bluuebunny/crossref_metadata_2025 huggingface dataset:
Crowding, sex ratio and horn evolution in a South African beetle community
Authors: Pomfret Joanne C , Knell Robert J
Published: November 2007

Sexually selected ornaments and weapons are exceptionally variable, even between closely related species. It has long been recognized that some of this diversity can be explained by differences in mating systems between species, but there remains substantial variation between species with similar mating systems. We investigated the roles of sex ratio (measured as operational sex ratio, OSR) and population density (measured as mean male crowding, a measure indicating the average number of conspecific males that an individual male animal will encounter) in determining horn presence in a community of South African dung beetles. Analysis of data from 14 species using a generalized least-squares model incorporating phylogenetic influences found that both OSR and mean crowding were significant predictors of horn presence, with hornless species tending to show female-biased sex ratios and high levels of crowding. The influence of mean crowding on horn diversity between species probably reflects the difficulty of guarding and monopolizing females when many competitors are present, meaning that males who adopt ‘scramble’ tactics tend to be favoured.
Solution NMR studies of apo‐mSin3A and ‐mSin3B reveal that the PAH1 and PAH2 domains are structurally independent
Authors: He Yuan , Radhakrishnan Ishwar
Published: November 2007

The evolutionarily conserved mammalian Sin3 (mSin3) transcriptional corepressor interacts with a diverse array of transcription factors mainly through two PAH (paired amphipathic helix) domains located near the N terminus. Previous studies suggested the possibility of interdomain interactions involving the PAH domains. Here, we show that the domains are structurally independent and the properties of the individual domains, such as the conformational heterogeneity and the ability of mSin3A PAH2 to homodimerize, are preserved in constructs that span both PAH domains. Our results thus suggest that the N‐terminal segments of the Sin3 proteins are broadly available for interactions with other proteins and that the PAH domains are organized into structurally independent modules. Our data also rule out any heterotypic association between the paralogous mSin3A and mSin3B proteins via interactions involving the mSin3A PAH2 domain.
Physiological Basis for Differences in Resistance to Microdochium nivale (Fr.) Samuels and Hallett in Two Androgenic Genotypes of Festulolium Derived from Tetraploid F1 Hybrids of Festuca pratensis × Lolium multiflorum (Festulolium)
Authors: Pociecha E. , Płażek A. , Janowiak F. , Janeczko A. , Zwierzykowski Z.
Published: November 2007

The aim of this study was to investigate the physiological basis for differences in resistance to pink snow mould (Microdochium nivale) in two androgenic genotypes of Festulolium (Festuca pratensis × Lolium multiflorum) which differed in terms of their resistance to M. nivale. Genotype 716 was more resistant than genotype 729. The study consisted of two experiments. The aim of the first experiment was to estimate the ability of the plants to survive winter conditions. The aim of the second experiment was to find physiological markers of resistance to snow mould. Festulolium plants were infected with M. nivale mycelium after pre‐hardening and hardening. After 2 weeks in the dark at 2°C, there was a sharp increase in the phenolic content in both genotypes. The increase was greater in the more resistant genotype 716 than in genotype 729. Phenolics therefore may play a very important role in overwintering in grasses, similar to carbohydrates. Based on the differences between the two genotypes, potential indicators of resistance to M. nivale in Festulolium include increased soluble carbohydrate content, increased phenolic content, increased hydrogen peroxide accumulation, decreased catalase activity, increased abscisic acid content and reduced heat emission.
Factors influencing Willow Tit Poecile montanus site occupancy: a comparison of abandoned and occupied woods
Authors: LEWIS ALEX J. G. , AMAR ARJUN , CORDI‐PIEC DANIEL , THEWLIS RICHARD M.
Published: November 2007

The British Willow Tit Poecile montanus kleinschmidti underwent a decline of 85% between 1970 and 2003. The cause of this decline is unknown. However, several hypotheses have been put forward to account for it: competition from other tit species, predation by Great Spotted Woodpeckers Dendrocopos major and habitat change. In order to test these, woods that are currently occupied by Willow Tits were paired with woods (within 50 km) that had been abandoned by Willow Tits five or more years previously. Point counts for other tit species (potential competitors) and woodpecker species (potential predators) were carried out at ten evenly spaced points throughout each wood. Habitat variables were collected within a 50‐m radius of where a Willow Tit was located (in the occupied woods) or where maps showed a Willow Tit had been located (for abandoned woods). No evidence was found for differences in numbers of potential competitor or potential predator species in abandoned and occupied woods. Soil water content was found to be higher at occupied sites. No other habitat features differed between the two categories of site. The drying up of British woods could therefore be implicated in the Willow Tit decline and this warrants further investigation.
Développement du fruit de Prunus serotina (Rosaceae)
Authors: Labrecque Michel , Barabé Denis
Published: November 2007

