bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhanced Homing Permeability and Retention of Bone Marrow Stromal Cells by Noninvasive Pulsed Focused Ultrasound
Authors: Ziadloo Ali , Burks Scott R. , Gold Eric M. , Lewis Bobbi K. , Chaudhry Aneeka , Merino Maria J. , Frenkel Victor , Frank Joseph A.
Published: April 2012

Bone marrow stromal cells (BMSCs) have shown significant promise in the treatment of disease, but their therapeutic efficacy is often limited by inefficient homing of systemically administered cells, which results in low number of cells accumulating at sites of pathology. BMSC home to areas of inflammation where local expression of integrins and chemokine gradients is present. We demonstrated that nondestructive pulsed focused ultrasound (pFUS) exposures that emphasize the mechanical effects of ultrasound-tissue interactions induced local and transient elevations of chemoattractants (i.e., cytokines, integrins, and growth factors) in the murine kidney. pFUS-induced upregulation of cytokines occurred through approximately 1 day post-treatment and returned to contralateral kidney levels by day 3. This window of significant increases in cytokine expression was accompanied by local increases of other trophic factors and integrins that have been shown to promote BMSC homing. When BMSCs were intravenously administered following pFUS treatment to a single kidney, enhanced homing, permeability, and retention of BMSC was observed in the treated kidney versus the contralateral kidney. Histological analysis revealed up to eight times more BMSC in the peritubular regions of the treated kidneys on days 1 and 3 post-treatment. Furthermore, cytokine levels in pFUS-treated kidneys following BMSC administration were found to be similar to controls, suggesting modulation of cytokine levels by BMSC. pFUS could potentially improve cell-based therapies as a noninvasive modality to target homing by establishing local chemoattractant gradients and increasing expression of integrins to enhance tropism of cells toward treated tissues.

Disclosure of potential conflicts of interest is found at the end of this article.
Kraftstoffersparnis durch Hochleistungswerkstoffe
Authors: Bobzin Kirsten , Bagcivan Nazlim , Verpoort Clemens , Schramm Leander , Yilmaz Koray , Theiß Sebastian
Published: April 2012

Durch europäische Anordnungen wird der Fortschritt bei der Effizienz von Personenkraftwagen immer wieder forciert. Dies soll maßgeblich durch zwei Maßnahmen erreicht werden. Einerseits kann durch einen konsequenten Leichtbau mit höherfesten Stählen und Leichtmetallen wie Aluminium eine Effizienzsteigerung erzielt werden. Andererseits werden immer öfter Beschichtungen eingesetzt, um Reibungsverluste zu reduzieren. Ein Beispiel, bei dem beide Maßnahmen gleichermaßen eingesetzt werden, ist der Motorenbau. Im Motor werden einerseits Leichtmetalle eingesetzt, um das Fahrzeuggewicht zu reduzieren, und Beschichtungen, um eine maximale Gewichtsreduzierung und einen verbesserten Wirkungsgrad zu erreichen. So werden thermische Spritzverfahren eingesetzt, um die Zylinderlaufbahn eines Leichtmetallmotorblocks vor Verschleiß zu schützen. Um das tribologische System für eine solche Zylinderlaufbahn zu optimieren, können neue mittels Physical Vapour Deposition (PVD) abgeschiedene Dünnschichten auf Kolbenringen die Reibverluste reduzieren und geringeren Verschleiß gewährleisten.
G‐quadruplexes in RNA biology
Authors: Millevoi Stefania , Moine Hervé , Vagner Stéphan
Published: April 2012

G‐quadruplexes are noncanonical structures formed by G‐rich DNA and RNA sequences that fold into a four‐stranded conformation. Experimental studies and computational predictions show that RNA G‐quadruplexes are present in transcripts associated with telomeres, in noncoding sequences of primary transcripts and within mature transcripts. RNA G‐quadruplexes at these specific locations play important roles in key cellular functions, including telomere homeostasis and gene expression. Indeed, RNA G‐quadruplexes appear as important regulators of pre‐mRNA processing (splicing and polyadenylation), RNA turnover, mRNA targeting and translation. The regulatory mechanisms controlled by RNA G‐quadruplexes involve the binding of protein factors that modulate G‐quadruplex conformation and/or serve as a bridge to recruit additional protein regulators. In this review, we summarize the current knowledge on the role of G‐quadruplexes in RNA biology with particular emphasis on the molecular mechanisms underlying their specific function in RNA metabolism occurring in physiological or pathological conditions. WIREs RNA 2012, 3:495–507. doi: 10.1002/wrna.1113

This article is categorized under:

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

RNA Interactions with Proteins and Other Molecules > Protein–RNA Interactions: Functional Implications
Jet dipolarity: top tagging with color flow
Authors: Hook Anson , Jankowiak Martin , Wacker Jay G.
Published: April 2012

Abstract

A new jet observable, dipolarity, is introduced that can distinguish whether a pair of subjets arises from a color singlet source. This observable is incorporated into the HEPTopTagger and is shown to improve discrimination between top jets and QCD jets for moderate to high p

T
.
Genistein, a soya isoflavone, prevents azoxymethane-induced up-regulation of WNT/β-catenin signalling and reduces colon pre-neoplasia in rats
Authors: Zhang Yukun , Li Qian , Zhou Dan , Chen Hong
Published: April 2012

