bluuebunny/crossref_metadata_2025 huggingface dataset:
Sample conditions to avoid pH distortion in RP‐LC
Authors: Samuelsson Jörgen , Forssén Patrik , Fornstedt Torgny
Published: October 2013

Band deformations might take place for acids and bases in preparative applications and adsorption studies where it is necessary to use overloaded injections. In this study, we focus on how deformations can be prevented without using highly concentrated buffers that may precipitate in the eluent. We have systematically investigated how the elution zones depend on which protolytic form the analyte has when it is dissolved. Basic and acidic model compounds are investigated using eluents with different pH values and the resulting elution profiles are compared when the analytes are dissolved in their protonated and deprotonated form, i.e., in uncharged form or as different kinds of salts. Depending on the analyte's protolytic form, a sample zone is created at the column inlet whose pH deviates, more or less, from the bulk eluent's. If the local adsorption strength in this sample zone is greater than the bulk eluent's, the elution profiles are compressed. Under opposite conditions, the eluted bands are more or less deformed and may even be split; completely different deformations can even take place for different kinds of salt combinations. Explanations of these, and other, effects, together with detailed guidelines for proper sample preparation to avoid peak deformations, are given.
Polyhedral Oligosilsesquioxane (POSS) Nanoparticle Localization in Ordered Structures Formed by Solvated Block Copolymers
Authors: Sarkar Biswajit , Ayandele Ebunoluwa , Venugopal Vinithra , Alexandridis Paschalis
Published: October 2013

The coassembly of polyhedral oligosilsesquioxanes (POSS) of two different surface chemistries is considered, one hydrophilic, poly(ethylene oxide) (PEO), and the other hydrophobic, isobutyl (iB), in cylindrical structures formed by hydrated poly(ethylene oxide)‐poly(propylene oxide)‐poly(ethylene oxide) block copolymer, Pluronic P105 (EO37PO56EO37). Incorporation of PEO‐POSS by replacing an equal mass of water results in an increase in the lattice parameter (d), which is attributed to an increase in the degree of block segregation. In the case of adding PEO‐POSS at a fixed Pluronic P105/water ratio, d ~ φpolymer‐0.7, which suggests that PEO‐POSS particles are located inside the hydrated PEO domains. Incorporation of iB‐POSS in the water‐in‐xylene cylindrical structure causes an order‐to‐order phase transition to a bicontinuous cubic structure, which suggests that iB‐POSS decreases the degree of block segregation by locating at the PEO‐PPO interfacial regions. The nanoparticle versus molecule nature of POSS is discussed by comparing POSS effects to those of 10.6 nm diameter deprotonated silica nanoparticles and of glycerol or glucose.

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Concentration Fluctuations and Segmental Dynamics in Weakly Dynamic Asymmetric Blends in the Presence of Surface‐Functionalized Multiwall Carbon Nanotubes
Authors: Sharma Keshav , Sharma Maya , Chandra Aman , Bose Suryasarathi
Published: October 2013

Surface‐functionalized multiwall carbon nanotubes (MWCNTs) are incorporated in poly(methyl methacrylate)/styrene acrylonitrile (PMMA/SAN) blends and the pretransitional regime is monitored in situ by melt rheology and dielectric spectroscopy. As the blends exhibit weak dynamic asymmetry, the obvious transitions in the melt rheology due to thermal concentration fluctuations are weak. This is further supported by the weak temperature dependence of the correlation length (ξ ≈ 10–12 Å) in the vicinity of demixing. Hence, various rheological techniques in both the temperature and frequency domains are adopted to evaluate the demixing temperature. The spinodal decomposition temperature is manifested in an increase in the miscibility gap in the presence of MWCNTs. Furthermore, MWCNTs lead to a significant slowdown of the segmental dynamics in the blends. Thermally induced phase separation in the PMMA/SAN blends lead to selective localization of MWCNTs in the PMMA phase. This further manifests itself in a significant increase in the melt conductivity.

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Controlled Thiol‐Ene Functionalization of Polyferrocenylsilane‐block‐Polyvinylsiloxane Copolymers
Authors: Lunn David J. , Boott Charlotte E. , Bass Kelly E. , Shuttleworth Timothy A. , McCreanor Niall G. , Papadouli Sofia , Manners Ian
Published: October 2013

A general route for the controlled functionalization of polyferrocenylsilane‐block‐polyvinylsiloxane copolymers, which should be transferable to other silicone‐based materials, is developed utilizing the photoinitiated thiol‐ene reaction. Poly(ferrocenyldimethylsilane)54‐block‐poly(methylvinylsiloxane)510 (PFDMS54‐b‐PMVS510) is synthesized via sequential living anionic polymerization and quantitatively functionalized with a range of thiols, with the aim of tuning the solubility of the resulting materials for self‐assembly studies or incorporating more complex functionality for subsequent applications. When functionalization is attempted using a deficit of thiol, the photoinitiator 2,2‐dimethoxy‐2‐phenylacetophenone, used to accelerate the radical reaction, is found to cause significant cross‐linking of the polysiloxane chain. Reproducible percentage thiol‐ene functionalization of the polysiloxane block can be achieved by the use of PFDMS53‐b‐PMVS58/PDMS444 (PDMS = polydimethylsiloxane), prepared by the copolymerization of cyclic siloxane monomers, [Me(CHCH2)SiO]3 and [Me2SiO]3, to tune the vinyl group incorporation pre‐functionalization.

