θ. Dominant shear and stretching deformation (Θ > 0) leads to a strong increase of local mixing strength, while dominant vorticity (Θ < 0) has only a minor impact. This allows to delineate regions of increased scalar mixing potential by mapping out the spatial distribution of Θ(x), and to relate global scalar mixing to an areal averaged effective Okubo‐Weiss measure.
The thermal threshold of the Atlantic meridional overturning circulation and its control by wind stress forcing during glacial climate
Authors: Oka A. , Hasumi H. , Abe‐Ouchi A.
Published: March 2012

Paleo proxy data suggest that the Atlantic meridional overturning circulation (AMOC) was shallower and weaker at the Last Glacial Maximum (LGM) than at present. In this study, we have identified the existence of a thermal threshold of the AMOC which may explain why many coupled climate models fail to simulate the weaker AMOC during the LGM. By using results obtained from a coupled climate model and conducting sensitivity simulations with an ocean general circulation model, we found that the sudden transition from the present‐day AMOC to the weaker glacial AMOC occurs when we gradually change the degree of surface cooling from present‐day to glacial conditions. This result is related to response of deep convection in the northern North Atlantic Ocean; moderate cooling enhances deep convection whereas sufficient cooling results in total covering of sea ice there and suppression of deep convection. The findings indicate the existence of a thermal threshold controlling the AMOC, where the present‐day‐type AMOC suddenly shifts to the weaker glacial AMOC once the surface cooling exceeds this threshold. We also demonstrate that wind stress forcing plays a critical role in controlling the value of the thermal threshold. Our study suggests that slight differences in the degree of surface cooling or wind stress forcing for LGM simulations could lead to the very different response of the AMOC during the LGM as reported in previous LGM simulations.
The Development, Past Achievements, and Future Directions of Brain PET
Authors: Jones Terry , Rabiner Eugenii A
Published: March 2012

The early developments of brain positron emission tomography (PET), including the methodological advances that have driven progress, are outlined. The considerable past achievements of brain PET have been summarized in collaboration with contributing experts in specific clinical applications including cerebrovascular disease, movement disorders, dementia, epilepsy, schizophrenia, addiction, depression and anxiety, brain tumors, drug development, and the normal healthy brain. Despite a history of improving methodology and considerable achievements, brain PET research activity is not growing and appears to have diminished. Assessments of the reasons for decline are presented and strategies proposed for reinvigorating brain PET research. Central to this is widening the access to advanced PET procedures through the introduction of lower cost cyclotron and radiochemistry technologies. The support and expertize of the existing major PET centers, and the recruitment of new biologists, bio-mathematicians and chemists to the field would be important for such a revival. New future applications need to be identified, the scope of targets imaged broadened, and the developed expertize exploited in other areas of medical research. Such reinvigoration of the field would enable PET to continue making significant contributions to advance the understanding of the normal and diseased brain and support the development of advanced treatments.
Ischemic Neuroprotection by TRPV1 Receptor-Induced Hypothermia
Authors: Muzzi Mirko , Felici Roberta , Cavone Leonardo , Gerace Elisabetta , Minassi Alberto , Appendino Giovanni , Moroni Flavio , Chiarugi Alberto
Published: March 2012

Although treatment of stroke patients with mild hypothermia is a promising therapeutic approach, chemicals inducing prompt and safe reduction of body temperature are an unmet need. We measured the effects of the transient receptor potential vanilloid-1 (TRPV1) agonist rinvanil on thermoregulation and ischemic brain injury in mice. Intraperitoneal or intracerebroventricular injection of rinvanil induces mild hypothermia that is prevented by the receptor antagonist capsazepine. Both intraischemic and postischemic treatments provide permanent neuroprotection in animals subjected to transient middle cerebral artery occlusion (MCAo), an effect lost in mice artificially kept normothermic. Data indicate that TRPV1 receptor agonists are promising candidates for hypothermic treatment of stroke.
Recombination modulates how selection affects linked sites in Drosophila
Authors: McGaugh Suzanne , Smukowski Caiti , Manzano-Winkler Brenda , Himmel Tiffany , Noor Mohamed
Published: March 2012

One of the most influential observations in molecular evolution has been a strong association between regional recombination rate and amount of nucleotide polymorphism in those genomic regions, interpreted as evidence for ubiquitous natural selection. The alternative explanation, that recombination is mutagenic, has been rejected by the absence of a similar association between regional recombination rate and nucleotide divergence between species. However, many recent studies show that recombination rates are often very different even in closely related species, questioning whether an association between recombination rate and divergence between species has been tested satisfactorily. To circumvent this problem, we directly surveyed recombination across approximately 43% of the D. pseudoobscura physical genome in two separate recombination maps, and 31.3% of the D. miranda physical genome, and we identified both global and local differences in recombination rate between these two closely related species. Using only regions with conserved recombination rates between and within species and accounting for multiple covariates, our data support the conclusion that recombination is positively related to diversity because recombination modulates hitchhiking in the genome. Finally, our data show that diversity around nonsynonymous substitutions is recovered at closer distances in areas of higher recombination than in areas of lower recombination — empirically demonstrating that recombination rate can limit the size and severity of potential selective sweeps.
Mechanism of adaptability for the nano-structured TiAlCrSiYN-based hard physical vapor deposition coatings under extreme frictional conditions
Authors: Fox-Rabinovich G. S. , Endrino J. L. , Aguirre M. H. , Beake B. D. , Veldhuis S. C. , Kovalev A. I. , Gershman I. S. , Yamamoto K. , Losset Y. , Wainstein D. L. , Rashkovskiy A.
Published: March 2012

