bluuebunny/crossref_metadata_2025 huggingface dataset:
Polyandrous females acquire indirect benefits in a nuptial feeding species
Authors: Tuni C. , Albo M. J. , Bilde T.
Published: May 2013

The relative force of direct and indirect selection underlying the evolution of polyandry is contentious. When females acquire direct benefits during mating, indirect benefits are often considered negligible. Although direct benefits are likely to play a prominent role in the evolution of polyandry, post‐mating selection for indirect benefits may subsequently evolve. We examined whether polyandrous females acquire indirect benefits and quantified direct and indirect effects of multiple mating on female fitness in a nuptial gift‐giving spider (Pisaura mirabilis). In this system, the food item donated by males during mating predicts direct benefits of polyandry. We compared fecundity, fertility and survival of singly mated females to that of females mated three times with the same (monogamy) or different (polyandry) males in a two‐factorial design where females were kept under high and low feeding conditions. Greater access to nutrients and sperm had surprisingly little positive effect on fitness, apart from shortening the time until oviposition. In contrast, polyandry increased female reproductive success by increasing the probability of oviposition, and egg hatching success indicating that indirect benefits arise from mating with several different mating partners rather than resources transferred by males. The evolution of polyandry in a male‐resource‐based mating system may result from exploitation of the female foraging motivation and that indirect genetic benefits are subsequently derived resulting from co‐evolutionary post‐mating processes to gain a reproductive advantage or to counter costs of mating. Importantly, indirect benefits may represent an additional explanation for the maintenance of polyandry.
Co‐evolutionary patterns and diversification of ant–fungus associations in the asexual fungus‐farming ant Mycocepurus smithii in Panama
Authors: Kellner K. , Fernández‐Marín H. , Ishak H. D. , Sen R. , Linksvayer T. A. , Mueller U. G.
Published: May 2013

Partner fidelity through vertical symbiont transmission is thought to be the primary mechanism stabilizing cooperation in the mutualism between fungus‐farming (attine) ants and their cultivated fungal symbionts. An alternate or additional mechanism could be adaptive partner or symbiont choice mediating horizontal cultivar transmission or de novo domestication of free‐living fungi. Using microsatellite genotyping for the attine ant Mycocepurus smithii and ITS rDNA sequencing for fungal cultivars, we provide the first detailed population genetic analysis of local ant–fungus associations to test for the relative importance of vertical vs. horizontal transmission in a single attine species. M. smithii is the only known asexual attine ant, and it is furthermore exceptional because it cultivates a far greater cultivar diversity than any other attine ant. Cultivar switching could permit the ants to re‐acquire cultivars after garden loss, to purge inferior cultivars that are locally mal‐adapted or that accumulated deleterious mutations under long‐term asexuality. Compared to other attine ants, symbiont choice and local adaptation of ant–fungus combinations may play a more important role than partner‐fidelity feedback in the co‐evolutionary process of M. smithii and its fungal symbionts.
Biotype Change for the Esthetic Rehabilitation of the Smile
Authors: Polack Mariano A. , Mahn Douglas H.
Published: May 2013

An esthetic and natural appearing smile is the result of multiple important factors. There must be a harmonious relation between tooth size, shape, proportion, and the periodontium. Successful rehabilitation of a smile often requires an interdisciplinary approach which was applied in the case presented in this article to a patient with multiple esthetic challenges. Treatment included management of canines in the lateral incisor positions, proportionally small teeth, and excessive gingival display. Good communication and coordination of care between the surgical and restorative partners produced a pleasing outcome facilitated by periodontal surgery resulting in a modification of the gingival biotype.

Clinical Significance

Smile design including crown lengthening and biotype modification can be used to create an esthetic and natural appearing restorative result.
Clinical Outcomes of Implant Abutments in the Anterior Region: A Systematic Review
Authors: Bidra Avinash S. , Rungruanganunt Patchanee
Published: May 2013

Statement of Problem

The clinical outcomes of anterior implant abutments are not well reported.

Purpose of the Study

To systematically review the existing literature to identify survival, mechanical, biological, and esthetic outcomes of anterior implant abutments.

Material and Methods

An electronic search was performed using PubMed/MEDLINE with specific search terms and predetermined criteria. After application of inclusion and exclusion criteria, the final list of articles was reviewed in‐depth to meet the objectives of this review.

Results

Systematic application of inclusion and exclusion criteria resulted in identification of 27 studies that described outcomes of anterior implant abutments. Because of substantial heterogeneity of data, true survival, or cumulative survival of abutments could not be calculated. However, the mean failure of abutments was 1.15%, attributable to fractures restricted to ceramic abutments. Mechanical complications included abutment screw loosening, primarily restricted to external hex implants. Biological complications included fistulas and mucosal recession. Esthetic outcomes showed lesser gingival discoloration for zirconia abutments compared with metal abutments.

Conclusions

Minimal anterior abutment fractures have been reported and are restricted to ceramic abutments. Studies using spectrophotometry showed lesser gingival discoloration with zirconia abutments, but there is no evidence for difference in patient's esthetic satisfaction between ceramic and metal abutments.