The present study aimed to explore the role(s) of the soya isoflavone genistein (GEN) in preventing the development of colon pre-neoplasia, using Wingless/int (WNT)/β-catenin as a molecular marker of colon abnormality. Specifically, the effects on the WNT/β-catenin signalling pathway from GEN were examined by using an azoxymethane (AOM)-induced rat colon cancer model. Male Sprague–Dawley rats were fed a control (CTL), a soya protein isolate (SPI) or a GEN diet from gestation to 13 weeks of age. The first sampling was conducted at 7 weeks of age for pre-AOM analysis. The remaining rats were injected with AOM at 7 weeks of age. The descending colon was collected 6 weeks later for the evaluation of aberrant crypt foci (ACF), gene expression and nuclear protein accumulation. AOM injection induced aberrant nuclear accumulation of β-catenin in the CTL group but not in the SPI or GEN group. Moreover, the WNT target genesCyclin D1andc-Mycwere repressed by SPI and GEN. Meanwhile, SPI and GEN suppressed the expression of WNT signalling genes includingWnt5a,Sfrp1,Sfrp2andSfrp5to the similar level to that of the pre-AOM period. Rats fed SPI and GEN had a decreased number of total aberrant crypts. GEN feeding also resulted in a reduced number of ACF withN = 3 per foci. The reduction of WNT/β-catenin signalling was correlated with the decrease in total aberrant crypts. By testing WNT/β-catenin signalling as a biomarker of colon carcinogenic potential, we showed the novel role of GEN as a suppressor of carcinogen-induced WNT/β-catenin signalling in preventing the development of early colon neoplasia.
On a new species ofNuchalosyllis(Polychaeta: Syllidae), a rare syllid genus only known from Brazilian waters
Authors: Fukuda Marcelo Veronesi , de Matos Nogueira João Miguel
Published: April 2012

NuchalosyllisRullier & Amoureux, 1979 is an extremely rare syllid genus, only known from the holotype of its type species,N. lamellicornisRullier & Amoureux, 1979. The genus is characterized by the dorso-ventrally flattened body and the unique comb-like nuchal epaulettes. We herein describe the second specimen of this genus ever found, which is also a new species,Nuchalosyllis maiteaesp. nov.; it differs fromN. lamellicornisin having different morphology of nuchal epaulettes, spinose papillae on cirrophores of dorsal cirri throughout and sub-bidentate posterior body falcigers.
Recreational fish feeding inside Brazilian MPAs: impacts on reef fish community structure
Authors: Feitosa Caroline Vieira , Chaves Laís de Carvalho Teixeira , Ferreira Beatrice Padovani , de Araújo Maria Elisabeth
Published: April 2012

Although the practice of recreational feeding of fish by tourists is widespread within marine protected areas (MPAs), the ecological consequences of this activity have received little attention. This research aimed to investigate the influence of artificial feeding on reef fish communities of two Brazilian MPAs. Visual censuses were performed in areas not visited by tourists, in order to characterize the natural community structure of each reef system. In the Maracajaú reefs, the effect of artificial feeding was assessed below a moored floating dock found in the area. Stationary visual censuses were carried out before, during and after the fish feeding activity. In the Maragogi reefs, areas with presence and absence of tourism visitation were established. Transect methodology was employed in each of these areas. On both MPAs, fish feeding was a formal activity and occurred on a daily basis during the course of this study. Within the MPAs, 88 species belonging to 40 families were recorded. In Maracajaú, fish, shrimps and squids were provided by the tourists on the floating dock, which favoured mobile invertebrate feeders, whereas in Maragogi, animal ration and human food were used, causing aggregations of omnivores. Differences were observed in terms of abundance between before and after feeding in Maracajaú and between the control and impacted areas of Maragogi. The data are consistent with fish feeding leading to attraction of determined species, causing an increase in their abundance, also indicating that both the type of food and the extension of activity area are important factors determining the effects on fish communities.
Distribution patterns of deep-sea fish and benthic invertebrates from trawlable grounds of the Hatton Bank, north-east Atlantic: effects of deep-sea bottom trawling
Authors: Durán Muñoz P. , Sayago-Gil M. , Patrocinio T. , González-Porto M. , Murillo F. J. , Sacau M. , González E. , Fernández G. , Gago A.
Published: April 2012

Distributions of deep-sea fish, benthic invertebrates and the effects of deep-sea bottom trawling were studied based on data collected in 2005 from a joint collaboration survey undertaken between the Spanish Institute of Oceanography and a deep-sea trawler on the Hatton Bank (north-east Atlantic). A total of 163 valid bottom trawl hauls (600–1600 m) were analysed. The main trawlable grounds were located on the sedimentary seabed of the western flank of the bank (Hatton Drift). Grenadiers and smoothheads were predominant in the trawl catches (67% and 11.8% by weight respectively). Both species were abundant along the western flank. Deep-water sharks accounted for 7.4% of weight, and were abundant along the south-eastern slopes. Chimerids, lotids, morids and other deep-sea species were also taken as by-catch. Grenadiers and deep-water sharks dominated the discards. By-catches of cold-water corals were generally associated with the rocky outcrop and were more abundant at the top of the bank. Abundant by-catches of large sponges, characteristic of sponge-dominated biotopes, were taken from the eastern flank.
Littoral Tanaidacea (Crustacea: Peracarida) from Macaronesia: allopatry and provenance in recent habitats
Authors: Bamber Roger N.
Published: April 2012

