bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact ionization in AlxGa1−xAsySb1−y avalanche photodiodes
Authors: Grzesik M. , Donnelly J. , Duerr E. , Manfra M. , Diagne M. , Bailey R. , Turner G. , Goodhue W.
Published: April 2014

Avalanche photodiodes (APDs) have been fabricated in order to determine the impact ionization coefficients of electrons (α) and holes (β) in AlxGa1−xAsySb1−y lattice matched to GaSb for three alloy compositions: (x = 0.40, y = 0.035), (x = 0.55, y = 0.045), and (x = 0. 65, y = 0.054). The impact ionization coefficients were calculated from photomultiplication measurements made on specially designed APDs, which allowed for both pure electron and pure hole injection in the same device. Photo-multiplication measurements were made at temperatures ranging from 77 K to 300 K for all three alloys. A quasi-physical model with an explicit temperature dependence was used to express the impact ionization coefficients as a function of electric-field strength and temperature. For all three alloys, it was found that α < β at any given temperature. In addition, the values of the impact ionization coefficients were found to decrease as the aluminum concentration of the AlGaAsSb alloy was increased. A value between 1.2 and 4.0 was found for β/α, which is dependent on temperature, alloy composition, and electric-field strength.
Flexible radio-frequency single-crystal germanium switch on plastic substrates
Authors: Qin Guoxuan , Cai Tianhao , Yuan Hao-Chih , Seo Jung-Hun , Ma Jianguo , Ma Zhenqiang
Published: April 2014

This Letter presents the realization and characterizations of the flexible radio-frequency (RF)/microwave switches on plastic substrates employing single-crystal germanium (Ge) nanomembranes. The fabricated flexible Ge single-pole, single-throw (SPST) switches display high frequency responses (e.g., insertion loss of <1.3 dB at up to 30 GHz and isolation >10 dB at up to ∼13 GHz). RF performance tradeoff exists for the flexible Ge switches and the major affecting parameters are determined. The flexible Ge SPST switch shows better RF property to that of the flexible Si SPST switch. Underlying mechanism is investigated by theoretical analysis and modeling of switches with different structures.
Endotaxially stabilized B2-FeSi nanodots in Si (100) via ion beam co-sputtering
Authors: Cassidy Cathal , Kioseoglou Joseph , Singh Vidyadhar , Grammatikopoulos Panagiotis , Lal Chhagan , Sowwan Mukhles
Published: April 2014

We report on the formation of embedded B2-FeSi nanodots in [100]-oriented Si substrates, and investigate the crystallographic mechanism underlying the stabilization of this uncommon, bulk-unstable, phase. The nanodots were approximately 10 nm in size, and were formed by iron thin film deposition and subsequent annealing. Cross-sectional transmission electron microscopy, energy loss spectroscopy mapping, and quantitative image simulation and analysis were utilized to identify the phase, strain, and orientational relationship of the nanodots to the host silicon lattice. X-ray photoelectron spectroscopy was utilized to analyze the surface composition and local bonding. Elasticity calculations yielded a nanodot residual strain value of −18%. Geometrical phase analysis graphically pinpointed the positions of misfit dislocations, and clearly showed the presence of pinned (11¯1¯)Si//(100)FeSi, and unpinned (2¯42)Si//(010)FeSi, interfaces. This partial endotaxy in the host silicon lattice was the mechanism that stabilized the B2-FeSi phase.
Structural evolution and photoluminescence of annealed Si-rich nitride with Si quantum dots prepared by plasma enhanced chemical vapor deposition
Authors: Zeng Xiangbin , Liao Wugang , Wen Guozhi , Wen Xixing , Zheng Wenjun
Published: April 2014

Silicon-rich nitride films were deposited by plasma enhanced chemical vapor deposition. Silicon quantum dots (Si QDs) were formed by post-thermal annealing processing verified using the High-Resolution Transmission Electron Microscope. The 1100 °C thermal annealing leads to the nucleation of silicon atoms, the growth of Si QDs, and the rearrangement of Si 2p and N 1s elements. The structural evolution of silicon-rich nitride thin film with post annealing promotes the formation of Si QDs and Si3N4 matrix. We also investigated the effect of the NH3-to-SiH4 ratio R on the photoluminescence (PL) of SiNx with Si QDs. We found that the broad blue luminescence originates from both quantum confined effect and radiative defects. The intensity of the PL was changed by adjusting the NH3 flow rate. The increase of R could limit the transformation of Si QDs from amorphous to crystalline status, meanwhile lead to the alteration of distribution of defect states. These can help to understand the annealing-dependent characteristics, the PL mechanisms of silicon-rich nitride and to optimize the fabrication process of Si QDs embedded in nitride.
Electron spin magnetism of zigzag graphene nanoribbon edge states
Authors: Xu Kun , Ye Peide D.
Published: April 2014