Clinical Significance

For the anterior region, selection of an implant with internal connection and a customized metal abutment (titanium or cast metal) can have the least mechanical complications. Limited existing clinical data indicate reduced peri‐implant mucosal discoloration from zirconia abutments, which may be preferable over metal abutments, in patients with thinner mucosal tissues or patients with high or gummy smiles.
Voluntary Contributions with Risky and Uncertain Marginal Returns: The Importance of the Parameter Values
Authors: LEVATI M. VITTORIA , MORONE ANDREA
Published: May 2013

Previous research indicates that risky and uncertain marginal returns from a public good lower contributions significantly. This paper presents experimental results showing that this effect depends on the employed parameterization.
Optimal  Incentive  Schemes  for  Altruistic Providers
Authors: MAKRIS MILTIADIS , SICILIANI LUIGI
Published: May 2013

We study the optimal design of incentive schemes in the presence of adverse selection and altruistic providers. We assume that providers differ in efficiency, are partially altruistic, and have limited liability. Three types of separating equilibrium emerge. (1) For low levels of altruism the quantity of the efficient and inefficient types is distorted upwards and downwards, respectively; the inefficient type makes zero profits. (2) For moderate levels of altruism the first best is attained: no distortions and profits are zero. (3) For high levels of altruism the quantity of the inefficient type is distorted upwards, and the quantity of the efficient type is distorted either upwards or downwards; the efficient type makes zero profits. Our main result is that the first best can be obtained for some values of altruism, but not necessarily for the highest values. The purchaser is better off with providers with moderate rather than high altruism.
Competitive Permit Markets and Vertical Structures: The Relevance of Imperfectly Competitive Eco‐Industries
Authors: SCHWARTZ SONIA , STAHN HUBERT
Published: May 2013

Permit markets lead polluting firms to purchase abatement goods from an eco‐industry which is often concentrated. This paper studies the consequences of this sort of imperfectly competitive eco‐industry on the equilibrium choices of the competitive polluting firms. It then characterizes the second‐best pollution cap. By comparing this situation to one of perfect competition, we show that Cournot competition on the abatement good market contributes not only to a nonoptimal level of emission reduction but also to a higher permit price, which reduces the production level. These distortions increase with market power, measured by the margin taken by the noncompetitive firms, and suggest a second‐best larger pollution cap.
Developing Country Second‐Mover Advantage in Competition Over Environmental Standards and Taxes
Authors: GROENERT VALESKA , ZISSIMOS BEN
Published: May 2013

We show that, in competition between a developed country and a developing country over environmental standards and taxes, the developing country may have a “second‐mover advantage.” In our model, firms do not unanimously prefer lower environmental standard levels. We introduce this feature to an otherwise familiar model of fiscal competition. Four distinct outcomes can be characterized by varying the marginal cost to firms of an environmental externality: (1) the outcome may be efficient; (2) the developing country may be a “pollution haven”—a place to escape excessively high environmental standards in the developed country; (3) the developing country may “undercut” the developed country and attract all firms; (4) the developed country may be a pollution haven.
Neuroanatomical asymmetries and handedness in chimpanzees (Pan troglodytes): a case for continuity in the evolution of hemispheric specialization
Authors: Hopkins William D.
Published: May 2013

Many historical and contemporary theorists have proposed that population‐level behavioral and brain asymmetries are unique to humans and evolved as a consequence of human‐specific adaptations such as language, tool manufacture and use, and bipedalism. Recent studies in nonhuman animals, notably primates, have begun to challenge this view. Here, I summarize comparative data on neuroanatomical asymmetries in the planum temporale (PT) and inferior frontal gyrus (IFG) of humans and chimpanzees, regions considered the morphological equivalents to Broca's and Wernicke's areas. I also review evidence of population‐level handedness in captive and wild chimpanzees. When similar methods and landmarks are used to define the PT and IFG, humans and chimpanzees show similar patterns of asymmetry in both cortical regions, though humans show more pronounced directional biases. Similarly, there is good evidence that chimpanzees show population‐level handedness, though, again, the expression of handedness is less robust compared to humans. These results stand in contrast to reported claims of significant differences in the distribution of handedness in humans and chimpanzees, and I discuss some possible explanations for the discrepancies in the neuroanatomical and behavioral data.
You Can't Make Me Do It: State Implementation of Insurance Exchanges under the Affordable Care Act
Authors: Haeder Simon F. , Weimer David L.
Published: May 2013

The Patient Protection and Affordable Care Act (ACA) of 2010 has been one of the most controversial laws in decades. The ACA relies extensively on the cooperation of states for its implementation, offering opportunities for both local adaptation and political roadblocks. Health insurance exchanges are one of the most important components of the ACA for achieving its goal of near‐universal coverage. Despite significant financial support from the federal government, many governors and legislatures have taken actions that have blocked or delayed significant progress in developing their exchanges. However, many state commissioners of insurance have played constructive roles in moving states forward in exchange planning through their expertise, leadership, and pragmatism, sometimes in spite of strong political opposition to the ACA from governors and legislatures.
Is Landau Damping Possible in a Shear Fluid Flow?
Authors: Chesnokov A. A. , Khe A. K.
Published: May 2013