Recently, a family of hard mono- and multilayer TiAlCrSiYN-based coatings have been introduced that exhibit adaptive behavior under extreme tribological conditions (in particular during dry ultrahigh speed machining of hardened tool steels). The major feature of these coatings is the formation of the tribo-films on the friction surface which possess high protective ability under operating temperatures of 1000 °C and above. These tribo-films are generated as a result of a self-organization process during friction. But the mechanism how these films affect adaptability of the hard coating is still an open question. The major mechanism proposed in this paper is associated with a strong gradient of temperatures within the layer of nano-scaled tribo-films. This trend was outlined by the performed thermodynamic analysis of friction phenomena combined with the developing of a numerical model of heat transfer within cutting zone based on the finite element method. The results of the theoretical studies show that the major physical-chemical processes during cutting are mostly concentrated within a layer of the tribo-films. This nano-tribological phenomenon produces beneficial heat distribution at the chip/tool interface which controls the tool life and wear behavior.Results of x-ray photoelectron spectroscopy studies indicate enhanced formation of protective sapphire- and mullite-like tribo-films on the friction surface of the multilayer TiAlCrSiYN/TiAlCrN coating. Comprehensive investigations of the structure and phase transformation within the coating layer under operation have been performed, using high resolution transmission electron microscopy, synchrotron radiation technique: x-ray absorption near-edge structure and XRD methods.The data obtained show that the tribo-films efficiently perform their thermal barrier functions preventing heat to penetrate into the body of coated cutting tool. Due to this the surface damaging process as well as non-beneficial phase transformation (formation of AlN hex phase) drastically diminishes within the layer of the adaptive coating. Micro-mechanical properties measurements performed at room and elevated temperatures show that the hardness of the multilayer TiAlCrSiYN/TiAlCrN coating appears stable to 500 °C and then drops a little at 600 °C but still remains high. It means that if the surface tribo-films can reduce actual temperature down to this level the coating underneath is able to efficiently withstand heavy loads under operation.
The optical activity of carvone: A theoretical and experimental investigation
Authors: Lambert Jason , Compton R. N. , Crawford T. Daniel
Published: March 2012

The optical rotatory dispersion (ORD) and circular dichroism of the conformationally flexible carvone molecule has been investigated in 17 solvents and compared with results from calculations for the “free” (gas phase) molecule. The G3 method was used to determine the relative energies of the six conformers. The optical rotation of (R)-(−)-carvone at 589 nm was calculated using coupled cluster and density functional methods, including temperature-dependent vibrational corrections. Vibrational corrections are significant and are primarily associated with normal modes involving the stereogenic carbon atom and the carbonyl group, whose n → π* excitation plays a significant role in the chiroptical response of carvone. Without the inclusion of vibrational corrections the optical rotation calculated with CCSD and DFT has the opposite sign of experimental data. Calculations of optical rotation performed in solution using the polarizable continuum model were also opposite in sign when compared to that of the experiment.
LiFePO4 – 3D carbon nanofiber composites as cathode materials for Li-ions batteries
Authors: Dimesso L. , Spanheimer C. , Jaegermann W. , Zhang Y. , Yarin A. L.
Published: March 2012

The characterization of carbon nanofiber 3D nonwovens, prepared by electrospinning process, coated with olivine structured lithium iron phosphate is reported. The LiFePO4 as cathode material for lithium ion batteries was prepared by a Pechini-assisted reversed polyol process. The coating has been successfully performed on carbon nanofiber 3D nonwovens by soaking in aqueous solution containing lithium, iron salts and phosphates at 70 °C for 2−4 h. After drying-out, the composites were annealed at 600 °C for 5 h under nitrogen. The surface investigation of the prepared composites showed a uniform coating of the carbon nonwoven nanofibers as well as the formation of cauliflower-like crystalline structures which are uniformly distributed all over the surface area of the carbon nanofibers. The electrochemical measurements on the composites showed good performances delivering a discharge specific capacity of 156 mAhg− 1 at a discharging rate of C/25 and 152 mAhg− 1 at a discharging rate of C/10 at room temperature.
Unusual intermediate spin Fe3+ ion in antiferromagnetic Li3FeN2
Authors: Ming Xing , Wang Xiao-Lan , Du Fei , Han Bing , Wang Chun-Zhong , Chen Gang
Published: March 2012