The authors follow, from full bloom to ripening, the development of the fruit of Prunus serotina, which lasts 13 weeks. Microscopic observations of serial sections, taken from different stages of development, reveal three distinct phases of growth. After fertilization an increase in the number and size of the cells of the mesocarp contributes to rapid growth of the dimensions of the fruit. Toward the end of this first phase, the endocarp starts to differentiate and thickens considerably. Two distinct layers become apparent: an interior one composed of horizontal elongated fibers and another, exterior, composed of isodiametric sclereids. The second stage is characterized by a decrease in the rate of growth of the fruit. The most important anatomical changes are observed in the seed, in which the embryo grows to invade most of the space delimited by the seed coat. At the end of their maturation, the cherries show another growth period, resulting in yet another increase in the size of the cells of the mesocarp. The vascular system comprises one dorsal, two lateral, two ventral, and two ovular bundles. The development of the fruit of Prunus serotina is compared with that of other species of Prunus.
A WEIGHTED INVERSE MINIMUM CUT PROBLEM UNDER THE BOTTLENECK TYPE HAMMING DISTANCE
Authors: LIU LONGCHENG , YAO ENYU
Published: November 2007

An inverse optimization problem is defined as follows. Let S denote the set of feasible solutions of an optimization problem P, let c be a specified cost (capacity) vector, and x0 ∈ S. We want to perturb the cost (capacity) vector c to d so that x0 is an optimal solution of P with respect to the cost (capacity) vector d, and to minimize some objective function. In this paper, we consider the weighted inverse minimum cut problem under the bottleneck type Hamming distance. For the general case, we present a combinatorial algorithm that runs in strongly polynomial time.
A NOTE ON MOND-WEIR TYPE SECOND-ORDER SYMMETRIC DUALITY
Authors: GULATI T. R. , GUPTA S. K.
Published: November 2007

In this paper, we establish a strong duality theorem for a pair of Mond–Weir type second-order nondifferentiable symmetric dual problems. This removes certain inconsistencies in some of the earlier results.
Wireless Sensor Networks: Realizing the Dream
Authors: Gaura E. , Newman R. M.
Published: November 2007

This paper presents a thought experiment as to the feasibility of using large scale wireless sensor networks as a vehicle for high level scientific investigation. The discussion is framed by a demanding scenario, that of planetary exploration, and the assessment of feasibility is driven by the available micromachining technologies and recent advances in the areas of ad-hoc networking, communications and intelligent sensing. Following the development of the mission, the next question addressed is that of how MEMS and VLSI technologies may be integrated to provide a self-contained space probe, 40mm in length. A sensor payload is proposed, which includes seismic, chemical, temperature and visual exploration. Possible means are discussed for developing integrated sensors to address these sensing requirements. The energy and communications systems are also discussed, based on the needs of a mission profile, which provides no special 'base statio n' nodes on the surface, requiring each sensor package to be capable of communication with an orbiting satellite. It is concluded that the sensor node hardware would appear to be feasible, with current levels of MEMS and VLSI technologies. It is hoped that the study will enthuse and encourage researchers from a variety of domains, including micro-engineering and the computer sciences to explore in depth the potential of the wireless sensor networks and give them some high level awareness as to the constraints the design of such systems impose.
Characterization of a-SiC:H as Masking Material in MEMS Applications
Authors: Reyes-Betanzo C. , Zuñiga-Islas C. , Pérez-Trejo A. , Rosas-Guevara G. , Itzmoyotl-Toxqui A. , Calleja-Arriaga W. , Torres-Jácome A.
Published: November 2007

In this work a characterization of silicon carbide films (a- SiC:H) to be used as masking material in wet etching of silicon and glass for MEMS applications is presented. Silicon carbide was deposited by PECVD from silane and methane mixture diluted with hydrogen, at low RF frequency. Film chemical bondings were characterized by IR spectrophotometry and UV/visible transmitance, the surface quality of films was estimated by AFM. A correlation among the Si-C bonding concentration, grain density on film surface, and the films etching resistant was observed. In order to pattern the silicon carbide, samples were dry etched in a RIE/ICP system with CF4 gas, and etch rates as high as 1000 Aå/min were achieved. Silicon carbide films with low rate of silane in the mixture proved to be more resistant to wet solutions of KOH and HF:Cl for etching of silicon and glass, respectively.
Fabrication of an Electro-Optical Temperature Sensor Based on Silicon Oxynitride Films Deposited by PECVD
Authors: Martins G. S. , Mina A. M. , Alayo M. I.
Published: November 2007

We present the fabrication and characterization of an electro-optical temperature sensor based on silicon oxynitride dielectric films deposited by Plasma Enhanced Chemical Vapor Deposition at low temperatures (~300oC). The temperature sensor is basically a Mach-Zehnder interferometer such that a temperature difference between its arms produces a phase difference between the electromagnetic waves traveling through each arm thus originating a variation in the output optical power. In order to analyze the feasibility of this sensor, a temperature difference is imposed by applying a heating element in one of the arms. The results show that it is possible to control the optical device output through the adequate control of the heating element. Furthermore, the influence of heat propagation, multimode noise and methods to obtain monomode optical waveguides and self-sustained Mach- Zehnder structures are discussed in this work.
Sigma-Delta Analog to Digital Converter for use in Lab-on-a-Chip Devices for Biochemical Clinical Analyses
Authors: Minas G. , Rocha J. G.
Published: November 2007