Asymptotic analysis for small long‐wave perturbations of a given stationary shear flow of an ideal fluid with free boundary as is performed. It is shown that small disturbances of the flow are attracted to periodic solution in the case where the governing equations are hyperbolic on the main shear flow solution. A class of shear flows for which Landau damping is realizable, is described. Analytical results obtained are validated by numerical calculations.
Reterritorialization in the Micromediascape: Indonesian Regional Television amid the Rise of Normative Media‐Islam
Authors: Barkin Gareth
Published: May 2013

In Indonesia, national broadcasting in the 21st century has been characterized by increasing Muslim normativity across the spectrum of commercial programming, along with sectarian clashes that have further marginalized religious minorities. This article investigates the case of a small, regional television station in one of the country's Christian‐majority provinces to explore the ways that such minorities have exploited a relaxation of broadcast regulations to form distinctive and insular micromediascapes within the larger field of Indonesian media culture. I suggest the need for a more graduated articulation of Arjun Appadurai's “mediascape” concept that foregrounds the import of local, small‐scale production and broadcasting, particularly to marginalized groups. Based on an ethnographic study in Manado, North Sulawesi, I argue that local TV has risen to the foreground of the province's public culture in a manner that mobilizes its religious, ethnic, and historical identity narratives to reterritorialize audiences and reify the region's distinction from the state.
Upgrade and benchmarking of a 4D treatment planning system for scanned ion beam therapy
Authors: Richter D. , Schwarzkopf A. , Trautmann J. , Krämer M. , Durante M. , Jäkel O. , Bert C.
Published: May 2013

Purpose:

Upgrade and benchmarking of a research 4D treatment planning system (4DTPS) suitable for realistic patient treatment planning and treatment simulations taking into account specific requirements for scanned ion beam therapy, i.e., modeling of dose heterogeneities due to interplay effects and range changes caused by patient motion and dynamic beam delivery.

Methods:

The 4DTPS integrates data interfaces to 4D computed tomography (4DCT), deformable image registration and clinically used motion monitoring devices. The authors implemented a novel data model for 4D image segmentation using Boolean mask volume datasets and developed an algorithm propagating a manually contoured reference contour dataset to all 4DCT phases. They further included detailed treatment simulation and dose reconstruction functionality, based on the irregular patient motion and the temporal structure of the beam delivery. The treatment simulation functionality was validated against experimental data from irradiation of moving radiographic films in air, 3D moving ionization chambers in a water phantom, and moving cells in a biological phantom with a scanned carbon ion beam. The performance of the program was compared to results obtained with predecessor programs.

Results:

The measured optical density distributions of the radiographic films were reproduced by the simulations to (−2 ± 12)%. Compared to earlier versions of the 4DTPS, the mean agreement improved by 2%, standard deviations were reduced by 7%. The simulated dose to the moving ionization chambers in water showed an agreement with the measured dose of (−1 ± 4)% for the typical beam configuration. The mean deviation of the simulated from the measured biologically effective dose determined via cell survival was (617 ± 538) mGy relative biological effectiveness corresponding to (10 ± 9)%.

Conclusions:

The authors developed a research 4DTPS suitable for realistic treatment planning on patient data and capable of simulating dose delivery to a moving patient geometry for scanned ion beams. The accuracy and reliability of treatment simulations improved considerably with respect to earlier versions of the 4DTPS.
Multisensory Control of Hippocampal Spatiotemporal Selectivity
Authors: Ravassard Pascal , Kees Ashley , Willers Bernard , Ho David , Aharoni Daniel , Cushman Jesse , Aghajan Zahra M. , Mehta Mayank R.
Published: May 2013

A Sense of Place

Hippocampal place cells are believed to be mainly governed by visual and self-motion cues. However, the contribution of sensory cues such as smells, sounds, and textures, etc., is difficult to eliminate. In virtual reality, these cues will not provide any information about the animals' position.

Ravassard
et al.

(p.
1342
, published online 2 May) developed a virtual-reality system as immersive and close to the real world as possible and compared place cells in rats running in this apparatus and in the real world. Twice as many neurons were active in a real-world situation compared to virtual reality. While place cells in the real world encoded position, place cells in a virtual world encoded distance.
Shorter time until return of spontaneous circulation is the only independent factor for a good neurological outcome in patients with postcardiac arrest syndrome
Authors: Komatsu Tomohide , Kinoshita Kosaku , Sakurai Atsushi , Moriya Takashi , Yamaguchi Junko , Sugita Atsunori , Kogawa Rikimaru , Tanjoh Katsuhisa
Published: May 2013

Objective

Few studies have reported factors that result in a better neurological outcome in patients with postcardiac arrest syndrome (PCAS) following return of spontaneous circulation (ROSC). We investigated the factors affecting neurological outcome in terms of both prehospital care and treatments after arrival at hospital in patients with PCAS.