The electronic configuration, spin-ordering state, and electronic structure of ternary nitride Li3FeN2 are revisited by comprehensive first-principles density functional calculations. The ferromagnetic (FM) and antiferromagnetic (AFM1) solutions show low spin (S = 1/2) states with FM intra-chain coupling interactions, whereas the AFM2 and AFM3 solutions display unusual intermediate spin (S = 3/2) states with AFM intra-chain coupling interactions. The insulating AFM solutions with intra-chain AFM coupling interactions are energetically favorable relative to the magnetic ordering states with intra-chain FM coupling interactions, which are in good agreement with experimental results. The spin exchange parameters are deduced by mapping the energies of the magnetic ordering states onto the Heisenberg Hamiltonian. Calculated magnetic coupling parameters indicate that the intra-chain AFM interactions are much stronger than the inter-chain coupling interactions; thus, Li3FeN2 can be described as a one-dimensional AFM spin chain system.
Mapping of hyperthermic tumor cell death in a microchannel under unidirectional heating
Authors: Wang Fen , Li Yuhui , Chen Lei , Chen Dandan , Wu Xiaolei , Wang Hao
Published: March 2012

Hyperthermia can be used as an adjunctive method of chemotherapy, radiotherapy, and gene therapy to improve cancer treatment. In this study, we investigate the hyperthermic cell death of cervix cancer CaSki cells in a microchannel integrated with a directional heating scheme. Heat was applied from the inner end to the outer end of the channel and a temperature distribution from 60 °C to 30 °C was established. A three dimensional (3D) numerical model was conducted for the heat transfer simulation, based on which a simple fitting method was proposed to easily estimate the temperature distribution along the channel. Cell death along the channel was mapped 22 h after the heating treatment by dual fluorescent labeling and phase-contrast microscopy imaging. Upstream, where the temperature is higher than 42 °C, we observe necrotic death, late-stage and early stage apoptotic death in sequence along the channel. Downstream and in the middle of the channel, where the temperature is lower than 42 °C, significant cell detachment was noted. Vigorous detachment was observed even in the non-hyperthermic zone (temperature lower than 37 °C), which we believe is due to the direct effect of the hyperthermic zones (higher than 37 °C). The present work not only gives a vivid map of cell responses under a temperature gradient, but also reveals the potential interactions of the heated tumor cells and non-heated tumor cells, which are seldom investigated in conventional petri-dish experiments.
Two kinds of new integrable decompositions of the Gerdjikov-Ivanov equation
Authors: Yu Jing , He Jingsong , Han Jingwei
Published: March 2012

The Gerdjikov-Ivanov(GI) equation can be given from the first non-trivial flow of the generalized Kaup-Newell equations under a reduction condition. In this paper, we perform binary nonlinearization for the generalized Kaup-Newell equations under two symmetry constraints. By imposing the reduction condition on this nonlinearization, we obtain two kinds of new integrable decompositions of the GI equation.
Finite-dimensional attractors for the Kirchhoff models with critical exponents
Authors: Zhijian Yang
Published: March 2012

The paper studies the existence of the finite-dimensional global attractor and exponential attractor for the dynamical system associated with the Kirchhoff models utt − ∇ · {|∇u|m − 1∇u} − Δut + Δ2u + h(ut) + g(u) = f(x). It proves that for the subcritical and critical cases: \documentclass[12pt]{minimal}\begin{document}$1<m \le \frac{N+2}{(N-2)^+}$\end{document}1<m≤N+2(N−2)+, with N ⩽ 6, the above-mentioned dynamical system possesses in phase spaces X1 a finite-dimensional global attractor and a weak exponential attractor, respectively.
On the geometry of double field theory
Authors: Vaisman Izu
Published: March 2012

Double field theory was developed by theoretical physicists as a way to encompass T-duality. In this paper, we express the basic notions of the theory in differential-geometric invariant terms in the framework of para-Kähler manifolds. We define and study the metric algebroids that possess a bracket which is analogous to the Courant bracket of generalized geometry. We show that a double field gives rise to two canonical connections, whose scalar curvatures can be integrated to obtain actions. Finally, in analogy with Dirac structures, we define and study para-Dirac structures on double manifolds.
X-ray pulse preserving single-shot optical cross-correlation method for improved experimental temporal resolution
Authors: Beye M. , Krupin O. , Hays G. , Reid A. H. , Rupp D. , Jong S. de , Lee S. , Lee W.-S. , Chuang Y.-D. , Coffee R. , Cryan J. P. , Glownia J. M. , Föhlisch A. , Holmes M. R. , Fry A. R. , White W. E. , Bostedt C. , Scherz A. O. , Durr H. A. , Schlotter W. F.
Published: March 2012

We measured the relative arrival time between an optical pulse and a soft x-ray pulse from a free-electron laser. This femtosecond cross-correlation measurement was achieved by observing the change in optical reflectivity induced through the absorption of a fraction of the x-ray pulse. The main x-ray pulse energy remained available for an independent pump-probe experiment where the sample may be opaque to soft x-rays. The method was employed to correct the two-pulse delay data from a canonical pump-probe experiment and demonstrate 130 ± 20 fs (FWHM) temporal resolution. We further analyze possible timing jitter sources and point to future improvements.
High performance magnetocaloric perovskites for magnetic refrigeration
Authors: Bahl Christian R. H. , Velázquez David , Nielsen Kaspar K. , Engelbrecht Kurt , Andersen Kjeld B. , Bulatova Regina , Pryds Nini
Published: March 2012