The Macaronesian Islands in the mid-Atlantic pose a number of questions relating to their colonization by littoral tanaidaceans, as these taxa have no obligate dispersive phase. Recent surveys of the four main archipelagos discovered twelve species of tanaidacean, four of which are new to science, in seven genera (one new to science). In addition, some taxa described by Vanhöffen at the beginning of the last century were rediscovered. All the taxa are described, and their zoogeography, likely origin, and possible means of colonization are discussed.
William Forsythe, Eidos:Telos, and Intertextual Criticism
Authors: Nugent Ann
Published: April 2012

At my first performance of Eidos:Telos, in Frankfurt in 1998, I discover a work of penetrating power that is both ordered and disordered. It is febrile at one moment and cool at the next. It is abstract but threaded through with symbolism, and its three acts exude darkness and mystery.

There are no obvious divisions into time or place, and the weave of obscure and fragmented allusions means that dramas build and drop away. The dancing bodies create a mass of curves, lines, and angles with astonishing fluency but in few centrally organized patterns. I try to make sense of the diversity of abstract dance that seems rooted in evasive purpose, and symbolism that lends itself to poetics rather more often than to literal meaning. I search for metaphors that will bind images together, but the imagery is delivered faster than the speed of thought. The movement is rooted in ballet, and fleetingly I sense Apollo lingering; warm to a fragment of Giselle and feel a frisson of excitement when a man sinks to the ground and folds over his body, because it reminds me of Nijinsky's L'Aprés midi d'un faune. But though these connections continue to burn in my mind, they are incidentals and personal to what I see, and quickly succeeded by others.

But I leave Eidos:Telos feeling somehow different, for my body is pumping with energy and ideas, and colorful dynamics are colliding in my head. It has taken me on a journey of the philosophical, kinaesthetic, and sensual, and I need to experience more.
Bodies on the Line: Contact Improvisation and Techniques of Nonviolent Protest
Authors: Goldman Danielle
Published: April 2012

On the morning of May 4, 1961, a brave and motley group of travelers—seven black males, three white males, and three white females, varying in age and professional standing but all trained in nonviolence—embarked on what they called the “Freedom Ride.” Designed by the Congress of Racial Equality (CORE), the bus ride was meant to commemorate and further the organization's 1947 Journey of Reconciliation, a non-violent test of desegregation on interstate buses that quickly disintegrated in the face of staunch resistance. This time, riders would test the 1960 Supreme Court decision Boynton v. Virginia, which prohibited segregation in the waiting rooms and restaurants of bus terminals (Branch 1989, 390). Departing from Washington, D.C., the Freedom Ride aimed to arrive in New Orleans on May 17, the seventh anniversary of Brown v. Board of Education. Explaining that they were merely exercising rights granted by the Supreme Court but that they knew the dangers, CORE director James Farmer said, “We were prepared for the possibility of death” (Cozzens 1997). Riding the momentum of the student sit-ins, the civil rights movement had become for many a matter of “putting your body on the line” (Branch 1989, 392).
Dance in Bronze Age Greece
Authors: German Senta
Published: April 2012

The identification of images of dance from antiquity is very difficult given the limitations of ancient forms of representation, the remoteness of the action itself, and the obscurity of its cultural contexts. These problems are magnified when one considers images of dance from preliterate cultures or those in which written language offers little insight. The following is an investigation into the representation of dance dating to the latter half of the Aegean Bronze Age, during the second millennium BC, as part of the visual culture of the Minoans and Mycenaeans from the island of Crete and the mainland of Greece respectively.
Teaching Styles in Contact Improvisation: An Explicit Discourse with Implicit Meaning
Authors: Engelsrud Gunn
Published: April 2012

Since contact improvisation was “invented” in North America in the 1970s, it has gained widespread acceptance; teachers have been travelling extensively to conduct seminars and workshops. The dance form has been documented and researched from several viewpoints, but, as I see it, there is general agreement among practitioners and scholars—including United Kingdom-based Helen Thomas (2003), Norway-based Hilde Rustad (2006) and Eli Torvik (2005), and Cynthia Novack (1990), who worked in the United States—that contact improvisation is a form of nonhierarchical relations that entails an appeal to accept mutual responsibility for each other and that also implies a specific lifestyle. In her book Sharing the Dance: Contact Improvisation and American Culture, Novack, as an anthropologist, perceives contact improvisation as embodied culture where the movements are central constitutional parts. Her position is that through the study of contact improvisation, “the history of the dancing serves as a vehicle for investigating powerful interrelationships of body, movement, dance and society” (8).
“Splendid Dancing”: Filipino “Exceptionalism” in Taxi Dancehalls
Authors: Burns Lucy Mae San Pablo
Published: April 2012