The electron spin states of zigzag graphene nanoribbon (ZGNR) edge play a pivotal role in the applications of graphene nanoribbons. However, the exact arrangements of the electron spins remain unclear to date. In this report, the electronic spin states of the ZGNR edge have been elucidated through a combination of quantum chemical investigation and previous electron spin resonance experiment observations. An alternating α and β spin configuration of the unpaired electrons along the ZGNR edge is established in ambient condition without any external magnetic field, and the origin of the spin magnetism of the ZGNR edge is revealed. It paves a pathway for the understanding and design of graphene based electronic and spintronic devices.
Reduction phases of thin iron-oxide nanowires upon thermal treatment and Li exposure
Authors: Angelucci Marco , Frau Eleonora , Hassoun Jusef , Hong Inchul , Grazia Betti Maria , Panero Stefania , Scrosati Bruno , Mariani Carlo
Published: April 2014

Iron oxide nanostructures, a promising alternative to carbon-based anode in lithium-ion batteries, can be produced using a hard template route. This procedure guarantees the formation of Fe2O3 nanowires with comparable diameter and size (average diameter 8 nm) with a dominant cubic γ-phase at the surface. Lithium exposure of the iron oxide nanowires in ultra-high-vacuum (UHV) conditions induces reduction of the Fe ion, leading to a Fe3O4 and then to a Fe2+ phase, as determined by means of core-level photoemission spectroscopy. Mild annealing of Fe2O3 in UHV determines an oxygen content reduction for the nanowires at lower temperature with respect to the bulk phase. The morphology and the evolution of the electronic properties upon reduction have been compared to those of micro-sized bulk-like grains, to unravel the role of the reduced size and surface-volume ratio.
Structural and electronic characterization of 355 nm laser-crystallized silicon: Interplay of film thickness and laser fluence
Authors: Semler Matthew R. , Hoey Justin M. , Guruvenket Srinivasan , Gette Cody R. , Swenson Orven F. , Hobbie Erik K.
Published: April 2014

We present a detailed study of the laser crystallization of amorphous silicon thin films as a function of laser fluence and film thickness. Silicon films grown through plasma-enhanced chemical vapor deposition were subjected to a Q-switched, diode-pumped solid-state laser operating at 355 nm. The crystallinity, morphology, and optical and electronic properties of the films are characterized through transmission and reflectance spectroscopy, resistivity measurements, Raman spectroscopy, X-ray diffraction, atomic force microscopy, and optical and scanning-electron microscopy. Our results reveal a unique surface morphology that strongly couples to the electronic characteristics of the films, with a minimum laser fluence at which the film properties are optimized. A simple scaling model is used to relate film morphology to conductivity in the laser-processed films.
Heliostat image drift behavior for different error sources
Authors: Escobar-Toledo Martha , Arancibia-Bulnes Camilo A. , Iriarte-Cornejo Cuitlahuac , Waissman Julio , Riveros-Rosas David , Cabanillas Rafael E. , Estrada Claudio A.
Published: April 2014

Drift is ubiquitous in heliostat fields, and may be caused by diverse geometrical inaccuracies during heliostat installation and operation. This phenomenon is studied for three important primary errors in the present paper: Angular offset in the drive mechanism, pedestal tilt, and canting error. Each error produces characteristic signatures, but there is a diversity of behavior depending on the error parameters and location of the heliostat. The variation of the extent of drift curves is studied as a function of distance, for fixed error parameters. It is found that, in general, this extent is not proportional to distance, except for far heliostats, and depends on a complicated manner on the different parameters involved. Moreover, even though the extent of drift curves becomes proportional to distance for far heliostats, the convergence is very slow, and very variable with the error parameters.
Effects of thermal annealing process on the electrical properties of p+-Si/n-SiC heterojunctions
Authors: Liang J. , Nishida S. , Arai M. , Shigekawa N.
Published: April 2014

The effects of thermal annealing process on the interface in p+-Si/n-SiC heterojunctions fabricated by using surface-activated bonding are investigated. It is found by measuring their current-voltage (I-V) characteristics that the reverse-bias current and the ideality factor decreased to 2.98 × 10−6 mA/cm2 and 1.03, respectively, by annealing the junctions at 1000 °C. Observation by using transmission electron microscopy indicates that an amorphous layer with a thickness of ∼6 nm is formed at the unannealed interface, which vanishes after annealing at 1000 °C. No structural defects at the interface are observed even after annealing at such a high temperature.
High-performance broadband optical coatings on InGaN/GaN solar cells for multijunction device integration
Authors: Young N. G. , Perl E. E. , Farrell R. M. , Iza M. , Keller S. , Bowers J. E. , Nakamura S. , DenBaars S. P. , Speck J. S.
Published: April 2014

We demonstrate InGaN/GaN multiple quantum well solar cells grown by metalorganic chemical vapor deposition on a bulk (0001) substrate with high-performance broadband optical coatings to improve light absorption. A front-side anti-reflective coating and a back-side dichroic mirror were designed to minimize front surface reflections across a broad spectral range and maximize rear surface reflections only in the spectral range absorbed by the InGaN, making the cells suitable for multijunction solar cell integration. Application of optical coatings increased the peak external quantum efficiency by 56% (relative) and conversion efficiency by 37.5% (relative) under 1 sun AM0 equivalent illumination.
Persistence of uranium emission in laser-produced plasmas
Authors: LaHaye N. L. , Harilal S. S. , Diwakar P. K. , Hassanein A.
Published: April 2014