This paper describes a sigma-delta analog to digital converter, which was designed for use in lab-on-a-chip devices, especially in low- cost measurement of biochemical substances in biological fluids by spectrophotometric analysis. The optical sensors were integrated in the same fabrication CMOS process with the analog to digital converters, which are based on sigma-delta modulators. Signals proportional to the intensity of the transmitted light through the biological fluids, which are proportional to the biochemical substance concentration, are available at the output in the form of bit streams allowing simple computer interfacing. Although the sigma-delta converters designed for this project have a very simple architecture, they have other advantages relatively to other interfacing devices used with the same purpose, namely, the noise that is integrated with the signal and then digitally filtered, which means that, except for its small quantity in the signal band, it is eliminated by the device.
Channel Length Reduction Influence on Harmonic Distortion of Graded-Channel Gate-All-Around Devices
Authors: Doria R. T. , Pavanello M. A. , Cerdeira A. , Raskin J. P. , Flandre D.
Published: November 2007

This work compares the linearity of conventional and Graded- Channel (GC) Gate-All-Around (GAA) devices for analog operation as in an amplifier when the channel length is scaled. The study has been performed through two-dimensional process and device simulations. Total harmonic distortion (THD) and third order harmonic distortion (HD3) have been evaluated. When taking into account similar bias the performance of GC GAA transistors remains better than the uniformly doped GAA for any channel length. Although scaling the devices tends to degrade the harmonic distortion, significant results were obtained for the GC configuration measured as an improvement of more than 15 dB in total harmonic distortion-to-gain ratio operating in the same region with channel length of 1μm and with lightly doped region length of 0.3 μm.
RF CMOS Device Modelling for on Chip EMC Evaluation
Authors: Dias Rangel Ryan M. , da Costa José C.
Published: November 2007

In this work a SOC (System On Chip) design methodology, considering electromagnetic compatibility (EMC) is proposed. High frequency CMOS device models have been revised and adapted to the conditions required by a particular SoC chip. RF simulations were carried out in analog and digital SoĆs CMOS cells, using these models, including electromagnetic interference.
Influence of the Tunneling Gate Current on C-V Curves
Authors: Rodrigues Michele , Sonnenberg Victor , Martino João A.
Published: November 2007

This paper presents a study of the tunneling gate current influence on the Capacitance vs. Voltage curve in deep submicrometer CMOS technology. Two-dimensional numerical simulations are performed considering thin gate oxide and N+ polysilicon as a gate material. The influence of the tunneling gate current on the polysilicon depletion region is also analysed. It is observed that the tunneling current masks the polysilicon depletion effect due to the large increase of the substrate silicon depletion region.
Influence of Nucleation Parameters in Ge NCs Formation by LPCVD
Authors: Marins E S. , Mestanza S. N. , Teixeira R. C. , Doi I.
Published: November 2007

In this work, we study the nucleation phase that precedes the growth of Ge nanostructures (ns) on SiO2 matrix by LPCVD (Low Pressure Chemical Vapor Deposition). The influence of the nucleation parameters on size and spatial distribution of Ge ns is analyzed. Results of atomic force microscopy (AFM) show that a high ns density of 3.6x1010 cm-2, with a mean size of 11 nm, can be obtained with the set of the following parameters: 600o C/5 Torr/10 sccm SiH4. Results of high resolution transmission electron microscopy (HRTEM) show that obtained Ge ns are nanocrystals (NCs).
Effects of Non-Uniform Size Distrubution on the Spectral Optical Gain Properties of InGaAs/InGaAsP Quantum Dots
Authors: Mialichi J. R. , Frateschi N. C.
Published: November 2007

We present the theoretical study of optical gain in quantum dots based on the InGaAs/InGaAsP system. A complete computational tool was developed to allow the analysis of the effects of the size distribution of the dots. Spectral gain curves are generated for InGaAs/InGaAsP dots where high optical gain and high independence of spectral characteristics are obtained for a uniform distribution of dots. With typical non-uniform distribution, we show a reduction in gain by a factor of 3. Also, we predict the onset of new transition peaks and a red shift in the most probable operating lasing wavelength.
Magnetic Nanocomposite Thin Films Prepared by Sol-Gel Process
Authors: Seara Luciana M. , Ardisson José D. , Mohallem Nelcy D.
Published: November 2007

Nanostructure oxide thin films have potential technological use due to their unique properties, diverse from those of similar polycrystalline materials. The use of an inorganic matrix as a nanocrystalline particle host allows uniform particle size, and homogeneous distribution and dispersion. Nickel and cobalt ferrite and ferrite composite thin films using silica matrix were prepared by sol-gel process using tetraethylorthosilicate (TEOS) as a precursor of silica, and metallic nitrates as precursors of ferrite. The films were prepared and deposited on various substrates using the dip- coating process. The films obtained were adherent, transparent, homogeneous and free of microcracks and presented crystalline NiFe2O4, CoFe2O4, NiFe2O4/SiO2 and NiFe2O4/SiO2 phases and other phases in minor proportion.
Formation of Anodically Self-Assembled Oxidized Aluminum for Photonic Crystal Fabrication
Authors: Raimundo Daniel S. , Fernandez Francisco J. , Salcedo Walter J.
Published: November 2007

