bluuebunny/crossref_metadata_2025 huggingface dataset:
Transient self-focusing of an intense laser pulse in magnetized plasmas under non-paraxial approximation
Authors: Gupta D.N. , Avinash K. , Suk H.
Published: May 2013

Non-paraxial approximation based study of transient self-focusing of an intense short-pulse laser in plasma has been investigated by considering the effect of a transverse magnetic field. The laser with non-uniform distribution of intensity exerts a ponderomotive force on electrons and sets in an ambi-polar diffusion of the plasma. The ambient magnetic field, however, strongly inhibits the process, when the electron Larmor radius is comparable to or shorter than the laser spot size. As the plasma density is depleted, the laser beam becomes more self-focused. This study addresses a significant enhancement in the laser self-focusing rate by including the correction terms due the off-axis approximation.
A Randomized Controlled Trial of the Effectiveness of Computer-Assisted Cognitive Remediation (CACR) in Adolescents with Psychosis or at High Risk of Psychosis
Authors: Holzer Laurent , Urben Sebastien , Passini Christina Moses , Jaugey Laure , Herzog Michael H. , Halfon Olivier , Pihet Sandrine
Published: May 2013

Background: Computer assisted cognitive remediation (CACR) was demonstrated to be efficient in improving cognitive deficits in adults with psychosis. However, scarce studies explored the outcome of CACR in adolescents with psychosis or at high risk. Aims: To investigate the effectiveness of a computer-assisted cognitive remediation (CACR) program in adolescents with psychosis or at high risk. Method: Intention to treat analyses included 32 adolescents who participated in a blinded 8-week randomized controlled trial of CACR treatment compared to computer games (CG). Cognitive abilities, symptoms and psychosocial functioning were assessed at baseline and posttreatment. Results: Improvement in visuospatial abilities was significantly greater in the CACR group than in CG. Other cognitive functions, psychotic symptoms and psychosocial functioning improved significantly, but at similar rates, in the two groups. Conclusion: CACR can be successfully administered in this population; it proved to be effective over and above CG for the most intensively trained cognitive ability.
Afterword: Welfare State Reform, Recognition and Emotional Labor
Authors: Hochschild Arlie
Published: May 2013

In this themed section, the editors and authors take us far beyond the usual thinking about welfare reform. How, they ask, do politicians want us to feel about welfare reform? How do we think we should feel and how do we feel about it? How does the disabled woman who has lost her government-provided caregiver and ‘hasn't been out of the house since Christmas’, feel about it? Or the man who petitions to restore his lost government aid – but fails to do so? Or the wealthy Dutch tax payer? These are are the sorts of questions that arise in the study of a changing welfare states.
New Design for a Versatile Field Microscope
Authors: Goren Yuval
Published: May 2013

The present article presents a new concept for a light optical field microscope developed after two decades of attempts to find a portable, yet versatile and capable, instrument for extra-laboratory research. Emphasis was put on a portable microscope with polarizing capabilities, yet versatile enough to perform in other configurations. After testing almost every available model made during the last century, the Goren microscope, as it is called now, was developed and tested in various field conditions. The new design, fashioned as two prototypes, is expected to be inexpensive if commercially produced. Still, it can be readily modified to perform as a bright-field, dark-field, phase-contrast, or polarizing instrument. The historical background of field microscopes is briefly presented in context of this new invention.
NetNotes
Authors: Phillips Thomas E.
Published: May 2013

Selected postings from the Microscopy Listserver from January 1, 2012 to February 28, 2012. Complete listings and subscription information can be obtained at http://www.microscopy.com. Postings may have been edited to conserve space or for clarity.
Progress in Microanalysis
Authors: Lyman Charles
Published: May 2013

Many researchers view microanalysis as the determination of composition and structure of individual phases at a spatial resolution of 1 μm or better. It is remarkable to me that much of what we know about the phases shown in equilibrium phase diagrams was determined using bulk analysis techniques like powder X-ray diffraction in combination with light microscopy of flat-polished sections of materials. The identities and amounts of phases were deduced from systematic experiments because there was no way to analyze micrometer-sized phases in situ.
Transmission EBSD in the Scanning Electron Microscope
Authors: Geiss Roy H. , Rice Katherine P. , Keller Robert R.
Published: May 2013

We demonstrate in this article an exciting new method for obtaining electron Kikuchi diffraction patterns in transmission from thin specimens in a scanning electron microscope (SEM) fitted with a conventional electron backscattered diffraction (EBSD) detector. We have labeled the method transmission EBSD (t-EBSD) because it uses off-the-shelf commercial EBSD equipment to capture the diffraction patterns and also to differentiate it from transmission Kikuchi diffraction available in the transmission electron microscope (TEM). Lateral spatial resolution of less than 10 nm has been demonstrated for particles and better than 5 nm for orientation mapping of thin films. The only new requirement is a specimen holder that allows the transmitted electrons diffracted from an electron transparent sample to intersect the EBSD detector. We briefly outline our development of the technique, followed by descriptions of sample preparation techniques and operating conditions. We then present examples of t-EBSD patterns from a variety of specimens, including particles of diameter <10 nm, wires of diameter <80 nm, and films with thicknesses from ~5 nm to 300 nm. Finally, we discuss the phenomenon in the context of Monte Carlo electron scattering simulations.
Equipment Funding Opportunities and Strategies for Success (Part 5)
Authors: Henderson Craig
Published: May 2013