We have applied mixed valance manganite perovskites as magnetocaloric materials in a magnetic refrigeration device. Relying on exact control of the composition and a technique to process the materials into single adjoined pieces, we have observed temperature spans above 9 K with two materials. Reasonable correspondence is found between experiments and a 2D numerical model, using the measured magnetocaloric properties of the two materials as input.
JETTA: junction and exon toolkits for transcriptome analysis
Authors: Seok Junhee , Xu Weihong , Gao Hong , Davis Ronald W. , Xiao Wenzhong
Published: March 2012

Summary: High-throughput genome-wide studies of alternatively spliced mRNA transcripts have become increasingly important in clinical research. Consequently, easy-to-use software tools are required to process data from these studies, for example, using exon and junction arrays. Here, we introduce JETTA, an integrated software package for the calculation of gene expression indices as well as the identification and visualization of alternative splicing events. We demonstrate the software using data of human liver and muscle samples hybridized on an exon–junction array.

Availability: JETTA and its demonstrations are freely available at http://igenomed.stanford.edu/~junhee/JETTA/index.html

Contacts:  wxiao1@partners.org
Changes in Barents Sea ecosystem state, 1970–2009: climate fluctuations, human impact, and trophic interactions
Authors: Johannesen Edda , Ingvaldsen Randi B. , Bogstad Bjarte , Dalpadado Padmini , Eriksen Elena , Gjøsæter Harald , Knutsen Tor , Skern-Mauritzen Mette , Stiansen Jan Erik
Published: March 2012

Johannesen, E., Ingvaldsen, R. B., Bogstad, B., Dalpadado, P., Eriksen, E., Gjøsæter, H., Knutsen, T., Skern-Mauritzen, M., and Stiansen, J. E. 2012. Changes in Barents Sea ecosystem state, 1970–2009: climate fluctuations, human impact, and trophic interactions. – ICES Journal of Marine Science, 69: 880–889. Long time-series of data from the Barents Sea (BS) are analysed to contrast the climate, fishing pressure, plankton, pelagic fish, demersal fish, and interactions between trophic levels in a recent decade (2000–2009) with the period 1970–1999. During the past four decades, fishing pressure and climatic conditions have varied greatly in the BS, and stock levels have fluctuated substantially. Trophic control has changed from mainly bottom–up to top–down, then back to mainly bottom–up. No clear evidence for persistent ecological regimes was found. The past decade has been the warmest on record, with large stocks of demersal and pelagic fish, and increasing abundances of krill and shrimp. Except perhaps for the rather less-studied Arctic species, the short-term effect of the recent warming has been positive for BS stocks. However, as many of the long-established relationships and mechanisms in the BS seem to be changing, the long-term effects of warming are uncertain.
Early Treatment with Risperidone for Subsyndromal Delirium after On-pump Cardiac Surgery in the Elderly
Authors: Hakim Sameh M. , Othman Ahmed I. , Naoum Dina O.
Published: March 2012

Background

The aim of this randomized, parallel-arm trial was to study the effect of treating subsyndromal delirium with risperidone on the incidence of clinical delirium in elderly patients who underwent on-pump cardiac surgery.

Methods

One hundred one patients aged 65 yr or older who experienced subsyndromal delirium after on-pump cardiac surgery were randomized using a computer-generated list to receive 0.5 mg risperidone (n = 51) or placebo (n = 50) every 12 h by mouth. Patients were assessed at 8 h by a blinded observer using the Intensive Care Delirium Screening Checklist, and those scoring more than 3 were evaluated by a blinded psychiatrist to confirm delirium. Patients in either group who experienced delirium were treated according to the same algorithm. Initially, risperidone was administered and if symptoms were not controlled, haloperidol was administered. The primary outcome was the proportion of patients who experienced delirium in either group.

Results

Seven (13.7%) patients in the risperidone group experienced delirium versus 17 (34%) in the placebo group (P = 0.031) Competing-risks regression analysis showed that failure to treat subsyndromal delirium with risperidone was an independent risk factor for delirium (subhazard ratio, 3.83; 95% CI, 1.63-8.98; P = 0.002). Two (3.9%) patients in the risperidone group experienced extrapyramidal manifestations versus one (2%) in the placebo group (P = 1.0).

Conclusion

Administration of risperidone to elderly patients who experienced subsyndromal delirium after on-pump cardiac surgery was associated with significantly lower incidence of delirium. Larger studies are required to determine whether early administration of risperidone during the subsyndromal phase of delirium would influence the clinical course of such patients.
Reliability and Validity of Child/Adolescent Food Frequency Questionnaires That Assess Foods and/or Food Groups
Authors: Kolodziejczyk Julia K. , Merchant Gina , Norman Gregory J.
Published: March 2012

Objective:

Summarize the validity and reliability of child/adolescent food frequency questionnaires (FFQs) that assess food and/or food groups.