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Three‐dimensional whole‐brain perfusion quantification using pseudo‐continuous arterial spin labeling MRI at multiple post‐labeling delays: accounting for both arterial transit time and impulse response function
Authors: Qin Qin , Huang Alan J. , Hua Jun , Desmond John E. , Stevens Robert D. , van Zijl Peter C. M.
Published: October 2013

Measurement of the cerebral blood flow (CBF) with whole‐brain coverage is challenging in terms of both acquisition and quantitative analysis. In order to fit arterial spin labeling‐based perfusion kinetic curves, an empirical three‐parameter model which characterizes the effective impulse response function (IRF) is introduced, which allows the determination of CBF, the arterial transit time (ATT) and T1,eff. The accuracy and precision of the proposed model were compared with those of more complicated models with four or five parameters through Monte Carlo simulations. Pseudo‐continuous arterial spin labeling images were acquired on a clinical 3‐T scanner in 10 normal volunteers using a three‐dimensional multi‐shot gradient and spin echo scheme at multiple post‐labeling delays to sample the kinetic curves. Voxel‐wise fitting was performed using the three‐parameter model and other models that contain two, four or five unknown parameters. For the two‐parameter model, T1,eff values close to tissue and blood were assumed separately. Standard statistical analysis was conducted to compare these fitting models in various brain regions. The fitted results indicated that: (i) the estimated CBF values using the two‐parameter model show appreciable dependence on the assumed T1,eff values; (ii) the proposed three‐parameter model achieves the optimal balance between the goodness of fit and model complexity when compared among the models with explicit IRF fitting; (iii) both the two‐parameter model using fixed blood T1 values for T1,eff and the three‐parameter model provide reasonable fitting results. Using the proposed three‐parameter model, the estimated CBF (46 ± 14 mL/100 g/min) and ATT (1.4 ± 0.3 s) values averaged from different brain regions are close to the literature reports; the estimated T1,eff values (1.9 ± 0.4 s) are higher than the tissue T1 values, possibly reflecting a contribution from the microvascular arterial blood compartment.
Zooarchaeological and Stable Isotopic Assessments on Pinniped–Human Relations in the Beagle Channel (Tierra del Fuego, Southern South America)
Authors: Zangrando A . F. , Panarello H. , Piana E.  L.
Published: October 2013

Recent zooarchaeological investigations in the Beagle Channel region have shown long‐term variations characterised by a high inter‐taxonomic dominance of pinnipeds during the first moments of the archaeological sequence (ca 6400bp) at the Túnel Locality and a decrease in the relative importance of this resource and a diversification of subsistence in that place since 5500bp. Two possible explanations for these variations are evaluated: (i) variations in foraging habits of pinnipeds that would lead to changes in the degree of predictability or access to the resource and (ii) a reduction in resource availability because of increased human predation pressure. To analyse these arguments, this paper presents and discusses the results of an analysis of stable isotopes (δ13C and δ15N) from collagen samples of South American fur seals (Arctocephalus australis) and representations of age and size of pinnipeds in the archaeological record of Túnel. Stable isotope analyses suggest that there were variations in the foraging behaviour of southern fur seals at the same time that zooarchaeological analyses record decreases of the ages and sizes of the hunted prey. On the basis of these results, an increase of hunter–gatherer predation pressure on pinnipeds to the Middle–Late Holocene in southern South America is suggested. Copyright © 2013 John Wiley & Sons, Ltd.
Estimating twin concordance for bivariate competing risks twin data
Authors: Scheike Thomas H. , Holst Klaus K. , Hjelmborg Jacob B.
Published: October 2013

For twin time‐to‐event data, we consider different concordance probabilities, such as the casewise concordance that are routinely computed as a measure of the lifetime dependence/correlation for specific diseases. The concordance probability here is the probability that both twins have experienced the event of interest. Under the assumption that both twins are censored at the same time, we show how to estimate this probability in the presence of right censoring, and as a consequence, we can then estimate the casewise twin concordance. In addition, we can model the magnitude of within pair dependence over time, and covariates may be further influential on the marginal risk and dependence structure. We establish the estimators large sample properties and suggest various tests, for example, for inferring familial influence. The method is demonstrated and motivated by specific twin data on cancer events with the competing risk death. We thus aim to quantify the degree of dependence through the casewise concordance function and show a significant genetic component. Copyright © 2013 John Wiley & Sons, Ltd.
From youth worker professional development to organizational change
Authors: Rana Sheetal , Baumgardner Briana , Germanic Ofir , Graff Randy , Korum Kathy , Mueller Megan , Randall Steve , Simmons Tim , Stokes Gina , Xiong Will , Peterson Karen Kolb
Published: October 2013