Detection of uranium and other nuclear materials is of the utmost importance for nuclear safeguards and security. Optical emission spectroscopy of laser-ablated U plasmas has been presented as a stand-off, portable analytical method that can yield accurate qualitative and quantitative elemental analysis of a variety of samples. In this study, optimal laser ablation and ambient conditions are explored, as well as the spatio-temporal evolution of the plasma for spectral analysis of excited U species in a glass matrix. Various Ar pressures were explored to investigate the role that plasma collisional effects and confinement have on spectral line emission enhancement and persistence. The plasma-ambient gas interaction was also investigated using spatially resolved spectra and optical time-of-flight measurements. The results indicate that ambient conditions play a very important role in spectral emission intensity as well as the persistence of excited neutral U emission lines, influencing the appropriate spectral acquisition conditions.
Silver antimony Ohmic contacts to moderately doped n-type germanium
Authors: Dumas D. C. S. , Gallacher K. , Millar R. , MacLaren I. , Myronov M. , Leadley D. R. , Paul D. J.
Published: April 2014

A self doping contact consisting of a silver/antimony alloy that produces an Ohmic contact to moderately doped n-type germanium (doped to a factor of four above the metal-insulator transition) has been investigated. An evaporation of a mixed alloy of Ag/Sb (99%/1%) onto n-Ge (ND=1×1018 cm−3) annealed at 400 °C produces an Ohmic contact with a measured specific contact resistivity of (1.1±0.2)×10−5 Ω-cm2. It is proposed that the Ohmic behaviour arises from an increased doping concentration at the Ge surface due to the preferential evaporation of Sb confirmed by transmission electron microscope analysis. It is suggested that the doping concentration has increased to a level where field emission will be the dominate conduction mechanism. This was deduced from the low temperature electrical characterisation of the contact, which exhibits Ohmic behaviour down to a temperature of 6.5 K.
Straintronics-based magnetic tunneling junction: Dynamic and static behavior analysis and material investigation
Authors: Barangi Mahmood , Mazumder Pinaki
Published: April 2014

We theoretically study the dynamic and static effects of mechanical stress on a straintronics device that includes a piezoelectric film combined with a magnetic tunneling junction. The inverse magnetostriction effect is studied in detail by realizing the varying magnetic susceptibility of the nanomagnet under stress. A dynamic model is developed based on the Landau-Lifshitz-Gilbert (LLG) equation, which provides a platform to simulate the magnetization vector's behavior, critical flipping voltage, and delay properties. Furthermore, by converting the LLG equation into a 2nd order damping differential equation, we develop a proximate approach. This approach predicts the dynamic behavior of the magnetization vector and its dependency on material properties and applied voltage across the device without using sophisticated numerical calculations of the LLG model. Different dynamic and static material properties are observed by simulating five common magnetostrictive materials, including a newly discovered alloy, Galfenol.
Analytical determination of the constitutive behavior from micro-pillar testing: Application to a tempered martensitic steel
Authors: Ilchuk N. , Spätig P. , Seifert H.-P.
Published: April 2014

Micro-compression experiments were carried out on micro-pillars, with nominal diameter of 10 μm and height 20 μm, and fabricated from a high-chromium tempered martensitic steels developed for nuclear applications. An analytical method was proposed to calculate the imposed compressive displacement on the pillar that allows determining the constitutive behavior up to about 5% of plastic strain. The experimental micro-compression curves were showed to be adequately modeled by the finite element simulations, which were used to validate the main assumption considered for the analytical model development.
Plasma-enhanced chemical vapor deposition of graphene on copper substrates
Authors: Woehrl Nicolas , Ochedowski Oliver , Gottlieb Steven , Shibasaki Kosuke , Schulz Stephan
Published: April 2014

A plasma enhanced vapor deposition process is used to synthesize graphene from a hydrogen/methane gas mixture on copper samples. The graphene samples were transferred onto SiO2 substrates and characterized by Raman spectroscopic mapping and atomic force microscope topographical mapping. Analysis of the Raman bands shows that the deposited graphene is clearly SLG and that the sheets are deposited on large areas of several mm2. The defect density in the graphene sheets is calculated using Raman measurements and the influence of the process pressure on the defect density is measured. Furthermore the origin of these defects is discussed with respect to the process parameters and hence the plasma environment.
Visualizing the photovoltaic behavior of a type-II p-n heterojunction superstructure
Authors: Xing Juanjuan , Takeguchi Masaki , Hashimoto Ayako , Cao Junyu , Ye Jinhua
Published: April 2014

Photovoltaic behavior of a CaFe2O4/ZnFe2O4 p-n multi-junction was investigated with electron holography combined with an in situ light irradiation system. Potential profiles of the samples with and without light irradiation were extracted to measure the open circuit photovoltage generated either by the whole heterojunction superstructure or from each p-n junction. Investigation on the variation in the energy band configuration under light irradiation revealed the mechanism involved in the photoelectric effect, with respect to the properties of the heterojunction and its periodic quantum structure.
Multiplexed DNA repair assays for multiple lesions and multiple doses via transcription inhibition and transcriptional mutagenesis
Authors: Nagel Zachary D. , Margulies Carrie M. , Chaim Isaac A. , McRee Siobhan K. , Mazzucato Patrizia , Ahmad Anwaar , Abo Ryan P. , Butty Vincent L. , Forget Anthony L. , Samson Leona D.
Published: April 2014