Methods:

We performed a systematic review of child/adolescent (6–18 years) FFQ studies published between January 2001 and December 2010 using MEDLINE, Cochrane Library, PsycINFO, and Google Scholar. Main inclusion criteria were peer reviewed, written in English, and reported reliability or validity of questionnaires that assessed intake of food/food groups. Studies were excluded that focused on diseased people or used a combined dietary assessment method. Two authors independently selected the articles and extracted questionnaire characteristics such as number of items, portion size information, time span, category intake frequencies, and method of administration. Validity and reliability coefficients were extracted and reported for food categories and averaged across food categories for each study.

Results:

Twenty‐one studies were selected from 873, 18 included validity data, and 14 included test‐retest reliability data. Publications were from the United States, Europe, Africa, Brazil, and the south Pacific. Validity correlations ranged from 0.01 to 0.80, and reliability correlations ranged from 0.05 to 0.88. The highest average validity correlations were obtained when the questionnaire did not assess portion size, measured a shorter time span (ie, previous day/week), was of medium length (ie, ∼20–60 items), and was not administered to the child's parents.

Conclusions:

There are design and administration features of child/adolescent FFQs that should be considered to obtain reliable and valid estimates of dietary intake in this population.
Acute Febrile Cholestatic Jaundice in Children
Authors: Taddio Andrea , Pellegrin Maria Chiara , Centenari Chiara , Filippeschi Irene Pellegrini , Ventura Alessandro , Maggiore Giuseppe
Published: March 2012

Kawasaki disease (KD) is characterized by persistent fever in addition to 4 of 5 signs of mucocutaneous inflammation. Although gastrointestinal involvement does not belong to the classic diagnostic criteria, it has been often associated with KD onset. We reviewed patients who were admitted for febrile cholestatic jaundice between 2003 and 2010 in 2 tertiary pediatric care centers. KD was the second most frequent cause (21%) after viral infections. Considering the relative high frequency of this condition, a high index of suspicion of KD should be maintained in patients presenting with febrile cholestatic jaundice.
A mechanical Turing machine: blueprint for a biomolecular computer
Authors: Shapiro Ehud
Published: March 2012

We describe a working mechanical device that embodies the theoretical computing machine of Alan Turing, and as such is a universal programmable computer. The device operates on three-dimensional building blocks by applying mechanical analogues of polymer elongation, cleavage and ligation, movement along a polymer, and control by molecular recognition unleashing allosteric conformational changes. Logically, the device is not more complicated than biomolecular machines of the living cell, and all its operations are part of the standard repertoire of these machines; hence, a biomolecular embodiment of the device is not infeasible. If implemented, such a biomolecular device may operate
in vivo
, interacting with its biochemical environment in a program-controlled manner. In particular, it may ‘compute’ synthetic biopolymers and release them into its environment in response to input from the environment, a capability that may have broad pharmaceutical and biological applications.
Trends, noise and re-entrant long-term persistence in Arctic sea ice
Authors: Agarwal S. , Moon W. , Wettlaufer J. S.
Published: March 2012

We examine the long-term correlations and multi-fractal properties of daily satellite retrievals of Arctic sea ice albedo and extent, for periods of approximately 23 years and 32 years, respectively. The approach harnesses a recent development called multi-fractal temporally weighted detrended fluctuation analysis, which exploits the intuition that points closer in time are more likely to be related than distant points. In both datasets, we extract multiple crossover times, as characterized by generalized Hurst exponents, ranging from synoptic to decadal. The method goes beyond treatments that assume a single decay scale process, such as a first-order autoregression, which cannot be justifiably fitted to these observations. Importantly, the strength of the seasonal cycle ‘masks’ long-term correlations on time scales beyond seasonal. When removing the seasonal cycle from the original record, the ice extent data exhibit white noise behaviour from seasonal to bi-seasonal time scales, whereas the clear fingerprints of the short (weather) and long (approx. 7 and 9 year) time scales remain, the latter associated with the recent decay in the ice cover. Therefore, long-term persistence is re-entrant beyond the seasonal scale and it is not possible to distinguish whether a given ice extent minimum/maximum will be followed by a minimum/maximum that is larger or smaller in magnitude.
Surface chromium single sites: open problems and recent advances
Authors: Zecchina Adriano , Groppo Elena
Published: March 2012

The results of decades of studies on the Phillips chromium (Cr)/silica polymerization catalyst are briefly summarized. The application of several characterization methods has allowed a detailed knowledge of the structure and reactivity of Cr centres to be obtained. In particular, many aspects of this apparently simple single-site catalyst, including the heterogeneity, the modification of the ligand sphere upon interaction with many molecules and the initiation mechanism of the ethylene polymerization reaction, have been clarified. It is shown that based on the acquired knowledge, it is now possible to proceed further towards the intelligent modification of the ligand sphere with the scope to increase the reaction rate and selectivity. It is also illustrated that, besides polymerization/oligomerization reactions, it is possible to extend the study of Cr
II
reactivity towards new reactions.
Arrested embryonic development: a review of strategies to delay hatching in egg-laying reptiles
Authors: Rafferty Anthony R. , Reina Richard D.
Published: March 2012