An ongoing, innovative youth worker professional development is described in this article. This initiative began as youth worker professional development and then transcended to personal and organizational development. It grew from a moral response of Saint Paul Parks and Recreation staff and two faculty members of Youth Studies, University of Minnesota to offer higher‐quality services to youth for their healthy development. Its underlying philosophies and ethos included building and sustaining meaningful relationships, cocreating a space for learning and change, becoming a reflecting practitioner, and community organizing. This professional development responded to the participants' interests and needs or to local situations in that moment, that space, and the discussions, and took on different shapes at different times. There were many accomplishments of, challenges and barriers to, and lessons learned from this professional development.
From lessons learned to emerging practices
Authors: Baizerman Michael , Roholt Ross VeLure , Korum Kathy , Rana Sheetal
Published: October 2013

Organizational development is based in part on knowledge development, both formal, scientifically proven and also nonscientific practice wisdom. This article brings together all of the lessons learned over our six years of work with Saint Paul Parks and Recreation, and suggests the practice utility of these.
Two Synthetic Approaches to Ag3.4In3.7Sb76.4Te16.5 Bulk ­Samples and their Transport Properties
Authors: Schröder Thorsten , Rosenthal Tobias , Gold Christian , Scheidt Ernst‐Wilhelm , Schnick Wolfgang , Oeckler Oliver
Published: October 2013

Bulk samples with the chemical composition of the AIST phase‐change material Ag3.4In3.7Sb76.4Te16.5 were synthesized by melt spinning as well as under high‐pressure conditions (12 GPa), respectively. Rietveld refinements as well as selected‐area electron diffraction patterns and high‐resolution transmission electron images show that both types of samples crystallize in the gray As structure type. All atoms are disordered on one Wyckoff position. The metrics of the high‐pressure sample appear compressed along [001] compared to the ones of the melt‐spun sample. This may be attributed to strain, probably caused by twinning, which relaxes at higher temperatures (starting at ca. 130 °C). The compounds decompose at 250 °C and a structural change of the Sb‐rich Sb/Te phase was observed at 440 °C. The thermoelectric properties of an annealed sample with AgInTe2 impurities were measured and result in a ZT value of 0.003 at room temperature, which strongly increases with temperature.
Quantum black hole entropy and the holomorphic prepotential of $ \mathcal{N}=2 $ supergravity
Authors: Murthy Sameer , Reys Valentin
Published: October 2013

Abstract

Supersymmetric terms in the effective action of
$ \mathcal{N}=2 $
supergravity in four dimensions are generically classified into chiral-superspace integrals and full-superspace integrals. For a theory of
$ \mathcal{N}=2 $
vector multiplets coupled to supergravity, a special class of couplings is given by chiral-superspace integrals that are governed by a holomorphic prepotential function. The quantum entropy of BPS black holes in such theories depends on the prepotential according to a known integral formula. We show, using techniques of localization, that a large class of full-superspace integrals in the effective action of
$ \mathcal{N}=2 $
supergravity do not contribute to the quantum entropy of BPS black holes at any level in the derivative expansion. Our work extends similar results for semi-classical supersymmetric black hole entropy, and goes towards providing an explanation of why the prepotential terms capture the exact microscopic quantum black hole entropy.
Plating of Metacarpal Fractures with Locked or Nonlocked Screws, a Biomechanical Study: How Many Cortices are Really Necessary?
Authors: Barr Cameron , Behn Anthony W , Yao Jeffrey
Published: October 2013

Background

Dorsal plate and screw fixation is a popular choice for metacarpal stabilization. The balance between construct stability and soft tissue dissection remains a surgical dilemma. Historically, six cortices of bone fixation on either side of a fracture were deemed necessary. This study aims to elucidate whether four cortices of locked fixation on either side of the fracture is equivalent to the current gold standard of six cortices of nonlocked fixation on either side of the fracture. If so, less dissection to insert shorter plates with fewer screws could be used to stably fix these fractures.

Methods

With biomechanical testing-grade composite Sawbones, a comminuted metacarpal fracture model was used to test two fixation constructs consisting of a standard dorsal plate and either six bicortical nonlocking screws (three screws per segment) or four bicortical locking screws (two screws per segment). Thirty specimens were tested to failure in cantilever bending and torsion.

Results

There was statistical equivalence between the locking and nonlocking constructs in cantilever bending stiffness, torsional stiffness, maximum bending load, and maximum torque.

Conclusion

The tested metacarpal fracture model had equivalent biomechanical properties when fixed with a standard dorsal plate and either six bicortical nonlocking screws or four bicortical locking screws. By utilizing fewer cortices of fixation, there will be less dissection and less soft tissue stripping during fixation of metacarpal fractures. This will also be of benefit in very proximal or distal fractures as multiple cortices of fixation are often difficult to obtain during stabilization of these challenging fractures.
Consumer Power: Evolution in the Digital Age
Authors: Labrecque Lauren I. , vor dem Esche Jonas , Mathwick Charla , Novak Thomas P. , Hofacker Charles F.
Published: October 2013

The predictions of growing consumer power in the digital age that predated the turn of the century were fueled by the rise of the Internet, then reignited by social media. This article explores the intersection of consumer behavior and digital media by clearly defining consumer power and empowerment in Internet and social media contexts and by presenting a theoretical framework of four distinct consumer power sources: demand-, information-, network-, and crowd-based power. Furthermore, we highlight technology's evolutionary role in the development of these power sources and discuss the nature of shifts in power from marketers to consumers in terms of each source. The framework organizes prior marketing literature on Internet-enabled consumer empowerment and highlights gaps in current research. Specific research questions are elaborated for each source of power outlining the agenda for future research areas.
Instrumental Activities of Daily Living Staging as a Possible Clinical Tool for Falls Risk Assessment in Physical Medicine and Rehabilitation
Authors: Brown Janice , Kurichi Jibby E. , Xie Dawei , Pan Qiang , Stineman Margaret G.
Published: October 2013

Objective

To determine whether instrumental activity of daily living (IADL) limitation stages can distinguish among elderly, community‐dwelling persons with high likelihoods to have fallen once and more than once.

