239 research outputs found
The accumulation of plutonium isotopes (239+240) in the components of the natural environment in the territory of the Karaganda region adjacent to the Semipalatinsk test site
Presents the results of a radiological survey of the territory of the Karaganda region. The data obtained on contamination of isotopes of plutonium (239+240), assessed the impact of nuclear testing on Semipalatinsk testing nuclear polygon. Currently, the pollution of the examined areas of technogenic radionuclides in most places, does not exceed the background level of global fallout, and only at some points noted in the reading background of global fallout. However, there are local areas of contamination, which could be formed as a result of testing of BRV, or other atmospheric fallout from nuclear testing
Dynamics of end to end loop formation for an isolated chain in viscoelastic fluid
We theoretically investigate the looping dynamics of a linear polymer
immersed in a viscoelastic fluid. The dynamics of the chain is governed by a
Rouse model with a fractional memory kernel recently proposed by Weber et al.
(S. C. Weber, J. A. Theriot, and A. J. Spakowitz, Phys. Rev. E 82, 011913
(2010)). Using the Wilemski-Fixman (G. Wilemski and M. Fixman, J. Chem. Phys.
60, 866 (1974)) formalism we calculate the looping time for a chain in a
viscoelastic fluid where the mean square displacement of the center of mass of
the chain scales as t^(1/2). We observe that the looping time is faster for the
chain in viscoelastic fluid than for a Rouse chain in Newtonian fluid up to a
chain length and above this chain length the trend is reversed. Also no scaling
of the looping time with the length of the chain seems to exist for the chain
in viscoelastic fluid
A streamlined mass spectrometry-based proteomics workflow for large scale FFPE tissue analysis
Formalin fixation and paraffin-embedding (FFPE) is the most common method to preserve human tissue for clinical diagnosis, and FFPE archives represent an invaluable resource for biomedical research. Proteins in FFPE material are stable over decades but their efficient extraction and streamlined analysis by mass spectrometry (MS)-based proteomics has so far proven challenging. Herein we describe a MS-based proteomic workflow for quantitative profiling of large FFPE tissue cohorts directly from histopathology glass slides. We demonstrate broad applicability of the workflow to clinical pathology specimens and variable sample amounts, including low-input cancer tissue isolated by laser microdissection. Using state-of-the-art data dependent acquisition (DDA) and data independent acquisition (DIA) MS workflows, we consistently quantify a large part of the proteome in 100 min single-run analyses. In an adenoma cohort comprising more than 100 samples, total workup took less than a day. We observed a moderate trend towards lower protein identification in long-term stored samples (>15 years), but clustering into distinct proteomic subtypes was independent of archival time. Our results underscore the great promise of FFPE tissues for patient phenotyping using unbiased proteomics and they prove the feasibility of analyzing large tissue cohorts in a robust, timely, and streamlined manner
Frustrated H-Induced Instability of Mo(110)
Using helium atom scattering Hulpke and L"udecke recently observed a giant
phonon anomaly for the hydrogen covered W(110) and Mo(110) surfaces. An
explanation which is able to account for this and other experiments is still
lacking. Below we present density-functional theory calculations of the atomic
and electronic structure of the clean and hydrogen-covered Mo(110) surfaces.