Significance

DNA, the blueprint of the cell, is constantly damaged by chemicals and radiation. Because DNA damage may cause cell death or mutations that may lead to diseases such as cancer, cells are armed with an arsenal of several distinct mechanisms for repairing the many types of DNA damage that occur. DNA repair capacity (DRC) varies among individuals, and reduced DRC is associated with disease risk; however, the available DRC assays are labor intensive and measure only one pathway at a time. Herein, we present powerful new assays that measure DRC in multiple pathways in a single assay. We use the assays to measure interindividual DRC differences and inhibition of DNA repair, and to uncover unexpected error-prone transcriptional bypass of a thymine dimer.
Two-photon imaging of Zn
2+
dynamics in mossy fiber boutons of adult hippocampal slices
Authors: Khan Mustafa , Goldsmith Christian R. , Huang Zhen , Georgiou John , Luyben Thomas T. , Roder John C. , Lippard Stephen J. , Okamoto Kenichi
Published: April 2014

Significance

Zinc is essential to various organs, including the liver and brain. In the brain, Zn
2+
is present at high concentrations and selectively accumulates in the presynaptic vesicles of glutamatergic neurons. Understanding the roles of zinc in these glutamatergic vesicles has been hampered by the inability to visualize zinc accumulation and release at individual synapses. We report a fluorescent zinc-responsive probe and a technique to selectively image mobile zinc in presynaptic vesicles. Using two-photon laser microscopy, we visualized Zn
2+
at the synaptic level in tissues from adult mouse brains and successfully monitored Zn
2+
release from individual neurons. Our probe and methodology will allow further studies into how Zn
2+
regulates synaptic plasticity and other neurologic functions.
Constraining factors on the family of resultative constructions
Authors: Luzondo Oyón Alba
Published: April 2014

Drawing on the assumptions made in Construction Grammar(s), the present proposal addresses the debate between formulating broad-scale generalizations of the type postulated by Goldberg (1995) or finer-grained analyses, heavily based on lexical-class identification, as those put forward by Boas (2010, 2011), who claims that Goldberg’s account leads to the over-generation of ungrammatical examples. The position taken here is that, although Goldberg’s theory has largely overlooked the role of verb meaning(s), generalizations in the form of constraints are still necessary to build a fully principled account of lexical-constructional fusion. Taking the family of resultative constructions as a case study, I employ the analytical tools (i.e. the apparatus of so-called internal and external constraints on constructional integration) developed by the Lexical Constructional Model in order to show that a fine-nuanced description can go hand in hand with the postulation of macro-generalizations.
A constructional approach to transitional formatives
Authors: Portero Muñoz Carmen
Published: April 2014

The noun head is commonly found in the second position of many English noun compounds. Typically, noun compounds with head in the right are endocentric formations, that is, composite forms which designate a more specific type of the concept denoted by head (e.g. pinhead). The noun head is also found in a significant number of so called ‘exocentric’ formations with a variety of interconnected meanings (e.g. airhead, acidhead, Potterhead). The different exocentric patterns where head participates raise questions about the grammatical status of this element, which is sometimes analysed as a suffixal element, illustrating the fuzzy boundaries between derivation and compounding. In the linguistic literature there is an extensive debate as to whether processes like this one are to be regarded as cases of grammaticalization or lexicalisation. In this paper it will be proposed that exocentric formations in -head are suitable for an analysis using a schema-based approach in Ryder’s (1994) fashion, or a constructional approach (Booij, 2010a) insofar as new creations arise by analogy with the patterns that can be extracted from existing cases. The different patterns of exocentric formations with head can be conveniently characterized by postulating a hierarchical lexicon with schemas or constructions of different degree of abstraction.
Phenolic compounds from leaves of Casimiroa edulis showed adipogenesis activity
Authors: Nagai Hiroyuki , Tanaka Toshiyuki , Goto Tsuyoshi , Kusudo Tatsuya , Takahashi Nobuyuki , Kawada Teruo
Published: April 2014

Casimiroa edulis is known as cochitzapotl, and it belongs to a species of tropical fruiting tree in the family Rutaceae, native to eastern Mexico and Central America south to Costa Rica. In this study, we isolated two furocoumarins and two polymethoxyflavones from leaves of C. edulis and evaluated the functions of glucose and lipid metabolism activity with 3T3-L1 adipocytes. We discovered that the addition of furocoumarins increased glucose uptake and lipid accumulation in 3T3-L1 adipocyte. These results suggest that furocoumarin compounds can be used as functional food-derived compounds, to regulate adipocyte functioning for the management of metabolic syndrome, which is associated with dysfunctions of glucose and lipid metabolism.
Pectin of Prunus domestica L. alters sulfated structure of cell-surface heparan sulfate in differentiated Caco-2 cells through stimulation of heparan sulfate 6-O-endosulfatase-2
Authors: Nishida Mitsutaka , Murata Kazuma , Kanamaru Yoshihiro , Yabe Tomio
Published: April 2014