Design

A cross‐sectional survey.

Setting

A nationally representative sample from the Second Longitudinal Study of Aging (LSOA II).

Participants

Included were 7401 community‐dwelling persons 70 years of age and older.

Methods

The association of falling once and more than once within the past 12 months and 5 stages of increasing IADL limitation were explored by using a multinomial logistic regression model that controlled for demographics, education, perceived lack of home accessibility features, and health conditions. Sample proportions were weighted to reflect the prevalence in the U.S. population of 1994.

Main Outcome Measurements

Subject recall of fall history. There were 3 categories for this variable: no fall, falling once, and falling more than once in the past 12 months.

Results

Compared with IADL stage 0, the adjusted relative risk ratio of falling once peaked in individuals at IADL stage II at 2.0 (95% confidence interval [CI], 1.5‐2.6), and those at IADL stage III had a relative risk ratio of 1.8 (95% CI, 1.3‐2.6). The relative risk ratio of falling more than once was 2.1 (95% CI, 1.7‐2.6), 4.0 (95% CI, 3.0‐5.3), 3.7 (95% CI, 2.8‐5.0), and 2.7 (95% CI, 1.5‐4.9) for IADL stages I, II, III, and IV, respectively, when treating IADL stage 0 as reference.

Conclusions

IADL limitation stages could represent a powerful and practical tool for screening patients in the U.S. elderly population according to fall risk. Clinical implementation and prospective testing for validation as a screening tool would be necessary.
Co-Production, Polycentricity, and Value Heterogeneity: The Ostroms’ Public Choice Institutionalism Revisited
Authors: ALIGICA PAUL DRAGOS , TARKO VLAD
Published: October 2013

Revisiting the theory of institutional hybridity and diversity developed by Vincent and Elinor Ostrom to cope with the challenge of the “neither states nor markets” institutional domain, this article reconstructs the Ostromian system along the “value heterogeneity–co-production–polycentricity” axis. It articulates the elements of a theory of value heterogeneity and of the fuzzy boundaries between private and public. It rebuilds the model of co-production, clarifying the ambiguity surrounding a key technical public choice theoretical assumption, and it demonstrates (a) why it should not be confused with the Alchian-Demsetz team production model and (b) how co-production engenders a type of market failure that has been neglected so far. In light of this analysis, the article reconsiders polycentricity, the capstone of the Ostromian system, explaining why polycentricity may be seen as a solution both to this co-production market failure problem and to the problems of social choice in conditions of deep heterogeneity. It also discusses further normative corollaries.
Perturbed threat monitoring following a traumatic event predicts risk for post-traumatic stress disorder
Authors: Naim R. , Wald I. , Lior A. , Pine D. S. , Fox N. A. , Sheppes G. , Halpern P. , Bar-Haim Y.
Published: October 2013

Background

Post-traumatic stress disorder (PTSD) is a chronic and difficult to treat psychiatric disorder. Objective, performance-based diagnostic markers that uniquely index risk for PTSD above and beyond subjective self-report markers could inform attempts to improve prevention and early intervention. We evaluated the predictive value of threat-related attention bias measured immediately after a potentially traumatic event, as a risk marker for PTSD at a 3-month follow-up. We measured the predictive contribution of attentional threat bias above and beyond that of the more established marker of risk for PTSD, self-reported psychological dissociation.

Method

Dissociation symptoms and threat-related attention bias were measured in 577 motor vehicle accident (MVA) survivors (mean age = 35.02 years, 356 males) within 24 h of admission to an emergency department (ED) of a large urban hospital. PTSD symptoms were assessed at a 3-month follow-up using the Clinician-Administered PTSD Scale (CAPS).

Results

Self-reported dissociation symptoms significantly accounted for 16% of the variance in PTSD at follow-up, and attention bias toward threat significantly accounted for an additional 4% of the variance in PTSD.