As I have been listening to the previous speakers, I have been thinking through my slides. We easily could talk about the Major Research Instrumentation (MRI) program for an hour. So during my time, I will run through the rules of road and things you can do to increase your chances of success and the caveats that go with that. My big take-home message is that this is not something where you can just read the MRI solicitation beforehand and write a good proposal. You really have to think about this and do your homework. Get to know program officers and understand the program. I will try to show you enough of the nuances of the program so that it will encourage you to do that. I'll show you some of the pitfalls, and you'll be able to see you need more information. We're in Arlington, VA, and the old-fashioned way to do this was to go visit us in the NSF building; however we have technology to do that now. We have websites, webcasts (one will be held in December), phone calls, etc. There are a lot of ways to electronically reach out and get information.
Fetuin-A mRNA expression is elevated in NASH compared with NAFL patients
Authors: Kahraman Alisan , Sowa Jan-Peter , Schlattjan Martin , Sydor Svenja , Pronadl Martin , Wree Alexander , Beilfuss Anja , Kilicarslan Alpaslan , Altinbaş Akif , Bechmann Lars Peter , Syn Wing-Kin , Gerken Guido , Canbay Ali
Published: May 2013

Fetuin-A is a pro-inflammatory protein expressed by hepatocytes. Its course in morbidly obese patients with NAFLD (non-alcoholic fatty liver disease) following weight loss by BAS (bariatric surgery) has not been fully elucidated yet. In the present study, we prospectively examined the effects of weight loss on various metabolic factors at 4 weeks and 6 months after surgery. Blood and liver tissues were retrieved from 108 morbidly obese NAFLD patients before/during BAS, and 50 of these individuals met the criteria for NASH (non-alcoholic steatohepatitis). Fetuin-A expression was measured by qPCR (quantitative real-time PCR), Western blotting and immunohistochemistry. Hepatocyte apoptosis was quantified via M30 (caspase-cleaved cytokeratin-18 fragments). Plasma concentrations of adiponectin and fetuin-A were determined by ELISA. Serum-derived parameters were additionally taken at 4 weeks and 6 months post-operatively. In addition, primary human hepatocytes were treated with NEFA (non-esterified fatty acid) to investigate changes in fetuin-A. BMI (body mass index) decreased significantly from 53.0±1.1 to 36.4±1.9 kg/m2 in the NAFL group and from 53.3±1.1 to 37.6±1.2 kg/m2 in the NASH group (P<0.0001) at 6 months post-surgery. This was associated with diminishing M30 and M65 (total cytokeratin-18) levels over 6 months after surgery. Adiponectin levels increased continuously in NASH patients, whereas NAFL patients plateaued at 4 weeks post-operatively. Hepatic fetuin-A mRNA and protein expression was elevated before surgery-induced weight loss. However, plasma concentrations of fetuin-A increased signficantly in NASH patients 4 weeks post-operatively. Treatment of hepatocytes with NEFA led to up-regulation of fetuin-A expression. BAS probably has a beneficial effect on NAFLD, as indicated by reduced hepatocyte apoptosis and improved adipokine profiles. In addition, fetuin-A expression is more prominent in NASH.
Classification Accuracy of Nonword Repetition When Used With Preschool-Age Spanish-Speaking Children
Authors: Guiberson Mark , Rodríguez Barbara L.
Published: May 2013

Purpose

The purpose of the present study was to (a) describe and compare the nonword repetition (NWR) performance of preschool-age Spanish-speaking children (3- to 5-year-olds) with and without language impairment (LI) across 2 scoring approaches and (b) to contrast the classification accuracy of a Spanish NWR task when item-level and percentage of phonemes correct (PPC) scoring methods are applied.

Method

Forty-four Spanish-speaking children participated. Twenty-one children had LI and 23 had typically developing (TD) language. Children were administered a Spanish NWR task and a standardized Spanish language measure.

Results

A developmental pattern in NWR performance was observed, and the children with LI had NWR scores that were significantly lower than those of the TD children. Whereas item-level scoring of NWR items indicated acceptable levels of sensitivity and specificity and suggested positive and negative likelihood ratios, PPC scoring of NWR items resulted in less than desirable levels of sensitivity and adequate specificity.

Conclusion

Item-level scoring of 3- to 5-syllable Spanish NWR items may be useful as part of an assessment battery for preschool-age Spanish-speaking children.
Utility of Stereolithographic Models in Osteocutaneous Free Flap Reconstruction of the Head and Neck
Authors: Morris L. , Sokoya Mofiyinfolu , Cunningham Larry , Gal Thomas J.
Published: May 2013

Background

Stereolithographic (SLA) models have become a valuable resource in preoperative planning in maxillofacial reconstruction. The objective of this study was to perform a defect specific analysis of the utility of SLA models. The goal was to determine the manner in which the perceived benefit of preoperative modeling translates to measurable clinical advantages.

Methods

Patients who underwent reconstruction of defects of the mandible or midface using SLA modeling between 2006 and 2011 were identified through billing records. Based on the nature and extent of bony defect, cases requiring nearly identical reconstruction, but without modeling, were matched case by case for comparison. Given the presumed efficiency of SLA modeling, a comparison of total and reconstructive operative times was performed to see if this could offset the cost of the model.