In the 1920s and early 1930s, Filipino men patronized the popular American social institution of the taxi dancehalls, comprising nearly one quarter of the taxi dancehall patrons in major cities such as Detroit and Los Angeles (see Cressey 1932). Taxi dancehalls were at the height of their popularity during this period, often serving as a key site of sociality amongst and between immigrants. Women were employed as dancers for hire, and men, predominantly immigrants, were their principal patrons. Filipinos, workers and students alike, came dressed in McIntosh suits, eager to spend their hard-earned wages on taxi dancers. Here, Filipino men made rare social contact with women—taxi dancers who were largely white, occasionally Mexican, and very rarely Filipina (see Meckel 1995 for a detailed study of taxi dancers). Filipinos would purchase their dance tickets, choose their favorite girl within a group of taxi dancers, and move to the music of a live band. For ten cents per dance number, slow or fast, Filipino men could choose to dance with the same dancer until their tickets ran out or opt for the pleasures of another. Like a taxi ride, each dance came with a ticketed price and the expectation of a tip, either in the form of a drink, a sandwich, or perhaps even a marriage proposal.
Dance Studies in the International Academy: Genealogy of a Disciplinary Formation
Authors: Giersdorf Jens Richard
Published: April 2012

For the past thirteen years, I have been traveling to the United States from my home country of Germany, first as a graduate student in California and later as a professor living in New York. Every time I pass through immigration, I am asked a series of questions regarding my final destination and my occupation. The latter always leads to some confusion, because when I am asked what I do, my accent seems to turn “dance history” into “dentistry.” Forced by phonetics to use the term “dance studies,” when confronted by the blank face of the customs officer, I inevitably embark on an explanation of what “dance studies” might be. Just in the moment when I finally see some comprehension of my profession lighting up the officer's face, the question is asked: “And we pay you to do this?”

I constantly find myself in the position of having to explain my work. Usually I avoid a long-winded, defensive justification by comparing dance studies to one of its neighboring disciplines: “It is like art history, just writing about dance instead of paintings.” That usually does the trick, but it leaves a foul taste in my mouth. I know that dance studies isn't like art history and I certainly don't want it to be.
From Shusterman's Somaesthetics to a Radical Epistemology of Somatics
Authors: Ginot Isabelle
Published: April 2012

From the precepts of civility and physical deportment in the early modern era to modern gestural routines found in physical therapy and gymnastics, cultural historians of the body have studied the physical practices of hygiene, sports, and medicine. The history of dance is marked by these dance-related practices, which are peripheral to dance itself. One set of contemporary peripheral practices sought out by dancers themselves has been called “somatics,” a term Thomas Hanna proposed in the 1970s (1995). Somatics has since made its way into the dance world, where by now it has achieved widespread recognition as a form of bodily knowledge. This article is concerned with the epistemological status of somatics and, therefore, with the discursive production characteristic of its methods and practices.

The first value that we usually attribute to these practices is prophylactic: they serve to prevent professional accidents or provide functional rehabilitation following injuries. Although increasingly integrated into dancer training and dance pedagogy, somatics first found its way into dance as a means to limit accidents. Somatics is also often a resource for the improvement of virtuosity in dance. But it has nevertheless transformed pedagogy into a more “active” and exploratory experience for the student, in which physical sensations are more important than the mirroring and reproduction of forms (Fortin 1996, 2005; Fortin, Long, and Lord 2002). We often see it presented as a “counter power,” an antidote to dominant dance practices. This point of view is poorly documented—possibly because it would not hold up against a strong argument—but it is common knowledge that somatics stands opposed to virtuosity and the “perfect” body image, as seen, for example, in the role these techniques played in the early part of Trisha Brown's choreographic career.
The history of the International Centre for Diffraction Data
Authors: Messick Julian
Published: April 2012

The International Centre for Diffraction Data has a colorful history, starting as a small task group of involved and interested scientists and progressing through a number of evolutionary steps that were required to deliver scientific products and services globally. The results of these efforts can be found in numerous scientific publications that focus on basic physics, method development, and analyses of the material identification of solid-state materials. This article examines the evolution of the organization through its members and employees.
An effective procedure to design the layout of standard and enhanced mode-S multilateration systems for airport surveillance
Authors: Mantilla-Gaviria Ivan A. , Leonardi Mauro , Galati Gaspare , Balbastre-Tejedor Juan V. , de los Reyes Davó Elías
Published: April 2012

In this paper, an effective procedure to emplace standard and enhanced mode-S multilateration stations for airport surveillance is studied and developed. This procedure is based on meta-heuristic optimization techniques, such as genetic algorithm (GA), and is intended to obtain useful parameters for an optimal system configuration that provides acceptable performance levels. Furthermore, the procedure developed here is able to evaluate and improve previous system designs, as well as possible system enhancements. Additionally, the design strategies to be used along with the procedure proposed here are fully described. Parameters such as the number of stations, the system geometry, the kind of measurements to be used, and the system accuracy are obtained taking into account the basic requirements such as the Line of Sight, the probability of detection, and the accuracy levels.
Improving the stability of a simple formulation of the shallow water equations for 2‐D flood modeling
Authors: de Almeida Gustavo A. M. , Bates Paul , Freer Jim E. , Souvignet Maxime
Published: April 2012