The aim of the present work was to contribute to the nanostructured selfassembled systems fabrication to photonic and optoelectronic applications. Self-assembled porous alumina structures were obtained. These structures were fabricated by electrochemical technique (anodization of aluminum substrates). The effects of acid type and anodizing voltage on the formation of porous alumina film were analyzed. It was discussed the possible mechanism of self-assembled pores formation.
Reactive Ion Etching of Polyscrystalline Silicon Using Thinning Technology in Fluorine Based Mixtures
Authors: Nunes A. M. , Moshkalyov S. A. , Tatsch P. J. , Daltrini A. M.
Published: November 2007

This work presents the results of the study of etching profile evolution using the thinning technology for Si-poly structures with SF6/CF4/CHF3 gas mixtures. Structures with a aspect ratio (height/width) up to 5 and widths in the range of 0.1 - 0.3 μm were produced. High anisotropy of etched Si-poly structures (anisotropy factor up to 0.92-0.98) was demostrated. The method can be used for fabrication of sub-micron Si-poly gates in CMOS.
Study of the Silicon Etch Rate and Mechanisms When Using Aluminium, Tin and Copper Electrodes
Authors: Verdonck Patrick , Ruas Ronaldo
Published: November 2007

Silicon plasma etching is an important technique in the fabrication of integrated circuits and micro-electronic-mechanical systems. The influence of three electrode materials, aluminium, tin and copper, on the silicon etch rate was studied in a capacitively coupled plasma system. When applying SF6 plasmas, the etch rate was, in general, highest when using a tin electrode and lowest with a copper electrode. But with a CF4 plasma, the etch rate was highest for the aluminium electrode and lowest for the tin electrode. Rutherford Backscattering Spectroscopy indicated that for both plasmas, a very thin and stable aluminium fluoride film was formed on the aluminium electrode; for SF6 plasmas, S was adsorbed or absorbed by the tin electrode, liberating more free fluorine, while copper consumed fluorine and for CF4 plasmas, both copper and tin electrodes consumed fluorine. These mechanisms could explain the differences in the silicon etch rates for the three electrode materials.
Global Model in Low-Pressure Oxygen Discharges
Authors: Roberson Geraldo , Roberto Marisa , Verboncoeu John , Minnich Austin
Published: November 2007

We use a global model (volume averaged) to study plasma discharges in molecular oxygen gas in the pressure range of 1- 78 mTorr. This model determines positive ions O2+, O+, negative ion O-, and electron densities, ground state O2 and O atoms and metastable O2(a1Δg) and O(1D) densities, and electron temperature as function of gas pressure and input power, for a cylindrical discharge. We apply the model to O2 discharges and the results are compared to experimental data and a more elaborated volume-averaged global model developed at the University of California at Berkeley.
Efficiency of autoregulatory homeostatic responses to imposed caloric excess in lean men
Authors: Siervo Mario , Frühbeck Gema , Dixon Adrian , Goldberg Gail R. , Coward W. Andy , Murgatroyd Peter R. , Prentice Andrew M. , Jebb Susan A.
Published: November 2007

Obesity implies a failure of autoregulatory homeostatic responses to caloric excess. We studied the mechanisms, effectiveness, and limits of such responses in six lean (21.9 ± 1.3 kg/m2), healthy men based in a metabolic suite for 17 wk of progressive intermittent overfeeding (OF) (3 wk, baseline; 3 wk, 20% OF; 1 wk, ad libitum; 3 wk, 40% OF; 1 wk, ad libitum; 3 wk, 60% OF; 3 wk, ad libitum). Body composition was assessed by a four-compartment model using dual X-ray absorptiometry, deuterium dilution, and plethysmography. Magnetic resonance imaging assessed subcutaneous/visceral fat at abdominal level at baseline and at the end of 60% OF. Energy intake was assessed throughout, energy expenditure (EE) and substrate oxidation rates were measured repeatedly by whole body calorimetry (calEE), and free-living EE (TEE) was measured by doubly labeled water at baseline and after 60% OF. At the end of 60% OF, calEE and TEE had increased by just 11.4% ( P = 0.001) and 16.2% ( P = 0.001), respectively. Weight and body fat (fat mass) had increased by 5.98 kg (8.8%, P = 0.001) and 3.31 kg (22.6%, P = 0.01), respectively. The relative increase in visceral fat (32.6%, P = 0.02) exceeded that of subcutaneous fat (13.3%, P = 0.002) in the abdominal region. The computed energy cost of tissue accretion differed from the excess ingested by only 13.1% (using calEE) and 11.6% (using TEE), indicating an absence of effective dissipative mechanisms. We conclude that elevations in EE provide very limited autoregulatory capacity in body weight regulation, and that regulation must be dominated by hypothalamic modulation of energy intake. This result supports present conclusions from genetic studies in which all known causes of human obesity are related to defects in the regulation of appetite.
On the Classification Capability of Sign-Constrained Perceptrons
Authors: Legenstein Robert , Maass Wolfgang
Published: November 2007