Methods

The study enrolled patients with cardiogenic cardiac arrest who were admitted to an intensive care unit after ROSC with PCAS. We investigated the association of the following factors with outcome: age, gender, witness to event present, bystander cardiopulmonary resuscitation (CPR) performed, ECG waveform at the scene, time interval from receipt of call to arrival of emergency personnel, time interval from receipt of call to arrival at hospital, prehospital defibrillation performed, special procedures performed by emergency medical technician, and time interval from receipt of call to ROSC, coronary angiography/percutaneous coronary intervention (PCI) and therapeutic hypothermia performed.

Results

The study enrolled 227 patients with PCAS. Compared with the poor neurological outcome group, the good neurological outcome group had a statistically significant higher proportion of the following factors: younger age, male, witness present, bystander CPR performed, first ECG showed ventricular fibrillation/pulseless ventricular tachycardia, defibrillation performed during transportation, short time interval from receipt of call to ROSC, coronary angiography/PCI and therapeutic hypothermia performed. Of these factors, the only independent factor associated with good neurological outcome was the short time interval from receipt of the call to ROSC.

Conclusions

In the present study, shortening time interval from receipt of call to ROSC was the only important independent factor to achieve good neurological outcome in patients with PCAS.
PARAMETERIZATION OF COARSE GRAINED FORCE FIELDS FOR DYNAMIC PROPERTY OF ETHYLENE GLYCOL OLIGOMERS/WATER BINARY MIXTURES
Authors: YAMAZAKI TAMIO
Published: May 2013

To evaluate shear viscosity of ethylene glycol oligomers (EGO)/water binary mixture by means of coarse-grained molecular dynamics (CG-MD) simulations, we proposed the self-diffusion-coefficient-based parameterization of non-bonded interactions among CG particles. Our parameterization procedure consists of three steps: (1) determination of bonded potentials, (2) scaling for time and solvent diffusivity and (3) optimization of Lennard-Jones parameters to reproduce experimental self-diffusion coefficient and density data. With the determined parameters and the scaling relations, we evaluated shear viscosities of aqueous solutions of EGOs with various molecular weights and concentrations. Our simulation results are in close agreement with the experimental data. The largest simulation in this article corresponds to a 1.2 μs atomistic simulation for 100,000 atoms. Our CG model with the parameterization scheme for CG particles may be useful to study the dynamic properties of a liquid which contains relatively low molecular weight polymers or oligomers.
RECENT RESEARCH ON TSUNAMI HAZARDS FOR SUMATRA AND THE SOUTH CHINA SEA AREA
Authors: HUANG ZHENHUA , WU TSO-REN , SYAMSIDIK
Published: May 2013

Some challenging issues in tsunami disaster mitigation and risk management are raised at the AIWEST-DR2011 in Conjunction with SCSTW-4. Currently there is no enough attention given to potential tsunamis in South China Sea due to the lack of data for historic tsunamis in the area, therefore there is a need to have a joint effort among the countries bordering the South China Sea to collect scientific evidence of historic tsunamis along the border of the South China Sea.
TOWARDS FFT-BASED DIRECT NUMERICAL SIMULATIONS OF TURBULENT FLOWS ON A GPU
Authors: RUCKI CATHERINE , CHANDY ABHILASH J.
Published: May 2013

The accurate simulation of turbulence and the implementation of corresponding turbulence models are both critical to the understanding of the complex physics behind turbulent flows in a variety of science and engineering applications. Despite the tremendous increase in the computing power of central processing units (CPUs), direct numerical simulation of highly turbulent flows is still not feasible due to the need for resolving the smallest length scale, and today's CPUs cannot keep pace with demand. The recent development of graphics processing units (GPU) has led to the general improvement in the performance of various algorithms. This study investigates the applicability of GPU technology in the context of fast-Fourier transform (FFT)-based pseudo-spectral methods for DNS of turbulent flows for the Taylor–Green vortex problem. They are implemented on a single GPU and a speedup of unto 31x is obtained in comparison to a single CPU.
Recovery efficiency from a turbidite sheet system: numerical simulation of waterflooding using outcrop-based geological models
Authors: Amy Lawrence A. , Peachey Simon A. , Gardiner Andy R. , Pickup Gillian E. , Mackay Eric , Stephen Karl D.
Published: May 2013

A series of waterflood simulations were performed to investigate the effect of basinal position and facies permeability within a turbidite sheet system on oil recovery efficiency. Simulations used three-dimensional outcrop models of the Peïra Cava system, comprising gravel, sandstone, thin-bedded heterolithic and mudstone facies.

Recovery efficiency declines with increasing permeability heterogeneity and is influenced by the interaction of vertical bed-permeability trends and flood-front gravity slumping. The occurrence of gravels with permeabilities lower than overlying sandstones produces optimum recoveries. High permeability gravels act as thief zones, enhanced by downward gravity slumping, reducing normalized recovery by up to 34 %. The effect of thief zones on recovery is related to their permeability contrast, abundance, thickness, lateral continuity, vertical position within permeable units and the permeability of underlying facies.