The ability of two‐dimensional hydrodynamic models to accurately and efficiently predict the propagation of floods over large urban areas is of paramount importance for flood risk assessment and management. Paradoxically, it is in these highly relevant urban domains where flood modeling faces some of the most challenging obstacles. This is because of the very high‐resolution topography that is typically required to capture key hydraulic features, which significantly increases the computational time of the model. One particularly interesting solution to this difficulty was recently proposed in the form of a numerical scheme for the solution of a simplified version of the shallow water equations, which yields a system of two explicit equations that captures the most relevant hydraulic processes at very high computational efficiency. However, some stability problems were reported, especially when this formulation is applied to low friction areas. This is of particular importance in urban areas, where smooth surfaces are usually abundant. This paper proposes and tests two modifications of this previous numerical scheme that considerably improves the numerical stability of the model. Model improvements were assessed against a structured set of idealized test cases and finally in the simulation of flood propagation over complex topography in a highly urbanized area in London, United Kingdom. The enhanced stability achieved by the new formulation comes at no significant additional computational cost and, in fact, the model performance can benefit from the longer time steps that are allowed by the new scheme.
The cost of research in developing countries
Authors: van Helden Paul
Published: April 2012

Scientists in developing countries face lower absolute levels of funding and often have to pay scandalously higher prices for consumables and equipment.
ARGon3: “3D appearance robot-based gonioreflectometer” at PTB
Authors: Höpe A. , Atamas T. , Hünerhoff D. , Teichert S. , Hauer K.-O.
Published: April 2012

At the Physikalisch-Technische Bundesanstalt, the National Metrology Institute of Germany, a new facility for measuring visual appearance-related quantities has been built up. The acronym ARGon3 stands for “3D appearance robot-based gonioreflectometer”. Compared to standard gonioreflectometers, there are two main new features within this setup. First, a photometric luminance camera with a spatial resolution of 28 μm on the device under test (DUT) enables spatially high-resolved measurements of luminance and color coordinates. Second, a line-scan CCD-camera mounted to a spectrometer provides measurements of the radiance factor, respectively the bidirectional reflectance distribution function, in full V(λ)-range (360 nm–830 nm) with arbitrary angles of irradiation and detection relative to the surface normal, on a time scale of about 2 min. First goniometric measurements of diffuse reflection within 3D-space above the DUT with subsequent colorimetric representation of the obtained data of special effect pigments based on the interference effect are presented.
Two-dimensional laser induced fluorescence spectroscopy of van der Waals complexes: Fluorobenzene-Arn (n = 1,2)
Authors: Gascooke Jason R. , Alexander Ula N. , Lawrance Warren D.
Published: April 2012

The technique of two-dimensional laser induced fluorescence (2D-LIF) spectroscopy has been used to observe the van der Waals complexes fluorobenzene-Ar and fluorobenzene-Ar2 in the region of their S1-S0 electronic origins. The 2D-LIF spectral images reveal a number of features assigned to the van der Waals vibrations in S0 and S1. An advantage of 2D-LIF spectroscopy is that the LIF spectrum associated with a particular species may be extracted from an image. This is illustrated for fluorobenzene-Ar. The S1 van der Waals modes observed in this spectrum are consistent with previous observations using mass resolved resonance enhanced multiphoton ionisation techniques. For S0, the two bending modes previously observed using a Raman technique were observed along with three new levels. These agree exceptionally well with ab initio calculations. The Fermi resonance between the stretch and bend overtone has been analysed in both the S0 and S1 states, revealing that the coupling is stronger in S0 than in S1. For fluorobenzene-Ar2 the 2D-LIF spectral image reveals the S0 symmetric stretch van der Waals vibration to be 35.0 cm−1, closely matching the value predicted based on the fluorobenzene-Ar van der Waals stretch frequency. Rotational band contour analysis has been performed on the fluorobenzene-Ar $\overline {0_0^0 }$000¯ transition to yield a set of S1 rotational constants A′ = 0.05871 ± 0.00014 cm−1, B′ = 0.03803 ± 0.00010 cm−1, and C′ = 0.03103 ± 0.00003 cm−1. The rotational constants imply that in the S1 00 level the Ar is on average 3.488 Å from the fluorobenzene centre of mass and displaced from it towards the centre of the ring at an angle of ∼6° to the normal. The rotational contour for fluorobenzene-Ar2 was predicted using rotational constants calculated on the basis of the fluorobenzene-Ar geometry and compared with the experimental contour. The comparison is poor which, while due in part to expected saturation effects, suggests the presence of another band lying beneath the contour.
Channelling optics for high quality imaging of sensory hair
Authors: Skupsch C. , Klotz T. , Chaves H. , Brücker C.
Published: April 2012

A long distance microscope (LDM) is extended by a lens and aperture array. This newly formed channelling LDM is superior in high quality, high-speed imaging of large field of views (FOV). It allows imaging the same FOV like a conventional LDM, but at improved magnification. The optical design is evaluated by calculations with the ray tracing code ZEMAX. High-speed imaging of a 2 × 2 mm2 FOV is realized at 3.000 frames per second and 1 μm per pixel image resolution. In combination with flow sensitive hair the optics forms a wall shear stress sensor. The optics images the direct vicinity of twenty-one flow sensitive hair distributed in a quadratic array. The hair consists of identical micro-pillars that are 20 μm in diameter, 390 μm in length and made from polydimethylsiloxane (PDMS). Sensor validation is conducted in the transition region of a wall jet in air. The wall shear stress is calculated from optically measured micro-pillar tip deflections. 2D wall shear stress distributions are obtained with currently highest spatiotemporal resolution. The footprint of coherent vortical structures far away from the wall is recovered in the Fourier spectrum of wall shear stress fluctuations. High energetic patterns of 2D wall shear stress distributions are identified by proper orthogonal decomposition (POD).
Field-structured magnetic platelets as a route to improved thermal interface materials
Authors: Solis Kyle J. , Martin James E.
Published: April 2012