Although previous reports have suggested that pectin induces morphological changes of the small intestine in vivo, the molecular mechanisms have not been elucidated. As heparan sulfate plays important roles in development of the small intestine, to verify the involvement of heparan sulfate (HS) in the pectin-induced morphological changes of the small intestine, the effects of pectin from Prunus domestica L. on cell-surface HS were investigated using differentiated Caco-2 cells. Disaccharide compositional analysis revealed that sulfated structures of HS were markedly changed by pectin administration. Real-time RT-PCR showed that pectin upregulated human HS 6-O-endosulfatase-2 (HSulf-2) expression and markedly inhibited HSulf-1 expression. Furthermore, inhibition analysis suggested that pretreatment with fibronectin III1C fragment, RGD peptide, and ERK1/2 inhibitor suppressed pectin-induced HSulf-2 expression. These observations indicate that pectin induced the expression of HSulf-2 through the interaction with fibronectin, α5β1 integrin, and ERK1/2, thereby regulating the sulfated structure of HS on differentiated Caco-2 cells.
Does a water‐training macrocycle really create imbalances in swimmers' shoulder rotator muscles?
Authors: Batalha Nuno , Marmeleira José , Garrido Nuno , Silva António J.
Published: April 2014

The continuous execution of swimming techniques may cause muscle imbalances in shoulder rotators leading to injury. However, there is a lack of published research studies on this topic. The aim of this study was to analyze the influence of a competitive swim period on the shoulder rotator–cuff balance in young swimmers. A randomized controlled pretest–posttest design was used, with two measurements performed during the first macrocycle of the swimming season (baseline and 16 weeks). Twenty‐seven young male swimmers (experimental group) and 22 male students who were not involved in swim training (control group) with the same characteristics were evaluated. Peak torque of shoulder internal and external rotators was assessed. Concentric action at 1.04 rad s−1 (3 repetitions) and 3.14 rad s−1 (20 repetitions) was measured using an isokinetic dynamometer (Biodex System 3). External/internal rotators strength ratios were also obtained. For both protocols, there were significant training effects on internal rotator strength and external/internal rotator ratios (p ≤. 05). This trend was the same for both shoulders. Within‐group analysis showed significant changes from baseline to 16 weeks for internal rotators strength and unilateral ratios of the experimental group. Swimmers' internal rotator strength levels increased significantly. In contrast, a significant decrease of the unilateral ratios was observed. Findings suggest that a competitive swim macrocycle leads to an increase in muscular imbalances in the shoulder rotators of young competitive swimmers. Swimming coaches should consider implementing a compensatory strength‐training program.
Repair of Congenital Heart Disease with Associated Pulmonary Hypertension in Children: What are the Minimal Investigative Procedures? Consensus Statement from the Congenital Heart Disease and Pediatric Task Forces, Pulmonary Vascular Research Institute (PVRI)
Authors: Lopes Antonio Augusto , Barst Robyn J. , Haworth Sheila Glennis , Rabinovitch Marlene , Dabbagh Maha Al , del Cerro Maria Jesus , Ivy Dunbar , Kashour Tarek , Kumar Krishna , Harikrishnan S. , D'Alto Michele , Thomaz Ana Maria , Zorzanelli Leína , Aiello Vera D. , Mocumbi Ana Olga , Santana Maria Virginia T. , Galal Ahmed Nasser , Banjar Hanaa , Tamimi Omar , Heath Alexandra , Flores Patricia C. , Diaz Gabriel , Sandoval Julio , Kothari Shyam , Moledina Shahin , Gonçalves Rilvani C. , Barreto Alessandra C. , Binotto Maria Angélica , Maia Margarida , Habshan Fahad Al , Adatia Ian
Published: April 2014

Standardization of the diagnostic routine for children with congenital heart disease associated with pulmonary arterial hypertension (PAH‐CHD) is crucial, in particular since inappropriate assignment to repair of the cardiac lesions (e.g., surgical repair in patients with elevated pulmonary vascular resistance) may be detrimental and associated with poor outcomes. Thus, members of the Congenital Heart Disease and Pediatric Task Forces of the Pulmonary Vascular Research Institute decided to conduct a survey aimed at collecting expert opinion from different institutions in several countries, covering many aspects of the management of PAH‐CHD, from clinical recognition to noninvasive and invasive diagnostic procedures and immediate postoperative support. In privileged communities, the vast majority of children with congenital cardiac shunts are now treated early in life, on the basis of noninvasive diagnostic evaluation, and have an uneventful postoperative course, with no residual PAH. However, a small percentage of patients (older at presentation, with extracardiac syndromes or absence of clinical features of increased pulmonary blood flow, thus suggesting elevated pulmonary vascular resistance) remain at a higher risk of complications and unfavorable outcomes. These patients need a more sophisticated diagnostic approach, including invasive procedures. The authors emphasize that decision making regarding operability is based not only on cardiac catheterization data but also on the complete diagnostic picture, which includes the clinical history, physical examination, and all aspects of noninvasive evaluation.
Andrew Johnson and the Legacy of the Civil War
Authors: Varon Elizabeth R.
Published: April 2014