Conclusions

Threat-related attention bias can be reliably measured in the context of a hospital ED and significantly predicts risk for later PTSD. Possible mechanisms underlying the association between threat bias following a potentially traumatic event and risk for PTSD are discussed. The potential application of an attention bias modification treatment (ABMT) tailored to reduce risk for PTSD is suggested.
Molinism and divine prophecy of free actions
Authors: OPPY GRAHAM , SAWARD MARK
Published: October 2013

Among challenges to Molinism, the challenge posed by divine prophecy of human free action has received insufficient attention. We argue that this challenge is a significant addition to the array of challenges that confront Molinism.
Geriatric assessment in frail older patients in the emergency department
Authors: Fernández-Alonso Cesáreo , Martín-Sánchez F Javier
Published: October 2013

Emergency care of elderly patients is frequent and complex in the emergency department. Frail older patients have a high risk of poor short-term results following emergency care. There is no practical universal or standardized tool defining frailty. It must be systematically identified in older patients at risk using a screening test, and in those who are positive, a diagnostic scale of frailty or preferably a geriatric scale adapted to emergency care is carried out. An adapted geriatric assessment including brief scales related to clinical, mental, functional and social aspects has been proposed. There are currently no geriatric intervention models with sufficient evidence in frail older patients.
Protecting and expanding the richness and diversity of life, an ethic for astrobiology research and space exploration
Authors: Randolph Richard O. , McKay Christopher P.
Published: October 2013

The ongoing search for life on other worlds and the prospects of eventual human exploration of the Moon and Mars indicate the need for new ethical guidelines to direct our actions as we search and how we respond if we discover microbial life on other worlds. Here we review how life on other worlds presents a novel question in environmental ethics. We propose a principle of protecting and expanding the richness and diversity of life as the basis of an ethic for astrobiology research and space exploration. There are immediate implications for the operational policies governing how we conduct the search for life on Mars and how we plan for human exploration throughout the Solar System.
Birth of an idea: the founding of the International Committee of the Red Cross and of the International Red Cross and Red Crescent Movement: from Solferino to the original Geneva Convention (1859–1864)
Authors: Bugnion François
Published: October 2013

The trauma of coming face to face with the horrors of a battlefield and witnessing first-hand the abandonment of the war-wounded led Henry Dunant to two ingenious concepts: the creation of permanent volunteer relief societies and the adoption of a treaty to protect wounded soldiers and all who endeavour to come to their aid. On the initiative of Gustave Moynier, a committee was established in Geneva to implement Dunant's proposals. That committee – which soon took the name ‘International Committee of the Red Cross’ (ICRC) – convened two international conferences, the first of which laid the foundation for the future relief societies while the second adopted the initial Geneva Convention. This article considers the circumstances that led to the founding of the ICRC and then to that of the International Red Cross and Red Crescent Movement, starting with Solferino and culminating in the adoption of the Geneva Convention.
Cognitive remediation in schizophrenia: background, techniques, evidence of efficacy and perspectives
Authors: Vita A. , Barlati S. , Bellani M. , Brambilla P.
Published: October 2013

Impairment of cognitive functions is a core feature of schizophrenia with relevant consequences on patients' psychosocial functioning. Cognitive remediation techniques have been recently developed with the aim to restore or compensate for such impairments and improve the functional outcome of the disease. There is now convincing evidence of the efficacy of many of these techniques, especially when delivered in the context of a comprehensive treatment programme. Whether the application of these techniques in the early phases of the disease could modify the disease course and outcome and how they could affect brain plasticity and the trajectory of brain disease of schizophrenia is still under scrutiny.
FoxO1 controls lysosomal acid lipase in adipocytes: implication of lipophagy during nutrient restriction and metformin treatment
Authors: Lettieri Barbato D , Tatulli G , Aquilano K , Ciriolo M R
Published: October 2013

Finding new molecular pathways and strategies modulating lipolysis in adipocytes is an attractive goal of the current research. Indeed, it is becoming clear that several human age-related pathologies are caused by adipose tissue expansion and altered lipid metabolism. In the present work, we show that transcription factor forkhead homeobox type protein O1 (FoxO1) is upregulated by nutrient restriction (NR) in adipocytes and exerts the transcriptional control of lipid catabolism via the induction of lysosomal acid lipase (Lipa). An increased autophagy and colocalization of lipid droplets (LDs) with lysosomes was observed implying lipophagy in Lipa-mediated LDs degradation. Interestingly, we found that metformin (Metf), a biguanide drug commonly used to treat type-2 diabetes, exerts effects comparable to that of NR. Actually, it was able to elicit FoxO1-dependent Lipa induction as well as LDs degradation through lipophagy. Moreover, we demonstrate that, during NR or Metf treatment, free fatty acids released by Lipa are directed toward AMP-activated protein kinase-mediated mitochondrial oxidation, thus maintaining energetic homeostasis in adipocytes. In conclusion, our data show that lysosomal-mediated lipid catabolism is activated by NR in adipocytes and give further support to the use of Metf as a NR mimetic to combat age-related diseases associated with altered lipid metabolism.
Seasonal variation in the metratranscriptomes of a Thaumarchaeota population from SE USA coastal waters
Authors: Hollibaugh James T , Gifford Scott M , Moran Mary Ann , Ross Meredith J , Sharma Shalabh , Tolar Bradley B
Published: October 2013