Proximal to distal stratigraphic variations produce relatively small differences in normalized recovery of up to 13 % in models with the highest permeability heterogeneity. Differences in recovery are interpreted to reflect spatial trends in facies architecture, which determine the effectiveness of high permeability gravel thief zones. The poorest recovery is recorded from the medial model where recovery is lower than distal areas because of higher gravel abundance and thicknesses and lower compared to proximal areas because of the higher lateral continuity of gravels and underlying low-permeability mudstones.
Sedimentology and sequence stratigraphy of the Middle–Upper Jurassic Krossfjord and Fensfjord formations, Troll Field, northern North Sea
Authors: Holgate Nicholas E. , Jackson Christopher A.-L. , Hampson Gary J. , Dreyer Tom
Published: May 2013

The Middle–Upper Jurassic Krossfjord and Fensfjord formations are secondary reservoir targets in the super-giant Troll oil and gas field, Horda Platform, offshore Norway. The formations comprise sandstones (
c
. 195 m thick) sourced from the Norwegian mainland to the east, that pinch out basinwards into offshore shales of the Heather Formation to the west. Sedimentological analysis of cores from the Troll Field has identified six facies associations, which represent wave- and tide-dominated deltaic, shoreline and shelf depositional environments. Resulting depositional models highlight the complex distribution of depositional environments, and reflect spatial and temporal variations in physical processes at the shoreline, rate of sediment supply and accommodation development. These models are further complicated by the absence of coastal plain facies, which implies that the Troll Field was fully subaqueous during deposition, that shoreline regression was forced by falling sea level or that coastal plain deposits were removed by transgression. Genetic sequences bounded by major flooding surfaces (‘series’) exhibit laterally uniform thicknesses, implying no major tectonic influence on sedimentation. The recognition of pronounced variability in facies character and stratigraphical architecture emphasize the need for a robust depositional model of the formations in order to drive future exploration in these, and coeval, reservoirs.
A practical microcylinder appearance model for cloth rendering
Authors: Sadeghi Iman , Bisker Oleg , De Deken Joachim , Jensen Henrik Wann
Published: May 2013

This article introduces a practical shading model for cloth that can simulate both anisotropic highlights as well as the complex color shifts seen in cloth made of different colored threads. Our model is based on extensive Bidirectional Reflectance Distribution Function (BRDF) measurements of several cloth samples. We have also measured the scattering profile of several different individual cloth threads. Based on these measurements, we derived an empirical shading model capable of predicting the light scattering profile of a variety of threads. From individual threads, we synthesized a woven cloth model, which provides an intuitive description of the layout of the constituent threads as well as their tangent directions. Our model is physically plausible, accounting for shadowing and masking by the threads. We validate our model by comparing predicted and measured light scattering values and show how it can reproduce the appearance of many cloth and thread types, including silk, velvet, linen, and polyester. The model is robust, easy to use, and can simulate the appearance of complex highlights and color shifts that cannot be fully handled by existing models.
Closest point turbulence for liquid surfaces
Authors: Kim Theodore , Tessendorf Jerry , Thürey Nils
Published: May 2013

We propose a method of increasing the apparent spatial resolution of an existing liquid simulation. Previous approaches to this “up-resing” problem have focused on increasing the turbulence of the underlying velocity field. Motivated by measurements in the free surface turbulence literature, we observe that past certain frequencies, it is sufficient to perform a wave simulation directly on the liquid surface, and construct a reduced-dimensional surface-only simulation. We sidestep the considerable problem of generating a surface parameterization by employing an embedding technique known as the
Closest Point Method
(CPM) that operates directly on a 3D extension field. The CPM requires 3D operators, and we show that for surface operators with no natural 3D generalization, it is possible to construct a viable operator using the
inverse Abel transform
. We additionally propose a fast,
frozen core
closest point transform, and an advection method for the extension field that reduces smearing considerably. Finally, we propose two turbulence coupling methods that seed the high-resolution wave simulation in visually expected regions.
Near-Optimal Microprocessor and Accelerators Codesign with Latency and Throughput Constraints
Authors: Kritikakou Angeliki , Catthoor Francky , Athanasiou George S. , Kelefouras Vasilios , Goutis Costas
Published: May 2013

A systematic methodology for near-optimal software/hardware codesign mapping onto an FPGA platform with microprocessor and HW accelerators is proposed. The mapping steps deal with the inter-organization, the foreground memory management, and the datapath mapping. A step is described by parameters and equations combined in a scalable template. Mapping decisions are propagated as design constraints to prune suboptimal options in next steps. Several performance-area Pareto points are produced by instantiating the parameters. To evaluate our methodology we map a real-time bio-imaging application and loop-dominated benchmarks.
Mining big data
Authors: Fan Wei , Bifet Albert
Published: May 2013

Big Data
is a new term used to identify datasets that we can not manage with current methodologies or data mining software tools due to their large size and complexity.
Big Data mining
is the capability of extracting useful information from these large datasets or streams of data. New mining techniques are necessary due to the volume, variability, and velocity, of such data. The Big Data challenge is becoming one of the most exciting opportunities for the years to come. We present in this issue, a broad overview of the topic, its current status, controversy, and a forecast to the future. We introduce four articles, written by influential scientists in the field, covering the most interesting and state-of-the-art topics on Big Data mining.
Mechanics in Neuronal Development and Repair
Authors: Franze Kristian , Janmey Paul A. , Guck Jochen
Published: May 2013