Perhaps no other American leader has experienced so precipitous a fall from grace as Andrew Johnson, seventeenth president of the United States (1865–1869). During the Civil War, Johnson was the preeminent symbol of Southern Unionism—and thus, the ideal running mate for Abraham Lincoln in the 1864 election, on the Union Party ticket. Four years later, as president, he was widely viewed as a traitor to his political allies and even to the Union, and barely escaped impeachment. In modern scholarship, the image persists of Johnson as politically inept, and willfully self-destructive—driven by visceral emotions, particularly by implacable racism, and lacking in Lincoln’s skill for reading and molding public opinion. But such an image fails to capture fully the scope of his political influence. As President, Johnson staked claims that shaped the course of Reconstruction—that emancipation signified nothing but freedom; that the immediate aftermath of the Civil War was a golden moment of reconciliation, which Radicals squandered by pushing for black suffrage; that the Congressional program of Reconstruction inaugurated a period of so-called “black rule,” during which former Confederates were victimized and disfranchised. Such propaganda was designed to deem the Republican experiment in black citizenship a failure before it even began. Johnson’s term offers an example as striking as any in U.S. history of the power of presidents to set the terms of political debates—and of the power of their words to do lasting harm.
Federal Indian Law
Authors: Duthu N. Bruce
Published: April 2014

United States law recognizes American Indian tribes as distinct political bodies with powers of self-government. Their status as sovereign entities predates the formation of the United States and they are enumerated in the U.S. Constitution as among the subjects (along with foreign nations and the several states) with whom Congress may engage in formal relations. And yet, despite this long-standing recognition, federal Indian law remains curiously ambivalent, even conflicted, about the legal and political status of Indian tribes within the U.S. constitutional structure. On the one hand, tribes are recognized as sovereign bodies with powers of self-government within their lands. On the other, long-standing precedents of the Supreme Court maintain that Congress possesses plenary power over Indian tribes, with authority to modify or even eliminate their powers of self-government. These two propositions are in tension with one another and are at the root of the challenges faced by political leaders and academics alike in trying to understand and accommodate the tribal rights to self-government. The body of laws that make up the field of federal Indian law include select provisions of the U.S. Constitution (notably the so-called Indian Commerce Clause), treaties between the United States and various Indian tribes, congressional statutes, executive orders, regulations, and a complex and rich body of court decisions dating back to the nation’s formative years. The noted legal scholar Felix Cohen brought much-needed coherence and order to this legal landscape in the 1940s when he led a team of scholars within the Office of the Solicitor in the Department of the Interior to produce a handbook on federal Indian law. The revised edition of Cohen’s Handbook of Federal Indian Law is still regarded as the seminal treatise in the field. Critically, however, this rich body of law only hints at the real story in federal Indian law. The laws themselves serve as historical and moral markers in the ongoing clash between indigenous and nonindigenous societies and cultures still seeking to establish systems of peaceful coexistence in shared territories. It is a story about the limits of legal pluralism and the willingness of a dominant society and nation to acknowledge and honor its promises to the first inhabitants and first sovereigns.
Vietnamese Americans in Little Saigon, California
Authors: Nguyen Phuong
Published: April 2014

Little Saigon is the preferred name of Vietnamese refugee communities throughout the world. This article focuses primarily on the largest such community, in Orange County, California. This suburban ethnic enclave is home to the largest concentration of overseas Vietnamese, nearly 200,000, or 10 percent of the Vietnamese American population. Because of its size, location, and demographics, Little Saigon is also home to some of the most influential intellectuals, entertainers, businesspeople, and politicians in the Vietnamese diaspora, many of whom are invested in constructing Little Saigon as a transnational oppositional party to the government of Vietnam. Unlike traditional immigrant ethnic enclaves, Little Saigon is a refugee community whose formation and development emerged in large part from America’s efforts to atone for its epic defeat in Vietnam by at least sparing some of its wartime allies a life under communism. Much of Little Saigon’s cultural politics revolve around this narrative of rescue, although the number guilt-ridden Americans grows smaller and more conservative, while the loyalists of the pre-1975 Saigon regime struggle to instill in the younger generation of Vietnamese an appreciation of their refugee roots.
Native Americans and Cities
Authors: Rosenthal Nicolas G.
Published: April 2014

An important relationship has existed between Native Americans and cities from pre-Columbian times to the early 21st century. Long before Europeans arrived in the Americas, indigenous peoples developed societies characterized by dense populations, large-scale agriculture, monumental architecture, and complex social hierarchies. Following European and American conquest and colonization, Native Americans played a crucial role in the development of towns and cities throughout North America, often on the site of former indigenous settlements.