The perceptron (also referred to as McCulloch-Pitts neuron, or linear threshold gate) is commonly used as a simplified model for the discrimination and learning capability of a biological neuron. Criteria that tell us when a perceptron can implement (or learn to implement) all possible dichotomies over a given set of input patterns are well known, but only for the idealized case, where one assumes that the sign of a synaptic weight can be switched during learning. We present in this letter an analysis of the classification capability of the biologically more realistic model of a sign-constrained perceptron, where the signs of synaptic weights remain fixed during learning (which is the case for most types of biological synapses). In particular, the VC-dimension of sign-constrained perceptrons is determined, and a necessary and sufficient criterion is provided that tells us when all 2m dichotomies over a given set of m patterns can be learned by a sign-constrained perceptron. We also show that uniformity of L1 norms of input patterns is a sufficient condition for full representation power in the case where all weights are required to be nonnegative. Finally, we exhibit cases where the sign constraint of a perceptron drastically reduces its classification capability. Our theoretical analysis is complemented by computer simulations, which demonstrate in particular that sparse input patterns improve the classification capability of sign-constrained perceptrons.
Politics as Usual or Bringing Religion Back In?
Authors: Fink Simon
Published: November 2007

This article explains the variation of embryo research laws in the Western world. A quantitative analysis shows that theories of partisan influence, institutions, and economic interests are ill suited to explain this variation. Only when cultural factors are considered can the variation be explained. Catholic societies legislate more strictly, and the Catholic Church is an influential actor. This is surprising, as economic interests are very important in the field. But even in a field where the economic stakes are high, the Catholic Church can be successful. The lessons are twofold. First, the discussion about the determinants of embryo research policies is enriched, as the article shows that despite particular discourses, religion is still a major factor and that the field can be fruitfully analyzed using a quantitative approach. Second, the article claims that theories of comparative public policy can benefit from the inclusion of cultural factors.
Original and Derived Judgment: An Entrepreneurial Theory of Economic Organization
Authors: Foss Kirsten , Foss Nicolai J. , Klein Peter G.
Published: November 2007

Recent work links entrepreneurship to the economic theory of the firm, using the concept of entrepreneurship as judgment introduced by Frank Knight. When judgment is complementary to other assets, it makes sense for entrepreneurs to hire labour and to own assets. The entrepreneur's role, then, is to arrange or organize the human and capital assets under his or her control. We extend this Knightian concept of the firm by developing a theory of delegation under Knightian uncetainty. What we call original judgment belongs exclusively to owners, but owners may delegate a wide range of decision rights to subordinates, who exercise derived judgment. We call these employees `proxy-entrepreneurs', and ask how the firm's organizational structure — its formal and informal systems of rewards and punishments, rules for settling disputes and renegotiating agreements, means of evaluating performance and so on — can be designed to encourage forms of proxy entrepreneurship that increase firm value while discouraging actions that destroy value. Building on key ideas from the entrepreneurship literature, Austrian economics and the economic theory of the firm, we develop a framework for analysing the trade-off between productive and destructive proxy entrepreneurship. We link this analysis to the employment relation and ownership structure, providing new insights into these and related issues in the economic theory of the firm.
Promoting the President's Foreign Policy Agenda
Authors: Caruson Kiki , Farrar-Myers Victoria A.
Published: November 2007

Executive agreements represent a powerful tool for pursuing commitments with other nations across the spectrum of foreign policy issues. In particular, the executive agreement gives presidents the flexibility to act independently of Congress. The authors' research demonstrates, quantitatively, how presidents use international executive agreements to advance their foreign policy priorities. The authors evaluate the foreign policy agendas of the Carter, Reagan, G. H. W. Bush, and first Clinton administrations and test whether the executive agreements signed during each administration serve to further the individual foreign policy goals of each president. The authors find that presidents are more likely to devote personal attention to an agreement that furthers a specific policy priority, and they identify greater agreement activity in areas that correspond to presidential initiatives.
How Federal and State Policies Affected Hospital Uncompensated Care Provision in the 1990s
Authors: Lo Sasso Anthony T. , Seamster Dorian G.
Published: November 2007

The 1990s featured pronounced policy change that had important effects on safety net providers and their ability to care for the uninsured. The authors examined how changes in public policy affected hospital uncompensated care (UC) between 1990 and 2000. They found that aggregate state Medicaid Disproportionate Share Hospital spending had no impact on UC provision. Expanding public health insurance eligibility for children and adults and increasing Medicaid managed care had small negative effects on UC provision. State and local tax appropriations had the largest impact on UC provision. A better understanding of the effect of health care policies on UC provision is essential in crafting new policies and better anticipating their impact.
Splenic red pulp lymphoma with numerous basophilic villous lymphocytes: a distinct clinicopathologic and molecular entity?
Authors: Traverse-Glehen Alexandra , Baseggio Lucile , Bauchu Evelyne Callet- , Morel Dominique , Gazzo Sophie , Ffrench Martine , Verney Aurélie , Rolland Delphine , Thieblemont Catherine , Magaud Jean-Pierre , Salles Gilles , Coiffier Bertrand , Berger Françoise , Felman Pascale
Published: November 2007