We used a combination of metatranscriptomic analyses and quantitative PCR (qPCR) to study seasonal changes in Thaumarchaeota populations from a salt marsh-dominated estuary. Surface waters (0.5 m depth) were sampled quarterly at Marsh Landing, Sapelo Island, GA, USA over a 3-year period. We found a mid-summer peak in Thaumarchaeota abundance measured by qPCR of either 16S rRNA or amoA genes in each of the 3 years. Thaumarchaeota were 100–1000-fold more abundant during the peak than at other times of the year, whereas the abundance of ammonia- and nitrite-oxidizing Bacteria varied <10-fold over the same period. Analysis of the microdiversity of several highly transcribed genes in 20 metatranscriptomes from a 1-year subset of these samples showed that the transcriptionally active population consisted of 2 or 3 dominant phylotypes that differed between successive summers. This shift appeared to have begun during the preceding winter and spring. Transcripts from the same genes dominated the Thaumarchaeota mRNA pool throughout the year, with genes encoding proteins believed to be involved in nitrogen uptake and oxidation, and two hypothetical proteins being the most abundant transcripts in all libraries. Analysis of individual genes over the seasonal cycle suggested that transcription was tied more closely to variation in growth rates than to seasonal changes in environmental conditions. Day–night differences in the relative abundance of transcripts for ribosomal proteins suggested diurnal variation in Thaumarchaeota growth.
Genetic diversity of inorganic carbon uptake systems causes variation in CO2 response of the cyanobacterium Microcystis
Authors: Sandrini Giovanni , Matthijs Hans C P , Verspagen Jolanda M H , Muyzer Gerard , Huisman Jef
Published: October 2013

Rising CO2 levels may act as an important selective factor on the CO2-concentrating mechanism (CCM) of cyanobacteria. We investigated genetic diversity in the CCM of Microcystis aeruginosa, a species producing harmful cyanobacterial blooms in many lakes worldwide. All 20 investigated Microcystis strains contained complete genes for two CO2 uptake systems, the ATP-dependent bicarbonate uptake system BCT1 and several carbonic anhydrases (CAs). However, 12 strains lacked either the high-flux bicarbonate transporter BicA or the high-affinity bicarbonate transporter SbtA. Both genes, bicA and sbtA, were located on the same operon, and the expression of this operon is most likely regulated by an additional LysR-type transcriptional regulator (CcmR2). Strains with only a small bicA fragment clustered together in the phylogenetic tree of sbtAB, and the bicA fragments were similar in strains isolated from different continents. This indicates that a common ancestor may first have lost most of its bicA gene and subsequently spread over the world. Growth experiments showed that strains with sbtA performed better at low inorganic carbon (Ci) conditions, whereas strains with bicA performed better at high Ci conditions. This offers an alternative explanation of previous competition experiments, as our results reveal that the competition at low CO2 levels was won by a specialist with only sbtA, whereas a generalist with both bicA and sbtA won at high CO2 levels. Hence, genetic and phenotypic variation in Ci uptake systems provide Microcystis with the potential for microevolutionary adaptation to changing CO2 conditions, with a selective advantage for bicA-containing strains in a high-CO2 world.
Using environmental niche models to test the ‘everything is everywhere’ hypothesis for Badhamia
Authors: Aguilar María , Fiore-Donno Anna-Maria , Lado Carlos , Cavalier-Smith Thomas
Published: October 2013

It is often discussed whether the biogeography of free-living protists is better explained by the ‘everything is everywhere’(EiE) hypothesis, which postulates that only ecology drives their distribution, or by the alternative hypothesis of ‘moderate endemicity’ in which geographic barriers can limit their dispersal. To formally test this, it would be necessary not only to find organisms restricted to a geographical area but also to check for their presence in any other place with a similar ecology. We propose the use of environmental niche models to generate and test null EiE distributions. Here we have analysed the distribution of 18S rDNA variants (ribotypes) of the myxomycete Badhamia melanospora (belonging to the protozoan phylum Amoebozoa) using 125 specimens from 91 localities. Two geographically structured groups of ribotypes congruent with slight morphological differences in the spores can be distinguished. One group comprises all populations from Argentina and Chile, and the other is formed by populations from North America together with human-introduced populations from other parts of the world. Environmental climatic niche models constructed separately for the two groups have significant differences, but show several overlapping areas. However, only specimens from one group were found in an intensively surveyed area in South America where both niche models overlap. It can be concluded that everything is not everywhere for B. melanospora. This taxon constitutes a complex formed by at least two cryptic species that probably diverged allopatrically in North and South America.
Medication‐Wide Association Studies
Authors: Ryan PB , Madigan D , Stang PE , Schuemie MJ , Hripcsak G
Published: October 2013

Undiscovered side effects of drugs can have a profound effect on the health of the nation, and electronic health‐care databases offer opportunities to speed up the discovery of these side effects. We applied a “medication‐wide association study” approach that combined multivariate analysis with exploratory visualization to study four health outcomes of interest in an administrative claims database of 46 million patients and a clinical database of 11 million patients. The technique had good predictive value, but there was no threshold high enough to eliminate false‐positive findings. The visualization not only highlighted the class effects that strengthened the review of specific products but also underscored the challenges in confounding. These findings suggest that observational databases are useful for identifying potential associations that warrant further consideration but are unlikely to provide definitive evidence of causal effects.