The development of high-performance thermal interface materials (TIMs) is crucial to enabling future generations of microelectronics because the TIM is usually the limiting thermal resistance in the heat removal path. Typical TIMs achieve modest thermal conductivities by including large volume fractions of randomly-dispersed, highly-conductive, spherical particles in a polymer resin. This paper explores field-structured magnetic platelet composites as a new approach to more effective TIMs. The motivation for this approach is rooted in shape functional theory, which shows that when the particle material has a significantly higher thermal conductivity than that of the polymer, the particle shape and orientation are the factors that limit conductivity enhancement. Oriented platelets are highly effective for heat transfer and if these are magnetic, then magnetic fields can be used to both orient and agglomerate these into structures that efficiently direct heat flow. In this paper we show that such field-structured composites have a thermal conductivity anisotropy of ∼3, and at the highest particle loading of 16 vol.% we have achieved a 23-fold conductivity enhancement, which is 3-times larger than that achieved in unstructured platelet composites and 8-times greater than unstructured spherical particle composites.
Novel on-demand droplet generation for selective fluid sample extraction
Authors: Lin Robert , Fisher Jeffery S. , Simon Melinda G. , Lee Abraham P.
Published: April 2012

A novel microfluidic device enabling selective generation of droplets and encapsulation of targets is presented. Unlike conventional methods, the presented mechanism generates droplets with unique selectivity by utilizing a K-junction design. The K-junction is a modified version of the classic T-junction with an added leg that serves as the exit channel for waste. The dispersed phase fluid enters from one diagonal of the K and exits the other diagonal while the continuous phase travels in the straight leg of the K. The intersection forms an interface that allows the dispersed phase to be controllably injected through actuation of an elastomer membrane located above the inlet channel near the interface. We have characterized two critical components in controlling the droplet size—membrane actuation pressure and timing as well as identified the region of fluid in which the droplet will be formed. This scheme will have applications in fluid sampling processes and selective encapsulation of materials. Selective encapsulation of a single cell from the dispersed phase fluid is demonstrated as an example of functionality of this design.
Random telegraph signal noise in gate current of unstressed and reverse-bias-stressed AlGaN/GaN high electron mobility transistors
Authors: Marko P. , Alexewicz A. , Hilt O. , Meneghesso G. , Zanoni E. , Würfl J. , Strasser G. , Pogany D.
Published: April 2012

Random telegraph signal (RTS) fluctuations with relative amplitude up to 50% are observed in forward and reverse gate current of unstressed and reverse-bias-stressed AlGaN/GaN high electron mobility transistors. Measurements of RTS amplitude and mean pulse widths as a function of forward gate bias indicate that the RTS is due to modulation of current along an intrinsic or stress-induced percolation path across the AlGaN-barrier by electron capture and emission on a trap within the barrier. Processes of electron capture from GaN to trap and subsequent tunneling to metal gate or electron exchange between GaN channel and the trap are considered.
Characterizations of photoconductivity of graphene oxide thin films
Authors: Chang-Jian Shiang-Kuo , Ho Jeng-Rong , Cheng J.-W. John , Hsieh Ya-Ping
Published: April 2012

Characterizations of photoresponse of a graphene oxide (GO) thin film to a near infrared laser light were studied. Results showed the photocurrent in the GO thin film was cathodic, always flowing in an opposite direction to the initial current generated by the preset bias voltage that shows a fundamental discrepancy from the photocurrent in the reduced graphene oxide thin film. Light illumination on the GO thin film thus results in more free electrons that offset the initial current. By examining GO thin films reduced at different temperatures, the critical temperature for reversing the photocurrent from cathodic to anodic was found around 187°C. The dynamic photoresponse for the GO thin film was further characterized through the response time constants within the laser on and off durations, denoted as τon and τoff, respectively. τon for the GO thin film was comparable to the other carbon-based thin films such as carbon nanotubes and graphenes. τoff was, however, much larger than that of the other's. This discrepancy was attributable to the retardation of exciton recombination rate thanks to the existing oxygen functional groups and defects in the GO thin films.
Grid cells in rat entorhinal cortex encode physical space with independent firing fields and phase precession at the single-trial level
Authors: Reifenstein Eric T. , Kempter Richard , Schreiber Susanne , Stemmler Martin B. , Herz Andreas V. M.
Published: April 2012