Results

There were 10 patients each in the “model” and “nonmodel” group. No significant differences were observed for total operative time between groups. Surprisingly, the total reconstructive time was lower in the group not using SLA models ( p = 0.05).

Conclusions

SLA models provide several operative planning advantages, but did not appear to decrease operative time enough to sufficiently offset the cost of the model in this group.
China prepares to spend billions on science and technology
Authors: Feder Toni
Published: May 2013

With its strong economy, the country wants to play a bigger role on the world science stage.
Carbon capture may be a ways off, but ARPA–E is working on it
Authors: Kramer David
Published: May 2013

Several technologies are aimed at minimizing the cost of removing CO2 during coal burning. But their deployment will require subsidies or a price on carbon emissions.
Reaction of OH radicals with 5-hydroxy-2-pentanone: formation yield of 4-oxopentanal and its OH radical reaction rate constant
Authors: Aschmann Sara M. , Arey Janet , Atkinson Roger
Published: May 2013

Environmental context
Alkanes, major constituents of vehicle exhausts, are emitted to the atmosphere where they react, chiefly by gas-phase reactions with the hydroxyl radical, to form products which can also react further. In laboratory experiments, we studied the further reactions of a model first-generation alkane reaction product. Understanding alkane reaction chains is important because the toxicity, secondary aerosol formation and other properties of vehicle emissions can change as new compounds are formed.

Abstract
1,4-Hydroxycarbonyls are major products of the gas-phase reactions of alkanes with OH radicals, and in the atmosphere they will react with OH radicals or undergo acid-catalysed cyclisation with subsequent dehydration to form highly reactive dihydrofurans. 3-Oxobutanal (CH3C(O)CH2CHO) and 4-oxopentanal (CH3C(O)CH2CH2CHO) are first-generation products of the OH radical-initiated reaction of 5-hydroxy-2-pentanone (CH3C(O)CH2CH2CH2OH). The behaviours of 3-oxobutanal and 4-oxopentanal have been monitored during OH+5-hydroxy-2-pentanone reactions carried out in the presence of NO, using solid phase microextraction fibres coated with O-(2,3,4,5,6,-pentafluorobenzyl)hydroxyl amine (PFBHA) for on-fibre derivatisation of carbonyl compounds and an annular denuder coated with XAD resin and further coated with PFBHA. The time-concentration data for 4-oxopentanal during OH+5-hydroxy-2-pentanone reactions were independent of relative humidity (0–50%), and were consistent with a rate constant for OH+4-oxopentanal of (1.2±0.5)×10–11cm3 molecule–1s–1 at 296±2K, a factor of 2 lower than both literature rate constants for other aldehydes and that estimated using a structure-reactivity approach. The molar formation yield for 4-oxopentanal from OH+5-hydroxy-2-pentanone in the presence of NO was determined to be 17±5%, consistent with predictions based on a structure-reactivity relationship and current knowledge of the subsequent reaction mechanisms.
Fast neurotransmitter release regulated by the endocytic scaffold intersectin
Authors: Sakaba Takeshi , Kononenko Natalia L. , Bacetic Jelena , Pechstein Arndt , Schmoranzer Jan , Yao Lijun , Barth Holger , Shupliakov Oleg , Kobler Oliver , Aktories Klaus , Haucke Volker
Published: May 2013

Sustained fast neurotransmission requires the rapid replenishment of release-ready synaptic vesicles (SVs) at presynaptic active zones. Although the machineries for exocytic fusion and for subsequent endocytic membrane retrieval have been well characterized, little is known about the mechanisms underlying the rapid recruitment of SVs to release sites. Here we show that the Down syndrome-associated endocytic scaffold protein intersectin 1 is a crucial factor for the recruitment of release-ready SVs. Genetic deletion of intersectin 1 expression or acute interference with intersectin function inhibited the replenishment of release-ready vesicles, resulting in short-term depression, without significantly affecting the rate of endocytic membrane retrieval. Acute perturbation experiments suggest that intersectin-mediated vesicle replenishment involves the association of intersectin with the fissioning enzyme dynamin and with the actin regulatory GTPase CDC42. Our data indicate a role for the endocytic scaffold intersectin in fast neurotransmitter release, which may be of prime importance for information processing in the brain.
Juvenile hormone and its receptor, methoprene-tolerant, control the dynamics of mosquito gene expression
Authors: Zou Zhen , Saha Tusar T. , Roy Sourav , Shin Sang Woon , Backman Tyler W. H. , Girke Thomas , White Kevin P. , Raikhel Alexander S.
Published: May 2013

Significance

Mosquitoes transmit some of the most dangerous human diseases. Microarray analysis of developmental gene dynamics in the femaleAedes aegyptifat body has demonstrated that 6,146 genes are differentially expressed during juvenile hormone-dependent posteclosion development. These genes show striking temporal and functional separation. A RNAi microarray screen revealed a differential action of Met in the down- and up-regulation of genes expressed during early and late PE, respectively. Thus, this study provides substantial evidence of a central role for insect-specific JH and its receptor Met in the regulation of female mosquito reproductive biology.
The production of a new Eurasian capital on the Kazakh steppe: Architecture, urban design, and identity in Astana
Authors: Köppen Bernhard
Published: May 2013