The presence of circulating villous lymphocytes (VLs) in lymphoma patients usually points to splenic marginal zone B-cell lymphoma (SMZL), even if the VLs can be found occasionally in other small B-cell lymphomas. However, those cells are variably described, and detailed cytologic characterization is often lacking. We identified lymphoma cases with numerous basophilic VLs among the large group of splenic lymphoma with VLs, and for further delineation, 37 cases with this particular cytology were analyzed. Patients, predominantly older men, presented with moderate lymphocytosis and splenomegaly without pancytopenia. The monoclonal B cells expressed IgM + D, IgM + G, IgM or IgG, as well as CD76 and CD11c, frequently CD103, and rarely CD123. Spleen sections were peculiar, with atrophic white pulp and a monomorphic diffuse lymphoma infiltration in a congested red pulp. Bone marrow infiltration was interstitial and intrasinusoidal without extensive fibrosis. Cytogenetic analysis showed a frequent absence of clonal aberrations (68%). Most cases (79%) were IgH mutated, with an overrepresentation of VH3 and VH4 gene families. These results, as well as the clinical evolution, show that those lymphoma cases represent a homogeneous group distinct from SMZL and reminiscent of hairy cell leukemia variant, perhaps corresponding to a separate lymphoma entity.
Complex inheritance pattern of dyskeratosis congenita in two families with 2 different mutations in the telomerase reverse transcriptase gene
Authors: Du Hong-Yan , Pumbo Elena , Manley Peter , Field Joshua J. , Bayliss Susan J. , Wilson David B. , Mason Philip J. , Bessler Monica
Published: November 2007

Heterozygous mutations in the telomerase components TERT, the reverse transcriptase, and TERC, the RNA template, cause autosomal dominant dyskeratosis congenita due to telomere shortening. Anticipation, whereby the disease severity increases in succeeding generations due to inheritance of shorter telomeres, is a feature of this condition. Here we describe 2 families in which 2 TERT mutations are segregating. Both families contain compound heterozygotes. In one case the proband is homozygous for a novel mutation causing a P704S substitution, while his father's second allele encodes an H412Y mutation. The proband in the second family has mutant alleles Y846C and H876Q. Transfection studies show codominant expression of the mutated alleles with no evidence of a dominant negative effect or of intragenic complementation. Thus in these families the expression of both TERT alleles and the inherited telomere length contribute to the clinical phenotype.
Ocular pathology of uncommon hematologic malignancies: a case series
Authors: Head James E , Shen Defen , Santiago-Maysonet Maribel , Bishop Rachel J , Chan Chi-Chao
Published: November 2007

Introduction

In general, ocular complications of hematologic malignancies such as leukemia are well documented. However, reports of ocular involvement in such diseases as lymphomatoid granulomatosis and chronic myelomonocytic leukemia are uncommon. Here we present cases of these two relatively rare hematologic malignancies demonstrating clinical and subclinical ocular involvement.

Case Presentation

In the first case, a 54-year-old man with a previous diagnosis of lymphomatoid granulomatosis presented with a new-onset conjunctival lesion while his systemic disease was thought to be in remission. A biopsy was taken that revealed heavy infiltrates of B and T cells at the site of the lesion. Molecular analysis confirmed that these cells were positive for both Epstein-Barr viral DNA and immunoglobulin heavy chain gene rearrangement, consistent with a manifestation of his systemic disease. In the second case, a 51-year-old man with chronic myelomonocytic leukemia died after a waxing and waning clinical course. Post-mortem studies revealed the presence of atypical monocytes in the choroidal and subretinal spaces, consistent with his previous diagnosis.

Conclusion

While ocular involvement in hematologic malignancies is not uncommon, these two cases describe involvement of the eye by two relatively rare neoplasms. We herein emphasize novel findings in each case, including conjunctival involvement as the first sign of recurrent lymphomatoid granulomatosis and the combination of subretinal and choroidal myelomonocytic leukemic infiltration. With the evolution of new antineoplastic therapies that may prolong life, these cases exemplify the importance of eye care in patients diagnosed with hematologic malignancies.
Integrative analysis for finding genes and networks involved in diabetes and other complex diseases
Authors: Bergholdt Regine , Størling Zenia M , Lage Kasper , Karlberg E Olof , Ólason Páll Í , Aalund Mogens , Nerup Jørn , Brunak Søren , Workman Christopher T , Pociot Flemming
Published: November 2007

We have developed an integrative analysis method combining genetic interactions, identified using type 1 diabetes genome scan data, and a high-confidence human protein interaction network. Resulting networks were ranked by the significance of the enrichment of proteins from interacting regions. We identified a number of new protein network modules and novel candidate genes/proteins for type 1 diabetes. We propose this type of integrative analysis as a general method for the elucidation of genes and networks involved in diabetes and other complex diseases.
Characterization of Pathogenic Human MSH2 Missense Mutations Using Yeast as a Model System: A Laboratory Course in Molecular Biology
Authors: Gammie Alison E. , Erdeniz Naz
Published: November 2007

This work describes the project for an advanced undergraduate laboratory course in cell and molecular biology. One objective of the course is to teach students a variety of cellular and molecular techniques while conducting original research. A second objective is to provide instruction in science writing and data presentation by requiring comprehensive laboratory reports modeled on the primary literature. The project for the course focuses on a gene, MSH2, implicated in the most common form of inherited colorectal cancer. Msh2 is important for maintaining the fidelity of genetic material where it functions as an important component of the DNA mismatch repair machinery. The goal of the project has two parts. The first part is to create mapped missense mutation listed in the human databases in the cognate yeast MSH2 gene and to assay for defects in DNA mismatch repair. The second part of the course is directed towards understanding in what way are the variant proteins defective for mismatch repair. Protein levels are analyzed to determine if the missense alleles display decreased expression. Furthermore, the students establish whether the Msh2p variants are properly localized to the nucleus using indirect immunofluorescence and whether the altered proteins have lost their ability to interact with other subunits of the MMR complex by creating recombinant DNA molecules and employing the yeast 2-hybrid assay.
Brains Rule!: A Model Program for Developing Professional Stewardship among Neuroscientists
Authors: Zardetto-Smith Andrea M. , Mu Keli , Carruth Laura L. , Frantz Kyle J.
Published: November 2007