Arrested embryonic development involves the downregulation or cessation of active cell division and metabolic activity, and the capability of an animal to arrest embryonic development results in temporal plasticity of the duration of embryonic period. Arrested embryonic development is an important reproductive strategy for egg-laying animals that provide no parental care after oviposition. In this review, we discuss each type of embryonic developmental arrest used by oviparous reptiles. Environmental pressures that might have directed the evolution of arrest are addressed and we present previously undiscussed environmentally dependent physiological processes that may occur in the egg to bring about arrest. Areas for future research are proposed to clarify how ecology affects the phenotype of developing embryos. We hypothesize that oviparous reptilian mothers are capable of providing their embryos with a level of phenotypic adaptation to local environmental conditions by incorporating maternal factors into the internal environment of the egg that result in different levels of developmental sensitivity to environmental conditions after they are laid.
Plankton reach new heights in effort to avoid predators
Authors: Gemmell Brad J. , Jiang Houshuo , Strickler J. Rudi , Buskey Edward J.
Published: March 2012

The marine environment associated with the air–water interface (neuston) provides an important food source to pelagic organisms where subsurface prey is limited. However, studies on predator–prey interactions within this environment are lacking. Copepods are known to produce strong escape jumps in response to predators, but must contend with a low-Reynolds-number environment where viscous forces limit escape distance. All previous work on copepod interaction with predators has focused on a liquid environment. Here, we describe a novel anti-predator behaviour in two neustonic copepod species, where individuals frequently exit the water surface and travel many times their own body length through air to avoid predators. Using both field recordings with natural predators and high-speed laboratory recordings, we obtain detailed kinematics of this behaviour, and estimate energetic cost associated with this behaviour. We demonstrate that despite losing up to 88 per cent of their initial kinetic energy, copepods that break the water surface travel significantly further than those escaping underwater and successfully exit the perceptive field of the predator. This behaviour provides an effective defence mechanism against subsurface-feeding visual predators and the results provide insight into trophic interactions within the neustonic environment.
The benefit of being a social butterfly: communal roosting deters predation
Authors: Finkbeiner Susan D. , Briscoe Adriana D. , Reed Robert D.
Published: March 2012

Aposematic passion-vine butterflies from the genusHeliconiusform communal roosts on a nightly basis. This behaviour has been hypothesized to be beneficial in terms of information sharing and/or anti-predator defence. To better understand the adaptive value of communal roosting, we tested these two hypotheses in field studies. The information-sharing hypothesis was addressed by examining following behaviour of butterflies departing from natural roosts. We found no evidence of roost mates following one another to resources, thus providing no support for this hypothesis. The anti-predator defence hypothesis was tested using avian-indiscriminableHeliconius eratomodels placed singly and in aggregations at field sites. A significantly higher number of predation attempts were observed on solitary models versus aggregations of models. This relationship between aggregation size and attack rate suggests that communally roosting butterflies enjoy the benefits of both overall decreased attack frequency as well as a prey dilution effect. Communal roosts probably deter predators through collective aposematism in which aggregations of conspicuous, unpalatable prey communicate a more effective repel signal to predators. On the basis of our results, we propose that predation by birds is a key selective pressure maintainingHeliconiuscommunal roosting behaviour.
Targeted gene addition to a predetermined site in the human genome using a ZFN-based nicking enzyme
Authors: Wang Jianbin , Friedman Geoffrey , Doyon Yannick , Wang Nathaniel S. , Li Carrie Jiaxin , Miller Jeffrey C. , Hua Kevin L. , Yan Jenny Jiacheng , Babiarz Joshua E. , Gregory Philip D. , Holmes Michael C.
Published: March 2012

Zinc-finger nucleases (ZFNs) drive highly efficient genome editing by generating a site-specific DNA double-strand break (DSB) at a predetermined site in the genome. Subsequent repair of this break via the nonhomologous end-joining (NHEJ) or homology-directed repair (HDR) pathways results in targeted gene disruption or gene addition, respectively. Here, we report that ZFNs can be engineered to induce a site-specific DNA single-strand break (SSB) or nick. Using the CCR5-specific ZFNs as a model system, we show that introduction of a nick at this target site stimulates gene addition using a homologous donor template but fails to induce significant levels of the small insertions and deletions (indels) characteristic of repair via NHEJ. Gene addition by these CCR5-targeted zinc finger nickases (ZFNickases) occurs in both transformed and primary human cells at efficiencies of up to ∼1%–8%. Interestingly, ZFNickases targeting the AAVS1 “safe harbor” locus revealed similar in vitro nicking activity, a marked reduction of indels characteristic of NHEJ, but stimulated far lower levels of gene addition—suggesting that other, yet to be identified mediators of nick-induced gene targeting exist. Introduction of site-specific nicks at distinct endogenous loci provide an important tool for the study of DNA repair. Moreover, the potential for a SSB to direct repair pathway choice (i.e., HDR but not NHEJ) may prove advantageous for certain therapeutic applications such as the targeted correction of human disease-causing mutations.
Overexpression of PIP2;5 Aquaporin Alleviates Effects of Low Root Temperature on Cell Hydraulic Conductivity and Growth in Arabidopsis
Authors: Lee Seong Hee , Chung Gap Chae , Jang Ji Young , Ahn Sung Ju , Zwiazek Janusz J.
Published: March 2012