In December 1997, the Republic of Kazakhstan officially proclaimed that the city of Astana would be its new capital. The decision to transfer the seat of government from the city of Almaty in the south to the more centrally located Astana was connected to the process of nation building in a multi-ethnic society where the titular nation represents little more than half of the population. Efforts to transform the rather remote regional center, Akmola (later renamed Astana) into a modern capital city have been underway since the late 1990s. One important component of this transformation is the idea of building a “metabolic” and sustainable “Eurasian” city. As the symbolic center of the whole country, this new capital would function as a showpiece of Kazakh culture and identity. The city would also become a symbol of economic prosperity and the regime's geopolitical vision. While the government's intensions are expressed rather openly, it remains unclear to what extent these politically verbalized leitmotivs are actually being realized through contemporary architecture and structure. This article offers a critical assessment of what has been achieved to date and argues that the production of the new Kazakhstani capital has often failed to translate rhetoric into reality.
Anglo-Saxon anthropology in Morocco: evaluating Gellner’s segmentary theory
Authors: Masbah Mohammed
Published: May 2013

The 1960s and 1970s presented fertile soil for a number of anthropological theories in Morocco. Those theories tried to offer explanatory paradigms for societies that had just shaken off colonization, especially in Anglo-Saxon studies. Segmentary theory, as part of this tradition, should be understood within the dichotomy of continuity and rupture in theoretical contributions on Morocco; its roots derive from both Khaldunian and colonial thought. Ernest Gellner’s work on the Saints of the Atlas (1969) is considered among the most interesting studies that applied segmentary theory to understand Moroccan society in the post-independence era. In fact, much criticism has been levelled at this theory from different researchers such as Jacque Berque, Paul Pascon, Abdelkbir Khatibi, Abdellah Hammoudi, Abdellah Laroui and Mokhtar Harras, among others. Criticism mainly focused on the ideological and ethnocentric background that frames the frozen starting arguments of the segmentary approach. It maintains that ‘pre-capitalist’ societies were static, had no history and could not produce but social orders and intellectual and economic institutions that exalt loyalty to community and the authority of customs and ancestry, while they lacked power centralization, would reproduce themselves routinely and statically as well as diminish the prospects of social change. This paper criticizes Gellner’s segmentary theory for neglecting the role of kinship and blood ties, social stratification and chiefship, marginalizing socio-historical dynamics, and the overemphasizing of the pacific role of religion and saints.
What changes have taken place in US foreign policy towards Islamists?
Authors: Gerges Fawaz A.
Published: May 2013

American foreign policy does not seem to have undergone radical changes in its position towards Islamists. Instead, Islamists seem to display willingness to make a transition and cater for vital American interests in the Arab world - mainly with regard to the following four points: political economy; relations with Israel; the War on Terror; and issues related to identity, especially in the case of minorities. Islamists appear to have proven malleability towards the US in relation to the economic system and foreign policy. Some Islamist leaders have pointed out that the price of this adaptability is expected to be the respect of the US for Islamic ethos, added to the Islamists’ autonomy on domestic, social and cultural issues. In conclusion, the relationship between Islamists and the US seems to be in the course of being shaped, but meanwhile, Islamists seem to adopt a realist stand on American foreign policy and national security whereby they do not seem to have quit the approaches of those regimes that have just gone.
Novel criteria for exponential stability of functional differential equations
Authors: Ngoc Pham
Published: May 2013

We first give explicit criteria for exponential stability of general linear nonautonomous functional differential equations. Then the obtained results are extended to nonlinear functional differential equations. Two examples are given to illustrate the results. To the best of our knowledge, the results of this note are new.
Authenticity in Early Childhood Assessment
Authors: Macy Marisa , Bagnato Steven J.
Published: May 2013

Conventional tests and testing practices are at odds with professional “best practice” standards in early childhood intervention. Moreover, conventional tests have been neither developed for nor field-validated on young children with disabilities for early intervention purposes. Dramatic changes are emerging in the assessment of young children, particularly those with developmental delays/disabilities. Interdisciplinary professionals must know and adhere to the professional practice standards for assessment in early childhood intervention. The National Association for the Education of Young Children (NAEYC) and the Division for Early Childhood (DEC) standards promote authentic assessment as the evidence-based alternative for young children to prevent the misrepresentation of young children with disabilities—the mismeasure of young children (Bagnato, Neisworth & Pretti-Frontczak, 2010).
Medicago truncatula esn1 Defines a Genetic Locus Involved in Nodule Senescence and Symbiotic Nitrogen Fixation
Authors: Xi Jiejun , Chen Yuhui , Nakashima Jin , Wang Suo-min , Chen Rujin
Published: May 2013

