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Blacksburg, VA, United States

Virginia Polytechnic Institute and State University, popularly known as Virginia Tech, is a public land-grant university with a main campus in Blacksburg, Virginia, educational facilities in six regions statewide, and a study-abroad site in Switzerland. The commonwealth's third-largest university and a leading research institution, Virginia Tech offers 225 undergraduate and graduate degree programs to some 31,000 students and manages a research portfolio of $454 million. The university fulfills its land-grant mission of transforming knowledge to practice through technological leadership and by fueling economic growth and job creation locally, regionally, and across Virginia.The Virginia Tech Board of Visitors serves as the university's governing body. The board comprises 13 members who are appointed by the governor of Virginia. Serving as ex-officio, non-voting representatives are the president of the state Board of Agriculture and Consumer Services; the presidents of the university's faculty senate and staff senate; and an undergraduate student and a graduate student selected through a competitive review process. Wikipedia.

Meng X.-J.,Virginia Polytechnic Institute and State University
Virus Research | Year: 2011

Hepatitis E virus (HEV) is an important but extremely understudied pathogen. The mechanisms of HEV replication and pathogenesis are poorly understood, and a vaccine against HEV is not yet available. HEV is classified in the family Hepeviridae consisting of at least four recognized major genotypes. Genotypes 1 and 2 HEV are restricted to humans and associated with epidemics in developing countries, whereas genotypes 3 and 4 HEV are zoonotic and responsible for sporadic cases worldwide. The identification and characterization of a number of animal strains of HEV from pigs, chickens, rabbits, rats, mongoose, deer, and possibly cattle and sheep have significantly broadened the host range and diversity of HEV. The demonstrated ability of cross-species infection by some animal strains of HEV raises public health concerns for zoonotic HEV infection. Pigs are a recognized reservoir for HEV, and pig handlers are at increased risk of zoonotic HEV infection. Sporadic cases of hepatitis E have been definitively linked to the consumption of raw or undercooked animal meats such as pig livers, sausages, and deer meats. In addition, since large amounts of viruses excreted in feces, animal manure land application and runoffs can contaminate irrigation and drinking water with concomitant contamination of produce or shellfish. HEV RNA of swine origin has been detected in swine manure, sewage water and oysters, and consumption of contaminated shellfish has also been implicated in sporadic cases of hepatitis E. Therefore, the animal strains of HEV pose not only a zoonotic risk but also food and environmental safety concerns. © 2011 Elsevier B.V. Source

Chapman M.C.,Virginia Polytechnic Institute and State University
Bulletin of the Seismological Society of America | Year: 2013

The 23 August 2011 Mw 5.7 Virginia earthquake was studied using local and teleseismic recordings. The earthquake was a shallow reverse rupture in the central Virginia seismic zone. The epicenter was at 37.905° N, 77.975° W, with focal depth 8.0 km. A few local stations recorded both the mainshock and several of the larger aftershocks. This allowed location of the mainshock epicenter relative to the accurate locations of aftershocks recorded by a temporary local deployment of stations. The aftershocks define a planar zone oriented in agreement with the mainshock focal mechanism nodal plane. The mainshock focal depth was determined by comparing teleseismic waveforms with synthetics. Local and teleseismic recordings show evidence of a complex rupture, and were used to locate two large subevents relative to a small initial subevent. The initial slip episode had moment of roughly 2.5 × 1016 N·m, and was followed 0.75 s later by a subevent with a moment of approximately 2.3 × 1017 N·m that amounted to approximately 60% of the total moment release. A third subevent with moment approximately 1.2 × 1017 N·m occurred 1.57 s after rupture initiation. The mainshock rupture occurred at the base of the early aftershock zone. Rupture initiated near the southwestern corner of the aftershock zone and proceeded to the northeast along strike and up-dip. The three subevents may have involved a small fault area: the estimated distance between the initial and final subevent is only 2.0 km. However, the total rise time of the earthquake was comparatively large. The estimated distance between the subevents and the origin time difference between subevents suggests a slow rupture velocity of 1.3-1.7 km=s. This was a consequence of the rupture being comprised of two short-duration energetic slip events that were well separated in time along with a small, possibly low stress-drop, initiation event. Source