Beginning in the early 20th century, Native Americans began migrating from reservations to U.S. cities in large numbers and formed new intertribal communities. By 1970, the majority of the Native American population lived in cities and the numbers of urban American Indians have been growing ever since. Indian Country in the early 21st century continues to be influenced by the complex and evolving ties between Native Americans and cities.
Religion in African American History
Authors: Weisenfeld Judith
Published: April 2014

Dynamic and creative exchanges among different religions, including indigenous traditions, Protestant and Catholic Christianity, and Islam, all with developing theologies and institutions, fostered substantial collective religious and cultural identities within African American communities in the United States. The New World enslavement of diverse African peoples and the cultural encounter with Europeans and Native Americans produced distinctive religious perspectives that aided individuals and communities in persevering under the dehumanization of slavery and oppression. As African Americans embraced Christianity beginning in the 18th century, especially after 1770, they gathered in independent church communities and created larger denominational structures such as the African Methodist Episcopal Church, the African Methodist Episcopal Zion Church, and the National Baptist Convention. These churches and denominations became significant arenas for spiritual support, educational opportunity, economic development, and political activism. Black religious institutions served as contexts in which African Americans made meaning of the experience of enslavement, interpreted their relationship to Africa, and charted a vision for a collective future. The early 20th century saw the emergence of new religious opportunities as increasing numbers of African Americans turned to Holiness and Pentecostal churches, drawn by the focus on baptism in the Holy Spirit and enthusiastic worship that sometimes involved speaking in tongues. The Great Migration of southern blacks to southern and northern cities fostered the development of a variety of religious options outside of Christianity. Groups such as the Moorish Science Temple and the Nation of Islam, whose leaders taught that Islam was the true religion of people of African descent, and congregations of Ethiopian Hebrews promoting Judaism as the heritage of black people, were founded in this period. Early-20th-century African American religion was also marked by significant cultural developments as ministers, musicians, actors, and other performers turned to new media, such as radio, records, and film, to contribute to religious life. In the post–World War II era, religious contexts supported the emergence of the modern Civil Rights movement. Black religious leaders emerged as prominent spokespeople for the cause and others as vocal critics of the goal of racial integration, as in the case of the Nation of Islam and religious advocates of Black Power. The second half of the 20th century and the early 21st-first century saw new religious diversity as a result of immigration and cultural transformations within African American Christianity with the rise of megachurches and televangelism.
Anna May Wong and Asian American Popular Culture
Authors: Lim Shirley
Published: April 2014

Anna May Wong (January 3, 1905–February 3, 1961) was the first Chinese American movie star and the first Asian American actress to gain international recognition. Wong broke the codes of yellowface in both American and European cinema to become one of the major global actresses of Asian descent between the world wars. She made close to sixty films that circulated around the world and in 1951 starred in her own television show, The Gallery of Madame Liu-Tsong, produced by the defunct Dumont Network. Examining Wong’s career is particularly fruitful because of race’s centrality to the motion pictures’ construction of the modern American nation-state, as well as its significance within the global circulation of moving images.

Born near Los Angeles’s Chinatown, Wong began acting in films at an early age. During the silent era, she starred in films such as The Toll of the Sea (1922), one of the first two-tone Technicolor films, and The Thief of Baghdad (1924). Frustrated by Hollywood roles, Wong left for Europe in the late 1920s, where she starred in several films and plays, including Piccadilly (1929) and A Circle of Chalk (1929) opposite Laurence Olivier. Wong traveled between the United States and Europe for film and stage work. In 1935 she protested Metro-Goldwyn-Mayer’s refusal to consider her for the leading role of O-Lan in the Academy Award–winning film The Good Earth (1937). Wong then paid her one and only visit to China. In the late 1930s, she starred in several B films such as King of Chinatown (1939), graced the cover of the mass-circulating American magazine Look, and traveled to Australia. In 1961, Wong died of Laennec’s cirrhosis, a disease typically stemming from alcoholism. Yet, as her legacy shows, for a brief moment a glamorous Chinese American woman occupied a position of transnational importance.
A power set-based statistical selection procedure to locate susceptible rare variants associated with complex traits with sequencing data
Authors: Sun Hokeun , Wang Shuang
Published: April 2014

Motivation: Existing association methods for rare variants from sequencing data have focused on aggregating variants in a gene or a genetic region because of the fact that analysing individual rare variants is underpowered. However, these existing rare variant detection methods are not able to identify which rare variants in a gene or a genetic region of all variants are associated with the complex diseases or traits. Once phenotypic associations of a gene or a genetic region are identified, the natural next step in the association study with sequencing data is to locate the susceptible rare variants within the gene or the genetic region.

Results: In this article, we propose a power set-based statistical selection procedure that is able to identify the locations of the potentially susceptible rare variants within a disease-related gene or a genetic region. The selection performance of the proposed selection procedure was evaluated through simulation studies, where we demonstrated the feasibility and superior power over several comparable existing methods. In particular, the proposed method is able to handle the mixed effects when both risk and protective variants are present in a gene or a genetic region. The proposed selection procedure was also applied to the sequence data on the ANGPTL gene family from the Dallas Heart Study to identify potentially susceptible rare variants within the trait-related genes.

Availability and implementation: An R package ‘rvsel’ can be downloaded from http://www.columbia.edu/∼sw2206/ and http://statsun.pusan.ac.kr.