Biological cells are well known to respond to a multitude of chemical signals. In the nervous system, chemical signaling has been shown to be crucially involved in development, normal functioning, and disorders of neurons and glial cells. However, there are an increasing number of studies showing that these cells also respond to mechanical cues. Here, we summarize current knowledge about the mechanical properties of nervous tissue and its building blocks, review recent progress in methodology and understanding of cellular mechanosensitivity in the nervous system, and provide an outlook on the implications of neuromechanics for future developments in biomedical engineering to aid overcoming some of the most devastating and currently incurable CNS pathologies such as spinal cord injuries and multiple sclerosis.
Multiscale Computational Models of Complex Biological Systems
Authors: Walpole Joseph , Papin Jason A. , Peirce Shayn M.
Published: May 2013

Integration of data across spatial, temporal, and functional scales is a primary focus of biomedical engineering efforts. The advent of powerful computing platforms, coupled with quantitative data from high-throughput experimental methodologies, has allowed multiscale modeling to expand as a means to more comprehensively investigate biological phenomena in experimentally relevant ways. This review aims to highlight recently published multiscale models of biological systems, using their successes to propose the best practices for future model development. We demonstrate that coupling continuous and discrete systems best captures biological information across spatial scales by selecting modeling techniques that are suited to the task. Further, we suggest how to leverage these multiscale models to gain insight into biological systems using quantitative biomedical engineering methods to analyze data in nonintuitive ways. These topics are discussed with a focus on the future of the field, current challenges encountered, and opportunities yet to be realized.
Microfluidics and Coagulation Biology
Authors: Colace Thomas V. , Tormoen Garth W. , McCarty Owen J.T. , Diamond Scott L.
Published: May 2013

The study of blood ex vivo can occur in closed or open systems, with or without flow. Microfluidic devices, which constrain fluids to a small (typically submillimeter) scale, facilitate analysis of platelet function, coagulation biology, cellular biorheology, adhesion dynamics, and pharmacology and, as a result, can be an invaluable tool for clinical diagnostics. An experimental session can accommodate hundreds to thousands of unique clotting, or thrombotic, events. Using microfluidics, thrombotic events can be studied on defined surfaces of biopolymers, matrix proteins, and tissue factor, under constant flow rate or constant pressure drop conditions. Distinct shear rates can be generated on a device using a single perfusion pump. Microfluidics facilitated both the determination of intraluminal thrombus permeability and the discovery that platelet contractility can be activated by a sudden decrease in flow. Microfluidic devices are ideal for multicolor imaging of platelets, fibrin, and phosphatidylserine and provide a human blood analog to mouse injury models. Overall, microfluidic advances offer many opportunities for research, drug testing under relevant hemodynamic conditions, and clinical diagnostics.
Macroeconomic Analysis Without the Rational Expectations Hypothesis
Authors: Woodford Michael
Published: May 2013

The article presents a temporary equilibrium framework for macroeconomic analysis that allows for a wide range of possible specifications of expectations but reduces to a standard new Keynesian model in the limiting case of rational expectations. This common framework is then used to contrast the assumptions and implications of several different ways of relaxing the assumption of rational expectations. As an illustration of the method, the implications of alternative assumptions for the selection of a monetary policy rule are discussed. Other issues treated include the conditions required for Ricardian equivalence and for existence of a deflation trap.
Econometric Analysis of Games with Multiple Equilibria
Authors: de Paula Áureo
Published: May 2013

This article reviews the recent literature on the econometric analysis of games in which multiple solutions are possible. Multiplicity does not necessarily preclude the estimation of a particular model (and, in certain cases, even improves its identification), but ignoring it can lead to misspecifications. The review starts with a general characterization of structural models that highlights how multiplicity affects the classical paradigm. Because the information structure is an important guide to identification and estimation strategies, I discuss games of complete and incomplete information separately. Although many of the techniques discussed here can be transported across different information environments, some are specific to particular models. Models of social interactions are also surveyed. I close with a brief discussion of postestimation issues and research prospects.
Episodic Neurologic Disorders: Syndromes, Genes, and Mechanisms
Authors: Russell Jonathan F. , Fu Ying-Hui , Ptáček Louis J.
Published: May 2013

Many neurologic diseases cause discrete episodic impairment in contrast with progressive deterioration. The symptoms of these episodic disorders exhibit striking variety. Herein we review what is known of the phenotypes, genetics, and pathophysiology of episodic neurologic disorders. Of these, most are genetically complex, with unknown or polygenic inheritance. In contrast, a fascinating panoply of episodic disorders exhibit Mendelian inheritance. We classify episodic Mendelian disorders according to the primary neuroanatomical location affected: skeletal muscle, cardiac muscle, neuromuscular junction, peripheral nerve, or central nervous system (CNS). Most known Mendelian mutations alter genes that encode membrane-bound ion channels. These mutations cause ion channel dysfunction, which ultimately leads to altered membrane excitability as manifested by episodic disease. Other Mendelian disease genes encode proteins essential for ion channel trafficking or stability. These observations have cemented the channelopathy paradigm, in which episodic disorders are conceptualized as disorders of ion channels. However, we expand on this paradigm to propose that dysfunction at the synaptic and neuronal circuit levels may underlie some episodic neurologic entities.
Nutrient Deficiencies After Gastric Bypass Surgery
Authors: Saltzman Edward , Philip Karl J.
Published: May 2013