Symbiotic interaction between Medicago truncatula and Sinorhizobium meliloti results in the formation on the host roots of new organs, nodules, in which biological nitrogen fixation takes place. In infected cells, rhizobia enclosed in a plant-derived membrane, the symbiosome membrane, differentiate to nitrogen-fixing bacteroids. The symbiosome membrane serves as an interface for metabolite and signal exchanges between the host cells and endosymbionts. At some point during symbiosis, symbiosomes and symbiotic cells are disintegrated, resulting in nodule senescence. The regulatory mechanisms that underlie nodule senescence are not fully understood. Using a forward genetics approach, we have uncovered the early senescent nodule 1 (esn1) mutant from an M. truncatula fast neutron-induced mutant collection. Nodules on esn1 roots are spherically shaped, ineffective in nitrogen fixation, and senesce early. Atypical among fixation defective mutants isolated thus far, bacteroid differentiation and expression of nifH, Leghemoglobin, and DNF1 genes are not affected in esn1 nodules, supporting the idea that a process downstream of bacteroid differentiation and nitrogenase gene expression is affected in the esn1 mutant. Expression analysis shows that marker genes involved in senescence, macronutrient degradation, and remobilization are greatly upregulated during nodule development in the esn1 mutant, consistent with a role of ESN1 in nodule senescence and symbiotic nitrogen fixation.
Identification of Plasmopara viticola Genes Potentially Involved in Pathogenesis on Grapevine Suggests New Similarities Between Oomycetes and True Fungi
Authors: Luis P. , Gauthier A. , Trouvelot S. , Poinssot B. , Frettinger P.
Published: May 2013

Plant diseases caused by fungi and oomycetes result in significant economic losses every year. Although phylogenetically distant, these organisms share many common features during infection. We identified genes in the oomycete Plasmopara viticola that are potentially involved in pathogenesis in grapevine by using fungal databases and degenerate primers. Fragments of P. viticola genes encoding NADH-ubiquinone oxidoreductase (PvNuo), laccase (PvLac), and invertase (PvInv) were obtained. PvNuo was overexpressed at 2 days postinoculation (dpi), during the development of the first hyphal structures and haustoria. PvLac was overexpressed at 5 dpi when genes related to pterostilbene biosynthesis were induced in grapevine. Transcript level for PvInv increased between 1 and 4 dpi before reaching a plateau. These results might suggest a finely tuned strategy of infection depending on nutrition and plant response. Phylogenetic analyses of PvNuo showed that P. viticola clustered with other oomycetes and was associated with brown algae and diatoms, forming a typical Straminipila clade. Based on the comparison of available sequences for laccases and invertases, the group formed by P. viticola and other oomycetes tended to be more closely related to Opisthokonta than to Straminipila. Convergent evolution or horizontal gene transfer could explain the presence of fungus-like genes in P. viticola.
Fabrication and
in vitro
evaluation of stable collagen/hyaluronic acid biomimetic multilayer on titanium coatings
Authors: Ao Haiyong , Xie Youtao , Tan Honglue , Yang Shengbing , Li Kai , Wu Xiaodong , Zheng Xuebin , Tang Tingting
Published: May 2013

Layer-by-layer (LBL) self-assembly technique has been proved to be a highly effective method to immobilize the main components of the extracellular matrix such as collagen and hyaluronic acid on titanium-based implants and form a polyelectrolyte multilayer (PEM) film by electrostatic interaction. However, the formed PEM film is unstable in the physiological environment and affects the long-time effectiveness of PEM film. In this study, a modified LBL technology has been developed to fabricate a stable collagen/hyaluronic acid (Col/HA) PEM film on titanium coating (TC) by introducing covalent immobilization. Scanning electron microscopy, diffuse reflectance Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were used to characterize the PEM film. Results of Sirius red staining demonstrated that the chemical stability of PEM film was greatly improved by covalent cross-linking. Cell culture assays further illustrated that the functions of human mesenchymal stem cells, such as attachment, spreading, proliferation and differentiation, were obviously enhanced by the covalently immobilized Col/HA PEM on TCs compared with the absorbed Col/HA PEM. The improved stability and biological properties of the Col/HA PEM covalently immobilized TC may be beneficial to the early osseointegration of the implants.
Stochastic transitions in a bistable reaction system on the membrane
Authors: Kochańczyk Marek , Jaruszewicz Joanna , Lipniacki Tomasz
Published: May 2013

Transitions between steady states of a multi-stable stochastic system in the perfectly mixed chemical reactor are possible only because of stochastic switching. In realistic cellular conditions, where diffusion is limited, transitions between steady states can also follow from the propagation of travelling waves. Here, we study the interplay between the two modes of transition for a prototype bistable system of kinase–phosphatase interactions on the plasma membrane. Within microscopic kinetic Monte Carlo simulations on the hexagonal lattice, we observed that for finite diffusion the behaviour of the spatially extended system differs qualitatively from the behaviour of the same system in the well-mixed regime. Even when a small isolated subcompartment remains mostly inactive, the chemical travelling wave may propagate, leading to the activation of a larger compartment. The activating wave can be induced after a small subdomain is activated as a result of a stochastic fluctuation. Such a spontaneous onset of activity is radically more probable in subdomains characterized by slower diffusion. Our results show that a local immobilization of substrates can lead to the global activation of membrane proteins by the mechanism that involves stochastic fluctuations followed by the propagation of a semi-deterministic travelling wave.
Mesenchymal stem cell mechanobiology and emerging experimental platforms
Authors: MacQueen Luke , Sun Yu , Simmons Craig A.
Published: May 2013