When a rat moves, grid cells in its entorhinal cortex become active in multiple regions of the external world that form a hexagonal lattice. As the animal traverses one such “firing field,” spikes tend to occur at successively earlier theta phases of the local field potential. This phenomenon is called phase precession. Here, we show that spike phases provide 80% more spatial information than spike counts and that they improve position estimates from single neurons down to a few centimeters. To understand what limits the resolution and how variable spike phases are across different field traversals, we analyze spike trains run by run. We find that the multiple firing fields of a grid cell operate as independent elements for encoding physical space. In addition, phase precession is significantly stronger than the pooled-run data suggest. Despite the inherent stochasticity of grid-cell firing, phase precession is therefore a robust phenomenon at the single-trial level, making a theta-phase code for spatial navigation feasible.
Target genes of Topoisomerase IIβ regulate neuronal survival and are defined by their chromatin state
Authors: Tiwari Vijay K. , Burger Lukas , Nikoletopoulou Vassiliki , Deogracias Ruben , Thakurela Sudhir , Wirbelauer Christiane , Kaut Johannes , Terranova Remi , Hoerner Leslie , Mielke Christian , Boege Fritz , Murr Rabih , Peters Antoine H. F. M. , Barde Yves-Alain , Schübeler Dirk
Published: April 2012

Topoisomerases are essential for DNA replication in dividing cells, but their genomic targets and function in postmitotic cells remain poorly understood. Here we show that a switch in the expression from Topoisomerases IIα (Top2α) to IIβ (Top2β) occurs during neuronal differentiation in vitro and in vivo. Genome-scale location analysis in stem cell–derived postmitotic neurons reveals Top2β binding to chromosomal sites that are methylated at lysine 4 of histone H3, a feature of regulatory regions. Indeed Top2β-bound sites are preferentially promoters and become targets during the transition from neuronal progenitors to neurons, at a time when cells exit the cell cycle. Absence of Top2β protein or its activity leads to changes in transcription and chromatin accessibility at many target genes. Top2β deficiency does not impair stem cell properties and early steps of neuronal differentiation but causes premature death of postmitotic neurons. This neuronal degeneration is caused by up-regulation of
Ngfr
p75, a gene bound and repressed by Top2β. These findings suggest a chromatin-based targeting of Top2β to regulatory regions in the genome to govern the transcriptional program associated with neuronal differentiation and longevity.
Structural and mechanistic analysis of the membrane-embedded glycosyltransferase WaaA required for lipopolysaccharide synthesis
Authors: Schmidt Helgo , Hansen Guido , Singh Sonia , Hanuszkiewicz Anna , Lindner Buko , Fukase Koichi , Woodard Ronald W. , Holst Otto , Hilgenfeld Rolf , Mamat Uwe , Mesters Jeroen R.
Published: April 2012

WaaA is a key enzyme in the biosynthesis of LPS, a critical component of the outer envelope of Gram-negative bacteria. Embedded in the cytoplasmic face of the inner membrane, WaaA catalyzes the transfer of 3-deoxy-
d
-
manno
-oct-2-ulosonic acid (Kdo) to the lipid A precursor of LPS. Here we present crystal structures of the free and CMP-bound forms of WaaA from
Aquifex aeolicus
, an ancient Gram-negative hyperthermophile. These structures reveal details of the CMP-binding site and implicate a unique sequence motif (GGS/TX
5
GXNXLE) in Kdo binding. In addition, a cluster of highly conserved amino acid residues was identified which represents the potential membrane-attachment and acceptor-substrate binding site of WaaA. A series of site-directed mutagenesis experiments revealed critical roles for glycine 30 and glutamate 31 in Kdo transfer. Our results provide the structural basis of a critical reaction in LPS biosynthesis and allowed the development of a detailed model of the catalytic mechanism of WaaA.
Motor neurons controlling fluid ingestion in
Drosophila
Authors: Manzo Andrea , Silies Marion , Gohl Daryl M. , Scott Kristin
Published: April 2012

Rhythmic motor behaviors such as feeding are driven by neural networks that can be modulated by external stimuli and internal states. In
Drosophila
, ingestion is accomplished by a pump that draws fluid into the esophagus. Here we examine how pumping is regulated and characterize motor neurons innervating the pump. Frequency of pumping is not affected by sucrose concentration or hunger but is altered by fluid viscosity. Inactivating motor neurons disrupts pumping and ingestion, whereas activating them elicits arrhythmic pumping. These motor neurons respond to taste stimuli and show prolonged activity to palatable substances. This work describes an important component of the neural circuit for feeding in
Drosophila
and is a step toward understanding the rhythmic activity producing ingestion.
Shift-driven modulations of spin-echo signals
Authors: Smith Pieter E. S. , Bensky Guy , Álvarez Gonzalo A. , Kurizki Gershon , Frydman Lucio
Published: April 2012

Since the pioneering works of Carr-Purcell and Meiboom-Gill [Carr HY, Purcell EM (1954) Phys Rev 94:630; Meiboom S, Gill D (1985) Rev Sci Instrum 29:688], trains ofπ-pulses have featured amongst the main tools of quantum control. Echo trains find widespread use in nuclear magnetic resonance spectroscopy (NMR) and imaging (MRI), thanks to their ability to free the evolution of a spin-1/2 from several sources of decoherence. Spin echoes have also been researched in dynamic decoupling scenarios, for prolonging the lifetimes of quantum states or coherences. Inspired by this search we introduce a family of spin-echo sequences, which can still detect site-specific interactions like the chemical shift. This is achieved thanks to the presence of weak environmental fluctuations of common occurrence in high-field NMR—such as homonuclear spin-spin couplings or chemical/biochemical exchanges. Both intuitive and rigorous derivations of the resulting “selective dynamical recoupling” sequences are provided. Applications of these novel experiments are given for a variety of NMR scenarios including determinations of shift effects under inhomogeneities overwhelming individual chemical identities, and model-free characterizations of chemically exchanging partners.
Similar temporal and spatial recruitment of native 19S and 20S proteasome subunits to transcriptionally active chromatin
Authors: Geng Fuqiang , Tansey William P.
Published: April 2012