The effects of low root temperature on growth and root cell water transport were compared between wild-type Arabidopsis (Arabidopsis thaliana) and plants overexpressing plasma membrane intrinsic protein 1;4 (PIP1;4) and PIP2;5. Descending root temperature from 25°C to 10°C quickly reduced cell hydraulic conductivity (Lp) in wild-type plants but did not affect Lp in plants overexpressing PIP1;4 and PIP2;5. Similarly, when the roots of wild-type plants were exposed to 10°C for 1 d, Lp was lower compared with 25°C. However, there was no effect of low root temperature on Lp in PIP1;4- and PIP2;5-overexpressing plants after 1 d of treatment. When the roots were exposed to 10°C for 5 d, Lp was reduced in wild-type plants and in plants overexpressing PIP1;4, whereas there was still no effect in PIP2;5-overexpressing plants. These results suggest that the gating mechanism in PIP1;4 may be more sensitive to prolonged low temperature compared with PIP2;5. The reduction of Lp at 10°C in roots of wild-type plants was partly restored to the preexposure level by 5 mm Ca(NO3)2 and protein phosphatase inhibitors (75 nm okadaic acid or 1 μm Na3VO4), suggesting that aquaporin phosphorylation/dephosphorylation processes were involved in this response. The temperature sensitivity of cell water transport in roots was reflected by a reduction in shoot and root growth rates in the wild-type and PIP1;4-overexpressing plants exposed to 10°C root temperature for 5 d. However, low root temperature had no effect on growth in plants overexpressing PIP2;5. These results provide strong evidence for a link between growth at low root temperature and aquaporin-mediated root water transport in Arabidopsis.
Ligand‐triggered resistance to molecular targeted drugs in lung cancer: Roles of hepatocyte growth factor and epidermal growth factor receptor ligands
Authors: Yano Seiji , Takeuchi Shinji , Nakagawa Takayuki , Yamada Tadaaki
Published: March 2012

Recent advances in molecular biology have led to the identification of new molecular targets, such as epidermal growth factor receptor (
EGFR
) mutations and echinoderm microtubule‐associated protein‐like 4 (EML4) – anaplastic lymphoma kinase (ALK) fusion gene, in lung cancer. Dramatic response has been achieved with EGFR inhibitors (gefitinib and erlotinib) and an ALK inhibitor (crizotinib) in lung cancer expressing corresponding targets. However, cancer cells acquire resistance to these drugs and cause recurrence. Known major mechanisms for resistance to molecular targeted drugs include gatekeeper mutations in the target gene and activation of bypass survival signal via receptors other than the target receptors. The latter mechanism can involve receptor gene amplification and ligand‐triggered receptor activation as well. For example, hepatocyte growth factor (HGF), the ligand of a tyrosine kinase receptor Met, activates Met and the downstream PI3K/Akt pathway and triggers resistance to EGFR inhibitors in
EGFR
mutant lung cancer cells. Moreover, EGFR ligands activate EGFR and downstream pathways and trigger resistance to crizotinib in
EML4‐ALK
lung cancer cells. These observations indicate that signals from oncogenic drivers (EGFR signaling in
EGFR
‐mutant lung cancer and ALK signaling in
EML4‐ALK
lung cancer) and ligand‐triggered bypass signals (HGF‐Met and EGFR ligands‐EGFR, respectively) must be simultaneously blocked to avoid the resistance. This review focuses specifically on receptor activation by ligand stimulation and discusses novel therapeutic strategies that are under development for overcoming resistance to molecular targeted drugs in lung cancer. (Cancer Sci 2012; 103: 1189–1194)
Cytomegalovirus‐induced T‐cell proliferation and the development of progressive multifocal leucoencephalopathy following bone marrow transplantation
Authors: Owen R. G. , Patmore R. D. , Smith G. M. , Barnard D. L.
Published: March 2012

Summary. Progressive multifocal leucoencephalopathy (PML) is a rare disorder characterized by progressive demyelination within the brain. It is usually fatal and occurs when there are defects in cell‐mediated immunity. We report a case of PML which developed following allogeneic bone marrow transplantation. It was preceded by the development of a persistent polyclonal expansion of large granular lymphocytes (LGLs) which appeared to rise as a consequence of cytomegalovirus infection.
Back‐scattered electron imaging combined with EBSD technique for characterization of pearlitic steels
Authors: GUO N. , LIU Q.
Published: March 2012