Brains Rule! Neuroscience Expositions, funded through a National Institute on Drug Abuse Science Education Drug Abuse Partnership Award, has developed a successful model for informal neuroscience education. Each Exposition is a “reverse science fair” in which neuroscientists present short neuroscience teaching modules to students. This study focuses on results of assessments conducted with neuroscientist presenters during Expositions at two sites, Atlanta, Georgia and Corpus Christi, Texas. The effects of participating in the Expositions on presenters' perceptions of their own presentation and communication skills were evaluated, as was the potential for increased active participation by neuroscientists in future outreach programs. In four of the five Expositions studied, pre- versus post-event surveys demonstrated significant changes in presenters' perceptions of their own abilities to explain neuroscience concepts to children. Over the course of an Exposition, presenters learned to fit their approaches to conveying neuroscience concepts to fifth through eighth graders and learned to link information they presented about the brain and nervous system to children's past experiences to improve comprehension. The present data suggest that Brains Rule! Neuroscience Expositions are effective in improving communication and teaching skills among neuroscience professionals and contribute to professional stewardship by increasing motivation to participate in future informal education programs.
Enhancing Undergraduate Teaching and Research with aDrosophilaVirginizing System
Authors: Venema Dennis R.
Published: November 2007

Laboratory exercises using Drosophila crosses are an effective pedagogical method to complement traditional lecture and textbook presentations of genetics. Undergraduate thesis research is another common setting for using Drosophila. A significant barrier to using Drosophila for undergraduate teaching or research is the time and skill required to accurately collect virgins for use in controlled crosses. Erroneously collecting males or nonvirgin females contaminates crosses with unintended genotypes and confounds the results. Collecting adequate numbers of virgins requires large amounts of time, even for those skilled in virgin collection. I have adapted an effective method for virgin collection that eliminates these concerns and is straightforward to use in undergraduate settings. Using a heat-shock–induced, conditional lethal transgene specifically in males, male larvae can be eliminated from a culture before adults eclose. Females thus eclose in the absence of males and remain virgin, eliminating the need to laboriously score and segregate freshly eclosed females. This method is reliable, easily adaptable to any desired phenotypic marker, and readily scaleable to provide sufficient virgins for large laboratory classes or undergraduate research projects. In addition, it allows instructors lacking Drosophila expertise to use this organism as a pedagogical tool.
Collaborative Co-Mentored Dissertations Spanning Institutions: Influences on Student Development
Authors: McGee Richard , DeLong Mary J.
Published: November 2007

The Graduate Partnerships Program (GPP), established in 2000, links universities with National Institutes of Health (NIH) laboratories for predoctoral training. Several partnerships required that students create collaborative dissertations between at least one NIH and one university research mentor. More than 60 students have entered into these co-mentored research collaborations, and many others established them even though not required. Much was learned about the experiences of these and other GPP students by using structured interviews as part of a formal self-study of the GPP in 2005. Complications of trying to work with two mentors are managed through careful program design and mentor selection. In the collaborative model, students develop a complex set of scientific and interpersonal skills. They lead their own independent research projects, drawing on the expertise of multiple mentors and acquiring skills at negotiating everyone's interests. They develop high levels of independence, maturity, flexibility, and the ability to see research questions from different perspectives. No evidence was found that co-mentoring diminishes the normally expected accomplishments of a student during the Ph.D. Multi-mentored dissertations require skills not all graduate students may possess this early in training, but for those who do, they can promote rapid and extensive development of skills needed for collaborative, interdisciplinary research.
WormClassroom.org: An Inquiry-rich Educational Web Portal for Research Resources of Caenorhabditis elegans
Authors: Lu Fong-Mei , Eliceiri Kevin W. , Stewart James , White John G.
Published: November 2007

The utilization of biology research resources, coupled with a “learning by inquiry” approach, has great potential to aid students in gaining an understanding of fundamental biological principles. To help realize this potential, we have developed a Web portal for undergraduate biology education, WormClassroom.org, based on current research resources of a model research organism, Caenorhabditis elegans. This portal is intended to serve as a resource gateway for students to learn biological concepts using C. elegans research material. The driving forces behind the WormClassroom website were the strengths of C. elegans as a teaching organism, getting researchers and educators to work together to develop instructional materials, and the 3 P's (problem posing, problem solving, and peer persuasion) approach for inquiry learning. Iterative assessment is an important aspect of the WormClassroom site development because it not only ensures that content is up-to-date and accurate, but also verifies that it does, in fact, aid student learning. A primary assessment was performed to refine the WormClassroom website utilizing undergraduate biology students and nonstudent experts such as C. elegans researchers; results and comments were used for site improvement. We are actively encouraging continued resource contributions from the C. elegans research and education community for the further development of WormClassroom.
The Value of Animations in Biology Teaching: A Study of Long-Term Memory Retention
Authors: O'Day Danton H.
Published: November 2007