Experimental control over progenitor cell lineage specification can be achieved by modulating properties of the cell's microenvironment. These include physical properties of the cell adhesion substrate, such as rigidity, topography and deformation owing to dynamic mechanical forces. Multipotent mesenchymal stem cells (MSCs) generate contractile forces to sense and remodel their extracellular microenvironments and thereby obtain information that directs broad aspects of MSC function, including lineage specification. Various physical factors are important regulators of MSC function, but improved understanding of MSC mechanobiology requires novel experimental platforms. Engineers are bridging this gap by developing tools to control mechanical factors with improved precision and throughput, thereby enabling biological investigation of mechanics-driven MSC function. In this review, we introduce MSC mechanobiology and review emerging cell culture platforms that enable new insights into mechanobiological control of MSCs. Our main goals are to provide engineers and microtechnology developers with an up-to-date description of MSC mechanobiology that is relevant to the design of experimental platforms and to introduce biologists to these emerging platforms.
Purification of Rat and Mouse Astrocytes by Immunopanning
Authors: Foo Lynette C.
Published: May 2013

We describe the use of immunopanning to purify rodent astrocytes. Immunopanning of astrocytes permits the prospective isolation of astrocytes from the rodent brain. Prospective isolation refers to the direct selection of cells without multiple steps that extend over a few days, thereby permitting the selection of a representative proportion of the astrocytes from the cortex. Because immunopanning is a very gentle process, the cells are viable at the end of the preparation and can be cultured in a serum-free medium containing heparin-binding EGF-like growth factor (HBEGF), the critical survival factor of astrocytes in vitro, for at least 2 wk. This protocol was initially established and verified with rats, but modifications for the purification of mouse cells are also described here.
Preparation of 32P-End-Labeled DNA Fragments for Performing DNA-Binding Experiments
Authors: Carey Michael F. , Peterson Craig L. , Smale Stephen T.
Published: May 2013

The generation of a uniquely 32P-end-labeled DNA fragment is essential for DNA-binding experiments such as DNase I footprinting and ethylation interference. We describe here a protocol for end-labeling a restriction fragment. For a plasmid DNA bearing a region containing the binding site of interest, cleaving with a single restriction endonuclease generates a 5′ overhang containing a phosphate. This is generally necessary for both common forms of fragment end-labeling: phosphorylation with polynucleotide kinase and “filling in the end” with DNA polymerases (e.g., Klenow fragment). For the phosphorylation reaction, as described here, the phosphate is removed with calf intestinal phosphatase or bacterial alkaline phosphatase, and the resulting free 5′-OH is phosphorylated with polynucleotide kinase and [γ-32P]ATP. This generates a plasmid labeled at each end with γ-32P. The molar amount of plasmid DNA must be below the amount of ATP added to the reaction and the ATP must be of sufficiently high specific activity to generate a fragment labeled to the extent necessary for many DNA-binding experiments. To generate a uniquely end-labeled DNA fragment, the labeled plasmid is heat-treated to inactivate any remaining kinase and recleaved with a second endonuclease, releasing a short DNA fragment and a longer vector fragment. The DNA fragment is purified from the labeled vector on a 5%–8% native polyacrylamide gel. The preparation and labeling of DNA restriction fragments typically takes 1–2 d.
Introduction of Aequorin into Zebrafish Embryos for Recording Ca2+ Signaling during the First 48 h of Development
Authors: Webb Sarah E. , Chan Ching Man , Miller Andrew L.
Published: May 2013

Ca2+ signals, whether transient pulses, propagating waves, or long-duration, steady gradients, are generally considered to play an important role in the pattern-forming events that occur during vertebrate development. One vertebrate that has long been a favorite of embryologists because of its ex utero development and the optical clarity of its embryos is the zebrafish, Danio rerio. Using the bioluminescent Ca2+ reporter aequorin, distinct Ca2+ signals have been reported for at least the first 48 h of zebrafish development, with signals becoming progressively more complex as the embryo develops. Here we provide a general introduction to aequorin and its use in monitoring Ca2+ signals and discuss methods for introducing aequorin into zebrafish embryos.
Estimating Length in Biological Structures
Authors: West Mark J.
Published: May 2013

Length estimates of particular features of biological tissues can be useful in evaluating function. Such estimates have been notoriously difficult to obtain because of the requirement for an isotropic interaction between the area probes and the linear features of cells and tissues, which are most likely not isotropically oriented. For complex embedded structures, such as subdivisions of the brain, the turning of the tissue before sectioning that is needed to ensure an isotropic interaction has made it difficult to delineate many regions of interest and limited the number of unbiased stereological studies of length. The recent development of a virtual isotropic spherical probe, the spaceball, makes it relatively easy for the isotropic interaction between probe and structure to be realized. This article describes the use of the spaceball probe to estimate length, and gives an example of estimating total capillary length in CA1 stratum radiatum of the human hippocampus.
EMBRYONIC FLOWER1 and ULTRAPETALA1 Act Antagonistically on Arabidopsis Development and Stress Response
Authors: Pu Li , Liu Mao-Sen , Kim Sang Yeol , Chen Long-Fang O. , Fletcher Jennifer C. , Sung Zinmay Renee
Published: May 2013