Bariatric surgery, and in particular, gastric bypass, is an increasingly utilized and successful approach for long-term treatment of obesity and amelioration of comorbidities. Nutrient deficiencies after surgery are common and have multiple causes. Preoperative factors include obesity, which appears to be associated with risk for several nutrient deficiencies, and preoperative weight loss. Postoperatively, reduced food intake, suboptimal dietary quality, altered digestion and absorption, and nonadherence with supplementation regimens contribute to risk of deficiency. The most common clinically relevant micronutrient deficiencies after gastric bypass include thiamine, vitamin B12, vitamin D, iron, and copper. Reports of deficiencies of many other nutrients, some with severe clinical manifestations, are relatively sporadic. Diet and multivitamin use are unlikely to consistently prevent deficiency, thus supplementation with additional specific nutrients is often needed. Though optimal supplement regimens are not yet defined, most micronutrient deficiencies after gastric bypass currently can be prevented or treated by appropriate supplementation.
Environmental Macroeconomics: Environmental Policy, Business Cycles, and Directed Technical Change
Authors: Fischer Carolyn , Heutel Garth
Published: May 2013

Environmental economics has traditionally fallen in the domain of microeconomics, but approaches from macroeconomics have recently been applied to studying environmental policy. We focus on two macroeconomic tools and their application to environmental economics. First, real-business-cycle models can incorporate pollution and pollution policy and can be used to answer several questions. For example, how should environmental policy adjust to business cycles? How do different types of policies fare in a context with business cycles? Second, endogenous technological growth is an important component of environmental policy. Several studies ask how policy can be designed both to tackle emissions directly and to influence the adoption of clean technologies. We focus on these two aspects of environmental macroeconomics but emphasize that there are many other potential applications.
The Late Paleozoic Ice Age: An Evolving Paradigm
Authors: Montañez Isabel P. , Poulsen Christopher J.
Published: May 2013

The late Paleozoic icehouse was the longest-lived ice age of the Phanerozoic, and its demise constitutes the only recorded turnover to a greenhouse state. This review summarizes evidence for the timing, extent, and behavior of continental ice on Pangea in addition to the climate and ecosystem response to repeated transitions between glacial and interglacial conditions. Combined empirical and climate modeling studies argue for a dynamic ice age characterized by discrete periods of glaciation separated by periods of ice contraction during intermittent warmings, moderate-size ice sheets emanating from multiple ice centers throughout southern Gondwana, possible glaciation of the Northern Hemisphere, and atmospheric CO2 as a primary driver of both ice sheet and climate variability. The glacioeustatic response to fluctuations of these smaller ice sheets was likely less extreme than previously suggested. Modeling studies, stratigraphic relationships, and changes in both the geographic patterns and community compositions of marine fauna and terrestrial flora indicate the potential for strong responses to high-latitude glacial conditions in both ocean circulation and low-latitude climate. The forcings and feedbacks of these linkages, as well as existing climate paradoxes, define research targets for future studies of the late Paleozoic.
(Invited) Fast and Slow Light-Emitting Silicon-Germanium Nanostructures
Authors: Lockwood David J. , Wu Xiaohua , Baribeau Jean-Marc , Mala Selina A. , Modi Nikhil , Tsybeskov Leonid
Published: May 2013

Epitaxially-grown three-dimensional Si/SiGe nanostructures (NSs) produce photoluminescence (PL) and electroluminescence in the desired spectral range of 1.3-1.6 μm. We show that by controlling and modifying such Ge-rich SiGe nanoclusters during growth it is possible to fabricate very fast (PL lifetime <20 ns) and hence more efficient SiGe light-emitting devices. The results presented here demonstrate that in such Si/SiGe 3D NSs with a nominal Ge concentration approaching ~35% the PL peaked near 0.78 eV strongly depends on the Si/SiGe heterointerface abruptness. In other Si/SiGe NS/quantum-well samples with a Ge concentration approaching ~40%, we find two PL bands peaked at ~0.8 eV and ~0.9 eV at low temperatures. The PL peaked at 0.8 eV rises and decays slowly, and it quickly saturates as the excitation intensity increases. In contrast, the PL peaked at 0.9 eV shows a much shorter lifetime and exhibits a linear dependence versus excitation intensity. The slow/delayed PL at 0.8 eV is attributed to carrier recombination at the SiGe NS/Si transition layer while the faster and more efficient PL at 0.9 eV is associated with SiGe quantum wells. More complicated and similarly fast (~10-7 s) decays are observed at very high excitation intensities due to electron-hole droplet formation. The physics of carrier recombination in these Si/SiGe NSs is discussed.
(Invited) Optical and Magnetic Properties of Defective MgO Microcrystals
Authors: Uchino Takashi
Published: May 2013