Contact: sw2206@columbia.edu

Supplementary information:  Supplementary Data are available at Bioinformatics online.
Seeing the body produces limb-specific modulation of skin temperature
Authors: Sadibolova Renata , Longo Matthew R.
Published: April 2014

Vision of the body, even when non-informative about stimulation, affects somatosensory processing. We investigated whether seeing the body also modulates autonomic control in the periphery by measuring skin temperature while manipulating vision. Using a mirror box, the skin temperature was measured from left hand dorsum while participants: (i) had the illusion of seeing their left hand, (ii) had the illusion of seeing an object at the same location or (iii) looked directly at their contralateral right hand. Skin temperature of the left hand increased when participants had the illusion of directly seeing that hand but not in the other two view conditions. In experiment 2, participants viewed directly their left or right hand, or the box while we recorded both hand dorsum temperatures. Temperature increased in the viewed hand but not the contralateral hand. These results show that seeing the body produces limb-specific modulation of thermal regulation.
Mitigating the squash effect: sloths breathe easily upside down
Authors: Cliffe Rebecca N. , Avey-Arroyo Judy A. , Arroyo Francisco J. , Holton Mark D. , Wilson Rory P.
Published: April 2014

Sloths are mammals renowned for spending a large proportion of time hanging inverted. In this position, the weight of the abdominal contents is expected to act on the lungs and increase the energetic costs of inspiration. Here, we show that three-fingered slothsBradypus variegatuspossess unique fibrinous adhesions that anchor the abdominal organs, particularly the liver and glandular stomach, to the lower ribs. The key locations of these adhesions, close to the diaphragm, prevent the weight of the abdominal contents from acting on the lungs when the sloth is inverted. Using ventilation rate and body orientation data collected from captive and wild sloths, we use an energetics-based model to estimate that these small adhesions could reduce the energy expenditure of a sloth at any time it is fully inverted by almost 13%. Given body angle preferences for individual sloths in our study over time, this equates to mean energy saving of 0.8–1.5% across individuals (with individual values ranging between 0.01 and 8.6%) per day. Given the sloth's reduced metabolic rate compared with other mammals and extremely low energy diet, these seemingly innocuous adhesions are likely to be important in the animal's energy budget and survival.
A semi-automated measurement technique for the assessment of radiolucency
Authors: Pegg E. C. , Kendrick B. J. L. , Pandit H. G. , Gill H. S. , Murray D. W.
Published: April 2014

The assessment of radiolucency around an implant is qualitative, poorly defined and has low agreement between clinicians. Accurate and repeatable assessment of radiolucency is essential to prevent misdiagnosis, minimize cases of unnecessary revision, and to correctly monitor and treat patients at risk of loosening and implant failure. The purpose of this study was to examine whether a semi-automated imaging algorithm could improve repeatability and enable quantitative assessment of radiolucency. Six surgeons assessed 38 radiographs of knees after unicompartmental knee arthroplasty for radiolucency, and results were compared with assessments made by the semi-automated program. Large variation was found between the surgeon results, with total agreement in only 9.4% of zones and a kappa value of 0.602; whereas the automated program had total agreement in 81.6% of zones and a kappa value of 0.802. The software had a ‘fair to excellent’ prediction of the presence or the absence of radiolucency, where the area under the curve of the receiver operating characteristic curves was 0.82 on average. The software predicted radiolucency equally well for cemented and cementless implants (p= 0.996). The identification of radiolucency using an automated method is feasible and these results indicate that it could aid the definition and quantification of radiolucency.
Assessment of the unified analytical solution of the steady-state atmospheric diffusion equation for stable conditions
Authors: Pimentel L. C. G. , Pérez Guerrero J. S. , Ulke A. G. , Duda F. P. , Heilbron Filho P. F. L.
Published: April 2014

In this work, the performance of a unified formal analytical solution for the simulation of atmospheric diffusion problems under stable conditions is evaluated. The eigenquantities required by the formal analytical solution are obtained by solving numerically the associated eigenvalue problem based on a newly developed algorithm capable of being used in high orders and without missing eigenvalues. The performance of the formal analytical solution is evaluated by comparing the converged predicted results against the observed values in the stable runs of the Prairie Grass experiment as well as the simulated results available in the literature. It was found that the developed algorithm was efficient and that the convergence rate depends on the stability condition and the considered parametrizations for wind speed and turbulence. The comparisons among predicted and observed concentrations showed a good agreement and indicate that the considered dispersion formulations are appropriate to simulate dispersion under slightly to moderate atmospheric stable conditions.
From molecular dynamics to Brownian dynamics
Authors: Erban Radek
Published: April 2014

Three coarse-grained molecular dynamics (MD) models are investigated with the aim of developing and analysing multi-scale methods which use MD simulations in parts of the computational domain and (less detailed) Brownian dynamics (BD) simulations in the remainder of the domain. The first MD model is formulated in one spatial dimension. It is based on elastic collisions of heavy molecules (e.g. proteins) with light point particles (e.g. water molecules). Two three-dimensional MD models are then investigated. The obtained results are applied to a simplified model of protein binding to receptors on the cellular membrane. It is shown that modern BD simulators of intracellular processes can be used in the bulk and accurately coupled with a (more detailed) MD model of protein binding which is used close to the membrane.