Epigenetic regulation of gene expression is of fundamental importance for eukaryotic development. EMBRYONIC FLOWER1 (EMF1) is a plant-specific gene that participates in Polycomb group-mediated transcriptional repression of target genes such as the flower MADS box genes AGAMOUS, APETALA3, and PISTILLATA. Here, we investigated the molecular mechanism underlying the curly leaf and early flowering phenotypes caused by reducing EMF1 activity in the leaf primordia of LFYasEMF1 transgenic plants and propose a combined effect of multiple flower MADS box gene activities on these phenotypes. ULTRAPETALA1 (ULT1) functions as a trithorax group factor that counteracts Polycomb group action in Arabidopsis (Arabidopsis thaliana). Removing ULT1 activity rescues both the abnormal developmental phenotypes and most of the misregulated gene expression of LFYasEMF1 plants. Reducing EMF1 activity increases salt tolerance, an effect that is diminished by introducing the ult1-3 mutation into the LFYasEMF1 background. EMF1 is required for trimethylating lysine-27 on histone 3 (H3K27me3), and ULT1 associates with ARABIDOPSIS TRITHORAX1 (ATX1) for trimethylating lysine-3 on histone 4 (H3K4me3) at flower MADS box gene loci. Reducing EMF1 activity decreases H3K27me3 marks and increases H3K4me3 marks on target gene loci. Removing ULT1 activity has the opposite effect on the two histone marks. Removing both gene activities restores the active and repressive marks to near wild-type levels. Thus, ULT1 acts as an antirepressor that counteracts EMF1 action through modulation of histone marks on target genes. Our analysis indicates that, instead of acting as off and on switches, EMF1 and ULT1 mediate histone mark deposition and modulate transcriptional activities of the target genes.
N—H...O and N—H...N interactions in three pyran derivatives
Authors: Vishnupriya R. , Suresh J. , Sivakumar S. , Kumar R. Ranjith
Published: May 2013

The three pyran structures 6-methylamino-5-nitro-2,4-diphenyl-4H-pyran-3-carbonitrile, C19H15N3O3, (I), 4-(3-fluorophenyl)-6-methylamino-5-nitro-2-phenyl-4H-pyran-3-carbonitrile, C19H14FN3O3, (II), and 4-(4-chlorophenyl)-6-methylamino-5-nitro-2-phenyl-4H-pyran-3-carbonitrile, C19H14ClN3O3, (III), differ in the nature of the aryl group at the 4-position. The heterocyclic ring in all three structures adopts a flattened boat conformation. The dihedral angle between the pseudo-axial phenyl substituent and the flat part of the pyran ring is 89.97 (1)° in (I), 80.11 (1)° in (II) and 87.77 (1)° in (III). In all three crystal structures, a strong intramolecular N—H...O hydrogen bond links the flat conjugated H—N—C=C—N—O fragment into a six-membered ring. In (II), molecules are linked into dimeric aggregates by N—H... O(nitro) hydrogen bonds, generating anR22(12) graph-set motif. In (III), intermolecular N—H...N and C—H...N hydrogen bonds link the molecules into a linear chain pattern generatingC(8) andC(9) graph-set motifs, respectively.
The ‘dirty dozen’: socio‐economic factors amplify the invasion potential of 12 high‐risk aquatic invasive species in Great Britain and Ireland
Authors: Gallardo Belinda , Aldridge David C.
Published: May 2013

Aquatic invasive species are a growing concern to environmental managers because of their diverse impacts on aquatic biodiversity and high eradication costs, necessitating effective management policies. In this study, we evaluate the ability of environmental and socio‐economic factors to predict the risk of invasion in Great Britain and Ireland of 12 potential aquatic invaders covering all major aquatic groups. Despite their potential to inform risk assessments, this is the first time socio‐economic factors related to propagule pressure have been specifically integrated in distribution modelling.

Species distribution models (SDM, MaxEnt algorithm) were calibrated with a set of environmental factors (e.g. bioclimatic, geographical and geological) and integrated with socio‐economic (e.g. human influence index, population density, closeness to ports) predictors.

The inclusion of socio‐economic factors in SDM did not affect accuracy scores (AUC already >0·90), but their effects were more pronounced in spatial predictions, resulting in up to a sixfold amplification of the area predicted suitable for each species. Despite the inclusion of potential surrogates of water chemistry (e.g. geology) and propagule pressure (e.g. population density), temperature‐related variables were most important predictors of aquatic species' distributions.

According to SDM, the environmental suitability for a suite of invaders belonging to different taxonomic groups and regions of origin is greatest in east and south‐east England and decreases towards the north and west. Multiple invasions in this region are of special concern, as species are known to modify their habitat facilitating subsequent invasions, thereby potentially exacerbating their impacts.

Major management regions to be prioritized in monitoring programmes include the Humber, Thames and Anglian River Basin Districts. Species of special concern include a mysid (Hemimysis anomala), a gammarid (Dikerogammarus villosus), a plant (Ludwigia grandiflora) and two crayfishes (Procambarus clarkii and P. fallax).

Synthesis and Applications. The inclusion of socio‐economic factors in species distribution models has the potential to improve predictions of areas under a highest risk of multiple invasions and to help disentangle the complex interplay between biological invasions and global environmental and socio‐economic processes. Such understanding is pivotal to prioritize limited resources for the optimum prevention and control of biological invasions.
Property as Governance: Time, Space and Belonging in Australia's Northern Territory Intervention
Authors: Keenan Sarah
Published: May 2013