It has recently become clear that components of the proteasome are recruited to sites of gene transcription. Prevailing evidence suggests that the transcriptionally relevant form of the proteasome is a subcomplex of 19S base proteins, which functions as an ATP-dependent chaperone that influences transcriptional processes. Despite this notion, compelling evidence for a transcription-dedicated 19S base complex is lacking, and 20S proteasome subunits have been shown to associate with chromatin in some contexts. To gain insight into the form of the proteasome that is recruited to chromatin, we assembled a panel of highly specific antibodies that recognize native yeast proteasome subunits in chromatin immunoprecipitation assays. Using these reagents, we show that components from the three major subassemblies of the proteasome—19S lid, 19S base, and 20S core—associate with the activated
GAL10
gene in yeast in a virtually indistinguishable manner. We find that proteasome subunits Rpt1, Rpt4, Rpn8, Rpn12, Pre6, and Pre10 are recruited to
GAL10
rapidly upon galactose induction. These subunits associate with the entire transcribed portion of
GAL10
, display near-identical patterns of distribution, and dissociate from chromatin rapidly once transcription is shut down. We also find that proteasome subunits are enriched at telomeres and at genes transcribed by RNA polymerase III. Our data suggest that the transcriptionally relevant form of the proteasome is the canonical 26S complex.
Inducible NOS-induced chloride intracellular channel 4 (CLIC4) nuclear translocation regulates macrophage deactivation
Authors: Malik Mariam , Jividen Kasey , Padmakumar V. C. , Cataisson Christophe , Li Luowei , Lee Jessica , Howard O. M. Zack , Yuspa Stuart H.
Published: April 2012

Nuclear translocation of cytosolic CLIC4 is an essential feature of its proapoptotic and prodifferentiation functions. Here we demonstrate that CLIC4 is induced concurrently with inducible nitric oxide synthase (iNOS) and S-nitrosylated in proinflammatory peritoneal macrophages. Chemical inhibition or genetic ablation of iNOS inhibits S-nitrosylation and nuclear translocation of CLIC4. In macrophages, iNOS-induced nuclear CLIC4 coincides with the pro- to anti-inflammatory transition of the cells because IL-1β and CXCL1 mRNA remain elevated in CLIC4 and iNOS knockout macrophages at late time points, whereas TNFα mRNA is elevated only in the iNOS knockout macrophages. Active IL-1β remains elevated in CLIC4 knockout macrophages and in macrophages in which CLIC4 nuclear translocation is prevented by the NOS inhibitor
l
-NAME. Moreover, overexpression of nuclear-targeted CLIC4 down-regulates IL-1β in stimulated macrophages. In mice, genetically null for CLIC4, the number of phagocytosing macrophages stimulated by LPS is reduced. Thus, iNOS-induced nuclear CLIC4 is an essential part of the macrophage deactivation program.
Peierls distortion mediated reversible phase transition in GeTe under pressure
Authors: Sun Zhimei , Zhou Jian , Mao Ho-Kwang , Ahuja Rajeev
Published: April 2012

With the advent of big synchrotron facilities around the world, pressure is now routinely placed to design a new material or manipulate the properties of materials. In GeTe, an important phase-change material that utilizes the property contrast between the crystalline and amorphous states for data storage, we observed a reversible phase transition of rhombohedral↔rocksalt↔orthorhombic↔monoclinic coupled with a semiconductor↔metal interconversion under pressure on the basis of
ab initio
molecular dynamics simulations. This interesting reversible phase transition under pressure is believed to be mediated by Peierls distortion in GeTe. Our results suggest a unique way to understand the reversible phase transition and hence the resistance switching that is crucial to the applications of phase-change materials in nonvolatile memory. The present finding can also be expanded to other IV-VI semiconductors.
Properties of the human Cdc45/Mcm2-7/GINS helicase complex and its action with DNA polymerase ε in rolling circle DNA synthesis
Authors: Kang Young-Hoon , Galal Wiebke Chemnitz , Farina Andrea , Tappin Inger , Hurwitz Jerard
Published: April 2012

In eukaryotes, although the Mcm2-7 complex is a key component of the replicative DNA helicase, its association with Cdc45 and GINS (the CMG complex) is required for the activation of the DNA helicase. Here, we show that the CMG complex is localized to chromatin in human cells and describe the biochemical properties of the human CMG complex purified from baculovirus-infected Sf9 cells. The isolated complex binds to ssDNA regions in the presence of magnesium and ATP (or a nonhydrolyzable ATP analog), contains maximal DNA helicase in the presence of forked DNA structures, and translocates along the leading strand (3′ to 5′ direction). The complex hydrolyses ATP in the absence of DNA; unwinds duplex regions up to 500 bp; and either replication protein A or
Escherichia coli
single stranded binding protein increases the efficiency of displacement of long duplex regions. Using a 200-nt primed circular DNA substrate, the combined action of human DNA polymerase ε and the human CMG complex leads to the formation of products >10 kb in length. These findings suggest that the coordinated action of these replication complexes supports leading strand synthesis.