Microstructure of pearlitic steels subjected different heat treatments were characterized combining the usage of back‐scattered electron imaging and electron backscatter diffraction in a scanning electron microscope. The results indicated that the method used in current study enabled the acquisition of pearlite nodule, colony and interlamellar spacing of pearlite structure only through sample preparation of one time. Both the morphology of pearlite lamellae and the crystallographic orientation of ferrite matrix can be released in back‐scattered electron imaging image and electron backscatter diffraction micrograph acquired at the same region. The definitions of pearlite colony and the low‐angle boundaries existed in ferrite matrix were also discussed based on this method.
Dental occlusion, body posture and temporomandibular disorders: where we are now and where we are heading for
Authors: MANFREDINI D. , CASTROFLORIO T. , PERINETTI G. , GUARDA‐NARDINI L.
Published: March 2012

Summary  The aim of this investigation was to perform a review of the literature dealing with the issue of relationships between dental occlusion, body posture and temporomandibular disorders (TMD). A search of the available literature was performed to determine what the current evidence is regarding: (i) The physiology of the dental occlusion–body posture relationship, (ii) The relationship of these two topics with TMD and (iii) The validity of the available clinical and instrumental devices (surface electromyography, kinesiography and postural platforms) to measure the dental occlusion–body posture–TMD relationship. The available posturographic techniques and devices have not consistently found any association between body posture and dental occlusion. This outcome is most likely due to the many compensation mechanisms occurring within the neuromuscular system regulating body balance. Furthermore, the literature shows that TMD are not often related to specific occlusal conditions, and they also do not have any detectable relationships with head and body posture. The use of clinical and instrumental approaches for assessing body posture is not supported by the wide majority of the literature, mainly because of wide variations in the measurable variables of posture. In conclusion, there is no evidence for the existence of a predictable relationship between occlusal and postural features, and it is clear that the presence of TMD pain is not related with the existence of measurable occluso‐postural abnormalities. Therefore, the use instruments and techniques aiming to measure purported occlusal, electromyographic, kinesiographic or posturographic abnormalities cannot be justified in the evidence‐based TMD practice.
Impact of neoadjuvant transarterial chemoembolization on tumor recurrence and patient survival after liver transplantation for hepatocellular carcinoma: a retrospective analysis
Authors: Seehofer Daniel , Nebrig Maxim , Denecke Timm , Kroencke Thomas , Weichert Wilko , Stockmann Martin , Somasundaram Rajan , Schott Eckart , Puhl Gero , Neuhaus Peter
Published: March 2012

Transarterial chemoembolization (TACE) has gained wide acceptance as a bridge to liver transplantation (LT) in patients with hepatocellular carcinoma (HCC). Aim of this analysis was to compare long‐term results with and without neoadjuvant TACE and to identify subgroups, which particularly benefit from TACE.

Patients with HCC transplanted at our center were retrospectively analyzed. The following were excluded to increase consistency: incidental‐HCC, Child‐C, living‐related‐LT, other HCC‐specific‐treatment. Of 336 patients, 177 were subject of this analysis, 71 received TACE and 106 no HCC therapy.

Patients with and without TACE showed similar five‐yr survival (73/67%) and recurrence rates (23/29%). Progression on the waiting list was associated with a higher recurrence rate in the TACE (50 vs.12%) and the non‐TACE group (40 vs. 22%). HCC recurrence was reduced in patients inside Milan (0.053) and UCSF (0.037) criteria by neoadjuvant TACE but not outside UCSF (0.99). Also a trend towards an improved survival was seen within these criteria.

Our large single center experience suggests that TACE lowers the HCC recurrence rate in patients inside the Milan and UCSF criteria. Moreover, the response to TACE is a good indicator of low recurrence rates. The effect of TACE might be more pronounced in patients with longer waiting time than in this cohort (mean, 4.6 months).
Impact of rifaximin use for hepatic encephalopathy on the risk of early post‐transplant infections in liver transplant recipients
Authors: Sun Hsin‐Yun , Wagener Marilyn , Cacciarelli Thomas V. , Singh Nina
Published: March 2012

Background

Whether the use of rifaximin for hepatic encephalopathy during liver transplant candidacy has an impact on post‐transplant infections is not known.

Methods

We compared the frequency and spectrum of infections within 90 d post‐transplant in liver transplant recipients who did and did not receive rifaximin for hepatic encephalopathy during transplant candidacy.

Results

Of 110 consecutive liver transplant recipients, 30 (27%) received rifaximin. Rifaximin users were more severely ill based on higher Model for End‐Stage Liver Disease (MELD) score (p = 0.005). When controlled for MELD (stratified by MELD < 30, MELD ≥ 30), the risk of infections was significantly lower in rifaximin vs. no rifaximin recipients (OR = 0.269, 95% CI 0.078–0.0.934, p = 0.026). Rifaximin use was not associated with a higher risk of multidrug resistant bacterial infections (OR = 1.8, 95% CI 0.42–8.35, p = 0.40). The probability of post‐transplant survival at 90 d did not differ for patients with or without rifaximin use (0.90 for both groups, p = 0.56).

Conclusions

Rifaximin appeared to have a protective effect against early post‐transplant infections in more severely ill liver transplant recipients. Rifaximin use did not select for multidrug resistant bacteria in these patients.