This article analyses two cases brought by aboriginal Australians against the Australian government acquisition of long leases of their land under the Northern Territory National Emergency Response Act 2007. These leases are conspicuous, particularly in that the government always made it clear that it would not take up its right to exclusive possession of the leased land, and has not done so. The leases have not been used to evict residents, as some feared; nor to pursue mining or agricultural activity. Socio‐legal theories centered on the right to exclusive possession cannot account for these leases. The article explores the use of property under the 2007 Act, the legal geographies of the areas subject to the leases and the political potency of property beyond exclusive possession, and suggests an understanding of property as a spatially contingent relation of belonging. Specifically, the article argues that property is productive of temporal and spatial order and so can function as a tool of governance.
Faked Headaches Becoming Real
Authors: Haan Joost
Published: May 2013

In the gangster movie White Heat, the main character, Cody (played by James Cagney), suffers from 2 headache attacks. Here, I analyze these attacks by using the International Headache Society criteria, but an unequivocal diagnosis is not possible. Nevertheless, the attacks play an important role in the narrative and – as representation of something between “real” (mimesis) and not real – provide a ground for reflection on how to think of headache in general.
Destructive Leadership and the Penn State Scandal: A Toxic Triangle Perspective
Authors: Thoroughgood Christian N. , Padilla Art
Published: May 2013

Alderfer's (2013) piece on the Sandusky/Penn State tragedy reminds us that leader-centric analyses, the norm in leadership studies, often miss the mark. Alderfer joins a growing list of writers who increasingly recognize that leadership consists of three key elements in a triangle: leaders, followers, and environments. The Penn State scandal highlights how a conducive environment, typified by centralized power and an absence of checks and balances, coupled with flawed leaders and the actual assistance or quiet submission of certain followers, can lead to disastrous outcomes. As Alderfer observes, leadership is a social, or group, process. Leadership success or failure depends on group results, and group results involve more than just leaders and their characteristics and actions. Yet, over three-quarters of articles in scholarly journals consistently overlook the role of organizational environments and followers (Porter & McLaughlin, 2006), focusing instead on leader traits and behaviors (Kaiser, Hogan, & Craig, 2008; Thoroughgood, Padilla, Hunter, & Tate, 2012).
Not Just Intergroup: The Role of Status Within Groups in the Sandusky Scandal
Authors: Bailey Sarah F. , Ferguson Amanda J.
Published: May 2013

The series of events in the 2011 Penn State sexual abuse scandal were tumultuous and complex. Alderfer's (2013) focal article on the group-level phenomena surrounding the scandal provides a unique lens to view these events. However, questions remain about how relationships both within and between the groups involved in the scandal resulted in these outcomes. In particular, why did members of groups within Penn State fail to act, whereas people who belonged to other social groups took action? In short, we agree that group and intergroup boundaries were important in this situation, but would like to further elaborate on the underlying mechanisms behind their significance. Beyond the fact that individuals belonged to different groups, what aspects of group dynamics explain the differences in their perceptions, attitudes, and behaviors in this scandal?
Integrating Physical Sciences Perspectives in Cancer Research
Authors: Kuhn Nastaran Z. , Nagahara Larry A.
Published: May 2013

Cancer research integrated a physical sciences perspective through team science, which fostered communication, trust, joint publication, and open access to data.
Clostridium difficile Binary Toxin CDT Induces Clustering of the Lipolysis-Stimulated Lipoprotein Receptor into Lipid Rafts
Authors: Papatheodorou Panagiotis , Hornuss Daniel , Nölke Thilo , Hemmasi Sarah , Castonguay Jan , Picchianti Monica , Aktories Klaus
Published: May 2013

Clostridium difficile
is the leading cause of antibiotics-associated diarrhea and pseudomembranous colitis. Hypervirulent
C. difficile
strains produce the binary actin-ADP-ribosylating toxin CDT (
C. difficile
transferase), in addition to the Rho-glucosylating toxins A and B. We recently identified the lipolysis-stimulated lipoprotein receptor (LSR) as the host receptor that mediates uptake of CDT into target cells. Here we investigated in H1-HeLa cells, which ectopically express LSR, the influence of CDT on the plasma membrane distribution of the receptor. We found by fluorescence microscopy that the binding component of CDT (CDTb) induces clustering of LSR into subcompartments of the plasma membrane. Detergent extraction of cells treated with CDTb, followed by sucrose gradient fractionation, uncovered accumulation of LSR in detergent-resistant membranes (DRMs) that contained typical marker proteins of lipid rafts. Membrane cholesterol depletion with methyl-β-cyclodextrin inhibited the association of LSR with DRMs upon addition of CDTb. The receptor-binding domain of CDTb also triggered LSR clustering into DRMs. CDTb-triggered clustering of LSR into DRMs could be confirmed in Caco-2 cells. Our data suggest that CDT forces its receptor to cluster into lipid rafts and that oligomerization of the B component might enhance but is not essential for this process.

IMPORTANCE
C. difficile
binary toxin CDT is a member of the iota-like, actin ADP-ribosylating toxin family. The mechanism that mediates endocytic uptake of these toxins still remains elusive. Previous studies highlighted the importance of lipid rafts for oligomerization of the binding component of these toxins and for cell entry. Recently, the host cell receptor for this toxin family, namely, the lipolysis-stimulated lipoprotein receptor (LSR), has been identified. Our study now demonstrates that the binding component of CDT (CDTb) induces clustering of LSR into lipid rafts. Importantly, LSR clustering is efficiently induced also by the receptor-binding domain of CDTb, suggesting that oligomerization of the B component of CDT is not the main trigger of this process. The current work extends our knowledge on the cooperative play between iota-like toxins and their receptor.