Micrometer-sized MgO crystals are prepared by solid phase reaction between Mg and B2O3. The MgO microcrystals exhibit efficient photoluminescence (PL) emissions derived from oxygen vacancies, showing broadband laser emission at room temperature. Also, room temperature ferromagnetism is observed in the lasing MgO microcrystals. Ferromagnetic coupling between the surface magnesium vacancies via the surface low-coordinated oxygen atoms is suggested to explain the observed magnetic behavior.
(Invited) Ultraviolet and Long-Lived Blue Luminescence of Oxidized Porous Silicon
Authors: Gelloz Bernard , Mentek Romain , Koshida Nobuyoshi
Published: May 2013

Heavily oxidized porous silicon exhibits a strong blue light emission band including a long-lived phosphorescence component, particularly strong below 200 K, and which was modeled as the result of recombinations from triplet states to ground levels. Its origin is related to molecular species in the silicon/silicon oxide nanostructure. A new emission band, in the ultraviolet (UV) region, has been identified in this material. This UV band is associated to a very narrow absorption band, with a very small Stokes shift. The energy levels involved in its emission mechanism are correlated to those involved in the excitation of the blue emission. Moreover, the effect of exposure to water, pentane and ethanol on the luminescence was studied. The blue band was partially quenched, whereas the UV band was dramatically enhanced by exposure to ethanol. This phenomenon was attributed to a rise in the number of hydroxyl groups after ethanol exposure.
Controlling Actively Q-Switched Laser Output by Nonlinear State Feedback
Authors: Thitsa Makhin , Gray William Steven
Published: May 2013

A powerful nonlinear controlmethodology known as feedback linearization is appliedin order to enhance the performance of Q-switched lasers. Specifically, anactively Q-switched laser system is described, where the desired output pulse shape is generated by nonlinear state feedback control. Open-loop performance is compared with closed-loop performance. After feedback is applied the system can still produce the desired output response even if the pump power is reduced or increased by a factor of two. Excellent approximation of the desired output profile can also be obtained with a 30% fluctuation in the stimulated emission cross section.
Elimination of Curvature in Microelectromechanical-System Membrane
Authors: Sakata Tomomi , Yamaguchi Keita , Nemoto Naru , Usui Mitsuo , Sassa Fumihiro , Ono Kazuyoshi , Takagahara Kazuhiko , Kuwabara Kei , Kodate Junichi , Jin Yoshito
Published: May 2013

This paper describes the correlation between microelectromechanical-system (MEMS) membrane curvature and implanted argon in a microelectromechanical-system membrane. When a free-standing silicon membrane, fabricated through ashing of an organic film, is cleaned by exposure to argon plasma to remove the oxidized surface, the membrane is curved uniformly. The curvature is released by annealing. Total-reflection X-ray fluorescence analysis before/after annealing reveals that argon, which is implanted into the crystal lattice of silicon by argon plasma exposure, is desorbed by annealing. This analysis also indicates that there is a linear correlation between the curvature change and implanted argon.
Impact of Dynamic Body Floating effect on Low-Energy Operation of XCT-SOI CMOS Devices with Aim of Sub-20-nm Regime
Authors: Ino Daishi , Omura Yasuhisa , Sato Daiki
Published: May 2013

This paper considers the dynamic and standby power dissipation characteristics of the scaled XCT-SOI MOSFET. Here, first, we analyze the low-energy operation of XCT-SOI CMOS circuits; the model proposed here strongly suggests that the ‘source potential floating effect (SPFE)’ substantially reduces the operation power consumption. Great advantages of the design methodology are also elucidated. In addition, this study addresses the reality of sub-20-nm-long gate XCT devices and a scaling scheme to suppress the standby power consumption for future low-energy applications.
Tunnel FETs for Mixed-Signal System-On-Chip Applications
Authors: Mallik Abhijit
Published: May 2013

A Tunnel FET (TFET), for which the device operation is based upon a band-to-band tunneling mechanism, is known to be very promising for low-power logic applications. A good output current saturation is necessary to make a device also attractive for mixed-signal system-on-chip applications. In this paper, the output current saturation mechanism for a TFET is reviewed. A comparison of different analog performance parameters between a double-gate (DG) n-channel TFET and a similar DG n-channel MOSFET is presented. It is shown that a TFET can produce higher gain at the same power level than a MOSFET. It is also shown that a complementary TFET amplifier can have more than one order of magnitude higher voltage gain than its MOS counterpart
Dopant-Free CMOS on SOI: Multi-Gate Si-Nanowire Transistors for Logic and Memory Applications
Authors: Schwalke Udo , Krauss Tillmann , Wessely Frank
Published: May 2013

In CMOS technology, NMOS- and PMOS-FETs are hardware defined by choosing the appropriate doping of source (S) and drain (D) junctions with respect to the substrate. However, in this work we report on a novel CMOS multi-gate (MG) nanowire field-effect transistor (NWFET) architecture on silicon-on-insulator (SOI) material which is virtually free of doping. The fabricated MG-NWFETs are originally ambipolar nanowire devices with midgap Schottky-barriers serving as S/D contacts. A tri-gate structure is used as front-gate for current control across the NWFET whereas a planar back-gate is used to select the desired unipolar device type (i.e. NMOS or PMOS) via field-induced accumulation of electrons or holes, respectively. Both, logic and memory devices can be realized with the same simple nanowire structure.