Viehland D.D.,Virginia Polytechnic Institute and State University | Salje E.K.H.,University of Cambridge
Advances in Physics | Year: 2014

Domain boundaries typically constitute only a minute fraction of the total volume of a crystal. However, a special (but not unusual) situation can occur in which the domain boundary energy becomes very small. Specifically, the domain size is miniaturized to near-atomic scales and the domain boundary density becomes extremely high. In such cases, the properties of the crystal become dominated by a combination of both the domains and the domain boundaries. This phenomenon differs from most ferromagnetic or ferroelectric materials wherein the motion of the domain boundaries dominates the response. As reported herein, novel emergent phenomena that differ from the properties of either the domains or the domain boundaries may be expected. In this article, we focus on one specific state found in ferroic materials -namely, the adaptive ferroic state. This state can be found, for example, in tweed-like structures in morphotropic phase boundary piezoelectric crystals, ferromagnetic shape memory alloys, and pre-martensitic states. In these materials, the properties of the twin boundaries represent the principal contributors to the functionality of a given system. In fact, further investigations of domain boundary-dominated phenomena could result in novel potential for tailoring functional properties for a desired outcome. It should also be noted that new properties can be designed into twin boundaries that are not the properties of the domains. In this paper, adaptive structures and functional twin boundaries are reviewed, and examples of various observed functionalities (e.g. superconductivity, polarity, and ferroelectricity) and corresponding twin boundary structures are provided. In addition, this review confirms that various theoretically predicted, structurally bridging low-symmetry phases do, in fact, exist. Moreover, the values of the lattice constants of the adaptive state are adjustable parameters that are determined by combinations of cubic, rhombohedral/tetragonal phases, and geometrical invariant conditions. Finally, we show that, in such cases, macroscopic properties are controlled by the unique functionality of the twin walls. Looking forward, domain boundary-dominated phenomena offer an important approach for enhancing the properties of the bulk, and to unique local properties where the "twin is the device". We encourage the community to rethink their approaches to materials by design that have treated the structure as homogeneous and to consider the alternative paradigm where the local structure is different from the apparent average symmetry. © 2014 Taylor & Francis. Source

Bell M.A.,Virginia Polytechnic Institute and State University
Child Development | Year: 2012

Fifty 8-month-old infants participated in a study of the interrelations among cognition, temperament, and electrophysiology. Better performance on a working memory task (assessed using a looking version of the A-not-B task) was associated with increases in frontal-parietal EEG coherence from baseline to task, as well as elevated levels of frontal-occipital coherence during both baseline and task. Enhanced performance was also associated with decreased heart period (increased heart rate) from baseline to task. Infants with better working memory performance had parents who rated them high on activity level and distress to limitations. When considered collectively, EEG coherence and heart period contributed unique variance in the prediction of high and low performance groups. Implications for the study of infant cognition are discussed. © 2011 The Author. Child Development © 2011 Society for Research in Child Development, Inc. Source

Falkinham III J.O.,Virginia Polytechnic Institute and State University
Emerging Infectious Diseases | Year: 2011

To determine whether plumbing could be a source of nontuberculous mycobacteria (NTM) infection, during 2007 2009 I isolated NTM from samples from household water systems of NTM patients. Samples from 22/37 (59%) households and 109/394 (28%) total samples yielded NTM. Seventeen (46%) of the 37 households yielded ≥1 Mycobacterium spp. isolate of the same species as that found in the patient; in 7 of those households, the patient isolate and 1 plumbing isolate exhibited the same repetitive sequence-based PCR DNA fingerprint. Households with water heater temperatures ≤ 125°C (≤50°C) were significantly more likely to harbor NTM compared with households with hot water temperatures ≥130°F (≥55°C) (p = 0.0107). Although households with water from public or private water systems serving multiple households were more likely to have NTM (19/27, 70%) compared with households with a well providing water to only 1 household (5/12, 42%), that difference was not significant (p = 0.1532). Source

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