CPT: Pharmacometrics & Systems Pharmacology (2013) 2, e76; doi:10.1038/psp.2013.52; published online 18 September 2013
β-Substituted γ-butyrolactams from mucochloric acid: synthesis of (±)-baclofen and other γ-aminobutyric acids and useful building blocks
Authors: Biswas Kallolmay , Gholap Rajesh , Srinivas Padakanti , Kanyal Sachin , Sarma Koushik Das
Published: October 2013

A method has been developed to generate γ-butyrolactams substituted regioselectively at the β-position using simple and mild conditions starting with mucochloric acid. The method was further extended to synthesize (±)-baclofen and other γ-aminobutyric acids.
A dual-colorimetric signal strategy for DNA detection based on graphene and DNAzyme
Authors: Zhu Xiaoli , Zhang Huihui , Feng Chang , Ye Zonghuang , Li Genxi
Published: October 2013

By employing graphene together with a peroxidase-mimic DNAzyme, a novel strategy with dual-colorimetric signal (signal-off for the precipitate and signal-on for the supernate under centrifugation) is developed for DNA detection.
Stationary flow conditions in pulsed supersonic beams
Authors: Christen Wolfgang
Published: October 2013

We describe a generally applicable method for the experimental determination of stationary flow conditions in pulsed supersonic beams, utilizing time-resolved electron induced fluorescence measurements of high pressure jet expansions of helium. The detection of ultraviolet photons from electronically excited helium emitted very close to the nozzle exit images the valve opening behavior—with the decided advantage that a photon signal is not affected by beam-skimmer and beam-residual gas interactions; it thus allows to conclusively determine those operation parameters of a pulsed valve that yield complete opening. The studies reveal that a “flat-top” signal, indicating constant density and commonly considered as experimental criterion for continuous flow, is insufficient. Moreover, translational temperature and mean terminal flow velocity turn out to be significantly more sensitive in testing for the equivalent behavior of a continuous nozzle source. Based on the widely distributed Even-Lavie valve we demonstrate that, in principle, it is possible to achieve quasi-continuous flow conditions even with fast-acting valves; however, the two prerequisites are a minimum pulse duration that is much longer than standard practice and previous estimates, and a suitable tagging of the appropriate beam segment.
The extended Koopmans' theorem for orbital-optimized methods: Accurate computation of ionization potentials
Authors: Bozkaya Uğur
Published: October 2013

The extended Koopmans' theorem (EKT) provides a straightforward way to compute ionization potentials (IPs) from any level of theory, in principle. However, for non-variational methods, such as Møller–Plesset perturbation and coupled-cluster theories, the EKT computations can only be performed as by-products of analytic gradients as the relaxed generalized Fock matrix (GFM) and one- and two-particle density matrices (OPDM and TPDM, respectively) are required [J. Cioslowski, P. Piskorz, and G. Liu, J. Chem. Phys. 107, 6804 (1997)]. However, for the orbital-optimized methods both the GFM and OPDM are readily available and symmetric, as opposed to the standard post Hartree–Fock (HF) methods. Further, the orbital optimized methods solve the N-representability problem, which may arise when the relaxed particle density matrices are employed for the standard methods, by disregarding the orbital Z-vector contributions for the OPDM. Moreover, for challenging chemical systems, where spin or spatial symmetry-breaking problems are observed, the abnormal orbital response contributions arising from the numerical instabilities in the HF molecular orbital Hessian can be avoided by the orbital-optimization. Hence, it appears that the orbital-optimized methods are the most natural choice for the study of the EKT. In this research, the EKT for the orbital-optimized methods, such as orbital-optimized second- and third-order Møller–Plesset perturbation [U. Bozkaya, J. Chem. Phys. 135, 224103 (2011)] and coupled-electron pair theories [OCEPA(0)] [U. Bozkaya and C. D. Sherrill, J. Chem. Phys. 139, 054104 (2013)], are presented. The presented methods are applied to IPs of the second- and third-row atoms, and closed- and open-shell molecules. Performances of the orbital-optimized methods are compared with those of the counterpart standard methods. Especially, results of the OCEPA(0) method (with the aug-cc-pVTZ basis set) for the lowest IPs of the considered atoms and closed-shell molecules are substantially accurate, the corresponding mean absolute errors are 0.11 and 0.15 eV, respectively.
Electron cascades in sensors for optical detection of ionizing radiation
Authors: London Richard A. , Lowry Mark E. , Vernon Stephen P. , Stewart Richard E.
Published: October 2013

A new class of high-speed detectors, called RadOptic detectors, measures ionizing radiation incident on a transparent semiconductor by sensing changes in the refractive index with an optical probe beam. We describe the role of radiation-initiated electron cascades in setting the sensitivity and the spatial and temporal resolution of RadOptic detectors. We model electron cascades with both analytical and Monte Carlo computational methods. We find that the timescale for the development of an electron cascade is less than of order 100 fs and is not expected to affect the time response of a detector. The characteristic size of the electron cloud is typically less than 2 μm, enabling high spatial resolution in imaging systems. The electron-hole pair density created by single x-rays is much smaller than the saturation density and, therefore, single events should not saturate the detector.
Non-stationary excitation of two localized spin-wave modes in a nano-contact spin torque oscillator
Authors: Consolo G. , Finocchio G. , Siracusano G. , Bonetti S. , Eklund A. , Åkerman J. , Azzerboni B.
Published: October 2013