Previous work has established that a narrated animation is more effective at communicating a complex biological process (signal transduction) than the equivalent graphic with figure legend. To my knowledge, no study has been done in any subject area on the effectiveness of animations versus graphics in the long-term retention of information, a primary and critical issue in studies of teaching and learning. In this study, involving 393 student responses, three different animations and two graphics—one with and one lacking a legend—were used to determine the long-term retention of information. The results show that students retain more information 21 d after viewing an animation without narration compared with an equivalent graphic whether or not that graphic had a legend. Students' comments provide additional insight into the value of animations in the pedagogical process, and suggestions for future work are proposed.
Multiple Encounter Simulation for High‐acuity Multipatient Environment Training
Authors: Kobayashi Leo , Shapiro Marc J. , Gutman Deborah C. , Jay Gregory
Published: November 2007

Patient safety interventions for multitasking, multipatient, error‐prone work settings such as the emergency department (ED) must improve assorted clinical abilities, specific cognitive strategies, and teamwork functions of the staff to be effective. Multiple encounter simulation scenarios explore and convey this specialized mental work‐set through use of multiple high‐fidelity medical simulation (SIM) manikins in realistic surroundings. Multipatient scenarios reflect the work situations being targeted yet have the benefit of scripted control and instructor guidance to advance specific educational objectives. The use of two or more SIM patients promotes the exploration not only of multiple distinct clinical issues but also of interdependent processes pervasive in EDs. Cascading shortages of time, personnel, equipment, and supplies are re‐created, thereby replicating process limitations at various levels, in a safe environment in which compensatory actions and adaptive behaviors can be learned. Distinguishing features of multipatient exercises include 1) broadened educational scope and expanded indications for SIM application, 2) enhanced scenario complexity, 3) controlled exposure to high workload environments, 4) expanded communication requirements, and 5) increased potential for reflective learning. Widespread and effective training in well‐replicated, carefully coordinated representations of complex multipatient work environments may strengthen educational interventions for personnel working in high acuity and work‐overloaded settings such as the ED. The use of concurrent patient encounter SIM exercises to elicit calculated stressors and to foster compensatory staff behaviors is an educational advance toward this objective. The authors present SIM methodology using concurrent patient encounters to replicate these environments.
Distinguishing between retention signals and degrons acting in ERAD
Authors: Shapira Ilana , Charuvi Dana , Elkabetz Yechiel , Hirschberg Koret , Bar-Nun Shoshana
Published: November 2007

Endoplasmic reticulum-associated degradation (ERAD) eliminates aberrant proteins from the secretory pathway. Such proteins are retained in the endoplasmic reticulum and targeted for degradation by the ubiquitin-proteasome system. Cis-acting motifs can function in ERAD as retention signals, preventing vesicular export from the endoplasmic reticulum, or as degrons, targeting proteins for degradation. Here, we show that μstp, the C-terminal 20-residue tailpiece of the secretory IgM μs heavy chain, functions both as a portable retention signal and as an ERAD degron. Retention of μstp fusions of secreted versions of thyroid peroxidase and yellow fluorescent protein in the endoplasmic reticulum requires the presence of the penultimate cysteine of μstp. In its role as a portable degron, the μstp targets the retained proteins for ERAD but does not serve as an obligatory ubiquitin-conjugation site. Abolishing μstp glycosylation accelerates the degradation of both μstpCys-fused substrates, yet absence of the N-glycan eliminates the requirement for the penultimate cysteine in the retention and degradation of the unglycosylated yellow fluorescent protein. Hence, the dual role played by the μstpCys motif as a retention signal and as a degron can be attributed to distinct elements within this sequence.
Cdk5 regulates differentiation of oligodendrocyte precursor cells through the direct phosphorylation of paxillin
Authors: Miyamoto Yuki , Yamauchi Junji , Chan Jonah R. , Okada Atsumasa , Tomooka Yasuhiro , Hisanaga Shin-ichi , Tanoue Akito
Published: November 2007

Oligodendrocyte precursor cells (OPCs) differentiate into oligodendrocytes (OLs) in order to form myelin, which is required for the rapid propagation of action potentials in the vertebrate nervous system. In spite of the considerable clinical importance of myelination, little is known about the basic molecular mechanisms underlying OL differentiation and myelination. Here, we show that cyclin-dependent kinase (Cdk) 5 is activated following the induction of differentiation, and that the Cdk5 inhibitor roscovitine inhibits OL differentiation. The complexity of the OL processes is also diminished after knocking down endogenous Cdk5 using RNAi. We also show that the focal adhesion protein paxillin is directly phosphorylated at Ser244 by Cdk5. Transfection of a paxillin construct harboring a Ser244 to Ala mutation dramatically inhibits its morphological effects. Importantly, phosphorylation of paxillin at Ser244 reduces its interaction with focal adhesion kinase (FAK). Taken together, these results suggest that phosphorylation of paxillin by Cdk5 is a key mechanism in OL differentiation and may ultimately regulate myelination.