We measure and simulate micromagnetically a framework based upon a nano-contact spin torque oscillator where two distinct localized evanescent spin-wave modes can be detected. The resulting frequency spectrum is composed by two peaks, corresponding to the excited modes, which lie below the ferromagnetic resonance frequency, and a low-frequency tail, which we attribute to the non-stationary switching between these modes. By using Fourier, wavelet, and Hilbert-Huang transforms, we investigate the properties of these modes in time and spatial domains, together with their spatial distribution. The existence of an additional localized mode (which was neither predicted by theory nor by previous numerical and experimental findings) has to be attributed to the large influence of the current-induced Oersted field strength which, in the present setup, is of the same order of magnitude as the external field. As a further consequence, the excited spin-waves, contrarily to what usually assumed, do not possess cylindrical symmetry: the Oersted field induces these modes to be excited at the two opposite sides of the region beneath the nano-contact.
Six-dimensional and seven-dimensional quantum dynamics study of the OH + CH4 → H2O + CH3 reaction
Authors: Song Hongwei , Lee Soo-Ying , Yang Minghui , Lu Yunpeng
Published: October 2013

The reaction dynamics of hydroxyl radical with methane has been investigated using time-dependent wave packet approach within reduced six- and seven-dimensional models. Initial state-selected total reaction probabilities and integral cross sections for the hydrogen abstraction reaction have been computed on the empirical potential energy surface developed by Espinosa-García et al. [J. Chem. Phys. 112, 5731 (2000)]. Excitations of the CH stretching mode and/or the CH3 umbrella mode enhance the reaction. They are, however, both less efficient than translational energy in promoting the reaction, at least at low collision energies. Also, we studied the accuracy of two approximations: centrifugal sudden (CS) and J-shifting (JS), in the calculations of the integral cross sections by a comparison to coupled-channel (CC) calculations. The integral cross sections obtained indicated that the CS approximation works well over the whole energy range studied, and the JS approximation gives accurate cross sections at low collision energies, while noticeably overestimates them at relatively high collision energies. In addition, the OH radical acts as a good spectator as it has a negligible effect on the reaction.
The scaling and universality of conventional and inverse magnetocaloric effects in Heusler alloys
Authors: Biswas Anis , Phan T. L. , Dan N. H. , Zhang P. , Yu S. C. , Srikanth H. , Phan M. H.
Published: October 2013

We report a comparative study of the universal behaviors of conventional and inverse magnetocaloric effects (CMCE and IMCE, respectively) that coexist in Heusler alloys of Ni50Mn50−xSnx (x ∼ 13, 14) and Ni50−xPrxMn37Sn13 (x ∼ 1, 3). In contrast to CMCE associated with a first-order phase transition (FOPT), we show that it is possible to construct a universal master curve to describe the temperature dependence of magnetic entropy change ΔSM(T) in different applied fields without rescaling the temperature axis for IMCE associated with FOPT. This universal behavior is shown to be different from that observed for CMCE associated with a second-order phase transition. The proposed universal curves provide an effective method of extrapolating ΔSM of materials associated with CMCE and IMCE in any range of temperatures and magnetic fields, giving useful guidance on the development of active magnetic refrigerants.
Resolution-enhanced polarization imaging with focused thermal pulses
Authors: Aryal Saurav , Mellinger Axel
Published: October 2013

The non-destructive measurement of electrical polarization and space charge densities is a key technique in electret research. The principal idea behind these methods is a non-uniform deformation or heating, which gives rise to a short-circuit current that can be recorded in the time or frequency domain, and which carries information about the polarization depth profile. In recent years, thermal pulses and thermal waves have been used successfully to obtain three-dimensional polarization maps in polymeric electrets by scanning the beam of a pulsed or intensity-modulated cw laser across the sample surface. However, the polarization maps in these experiments were reconstructed using a relatively simplistic one-dimensional heat diffusion model that does not take into account lateral heat diffusion in the metal electrode. A two-dimensional “coupled neighbors” model was developed, where the current signal from several adjacent beam pointings along a scan line is coupled together, and a Monte Carlo method is used for the deconvolution. Simulations show that the new approach enhances the lateral resolution by a factor of 2−3×, since it avoids the information loss occurring when three-dimensional polarization measurements are processed with a one-dimensional thermal model. We also present an augmented, low-noise thermal-pulse instrument where thermal pulses are initiated by a pulse-modulated diode laser.
Laser-seeded modulation instability in a proton driver plasma wakefield accelerator
Authors: Siemon Carl , Khudik Vladimir , Austin Yi S. , Pukhov Alexander , Shvets Gennady
Published: October 2013

A new method for initiating the modulation instability (MI) of a proton beam in a proton driver plasma wakefield accelerator using a short laser pulse preceding the beam is presented. A diffracting laser pulse is used to produce a plasma wave that provides a seeding modulation of the proton bunch with the period equal to that of the plasma wave. Using the envelope description of the proton beam, this method of seeding the MI is analytically compared with the earlier suggested seeding technique that involves an abrupt truncation of the proton bunch. The full kinetic simulation of a realistic proton bunch is used to validate the analytic results. It is further used to demonstrate that a plasma density ramp placed in the early stages of the laser-seeded MI leads to its stabilization, resulting in sustained accelerating electric fields (of order several hundred MV/m) over long propagation distances (∼100–1000 m).