For the full adsorbate monolayer the calculations provide evidence for a strong
Fermi surface nesting instability. This explains the observed anomalies and
resolves the apparent inconsistencies of different experiments.Comment: 4 pages, 2 figures, submitted to PR
Correlation chemical shift imaging with low-power adiabatic pulses and constant-density spiral trajectories
In this work we introduce the concept of correlation chemical shift imaging (CCSI). Novel CCSI pulse sequences are demonstrated on clinical scanners for two-dimensional Correlation Spectroscopy (COSY) and Total Correlation Spectroscopy (TOCSY) imaging experiments. To date there has been limited progress reported towards a feasible and robust multivoxel 2D COSY. Localized 2D TOCSY imaging is shown for the first time in this work. Excitation with adiabatic GOIA-W(16,4) pulses (Gradient Offset Independent Adiabaticity Wurst modulation) provides minimal chemical shift displacement error, reduced lipid contamination from subcutaneous fat, uniform optimal flip angles, and efficient mixing for coupled spins, while enabling short repetition times due to low power requirements. Constant-density spiral readout trajectories are used to acquire simultaneously two spatial dimensions and f2 frequency dimension in (kx,ky,t2) space in order to speed up data collection, while f1 frequency dimension is encoded by consecutive time increments of t1 in (kx,ky,t1,t2) space. The efficient spiral sampling of the k-space enables the acquisition of a single-slice 2D COSY dataset with an 8 × 8 matrix in 8:32 min on 3 T clinical scanners, which makes it feasible for in vivo studies on human subjects. Here we present the first results obtained on phantoms, human volunteers and patients with brain tumors. The patient data obtained by us represent the first clinical demonstration of a feasible and robust multivoxel 2D COSY. Compared to the 2D J-resolved method, 2D COSY and TOCSY provide increased spectral dispersion which scales up with increasing main magnetic field strength and may have improved ability to unambiguously identify overlapping metabolites. It is expected that the new developments presented in this work will facilitate in vivo application of 2D chemical shift correlation MRS in basic science and clinical studies.National Institutes of Health (U.S.) (NIH grant R01 1200-206456)National Institutes of Health (U.S.) (NIH grant R01 EB007942)Siemens Aktiengesellschaft (Siemens-MIT Alliance
The role of the right temporoparietal junction in perceptual conflict: detection or resolution?
The right temporoparietal junction (rTPJ) is a polysensory cortical area that plays a key role in perception and awareness. Neuroimaging evidence shows activation of rTPJ in intersensory and sensorimotor conflict situations, but it remains unclear whether this activity reflects detection or resolution of such conflicts. To address this question, we manipulated the relationship between touch and vision using the so-called mirror-box illusion. Participants' hands lay on either side of a mirror, which occluded their left hand and reflected their right hand, but created the illusion that they were looking directly at their left hand. The experimenter simultaneously touched either the middle (D3) or the ring finger (D4) of each hand. Participants judged, which finger was touched on their occluded left hand. The visual stimulus corresponding to the touch on the right hand was therefore either congruent (same finger as touch) or incongruent (different finger from touch) with the task-relevant touch on the left hand. Single-pulse transcranial magnetic stimulation (TMS) was delivered to the rTPJ immediately after touch. Accuracy in localizing the left touch was worse for D4 than for D3, particularly when visual stimulation was incongruent. However, following TMS, accuracy improved selectively for D4 in incongruent trials, suggesting that the effects of the conflicting visual information were reduced. These findings suggest a role of rTPJ in detecting, rather than resolving, intersensory conflict
Cytopathic bovine viral diarrhea viruses (BVDV): emerging pestiviruses doomed to extinction
Bovine viral diarrhea virus (BVDV), a Flaviviridae pestivirus, is arguably one of the most widespread cattle pathogens worldwide. Each of its two genotypes has two biotypes, non-cytopathic (ncp) and cytopathic (cp). Only the ncp biotype of BVDV may establish persistent infection in the fetus when infecting a dam early in gestation, a time point which predates maturity of the adaptive immune system. Such fetuses may develop and be born healthy but remain infected for life. Due to this early initiation of fetal infection and to the expression of interferon antagonistic proteins, persistently infected (PI) animals remain immunotolerant to the infecting viral strain. Although only accounting for some 1% of all animals in regions where BVDV is endemic, PI animals ensure the viral persistence in the host population. These animals may, however, develop the fatal mucosal disease, which is characterized by widespread lesions in the gastrointestinal tract. Cp BVD virus, in addition to the persisting ncp biotype, can be isolated from such animals. The cp viruses are characterized by unrestrained genome replication, and their emergence from the persisting ncp ones is due to mutations that are unique in each virus analyzed. They include recombinations with host cell mRNA, gene translocations and duplications, and point mutations. Cytopathic BVD viruses fail to establish chains of infection and are unable to cause persistent infection. Hence, these viruses illustrate a case of “viral emergence to extinction” – irrelevant for BVDV evolution, but fatal for the PI host
When do Acquirers Invest in the R&D Assets of Acquired Science-based Firms in Cross-border Acquisitions? The Role of Technology and Capabilities Similarity and Complementarity
Drawing on a multiple case study of acquisitions of UK biopharmaceutical firms, we develop an analytical framework that elucidates how key determinants of the knowledge base of science-based firms and their combinations through M&As interact and affect post-acquisition investment in the target’s R&D projects. We show that two factors — the complementarity/similarity of the technology, and the complementarity/similarity of the discovery and development capabilities of the target and acquiring firm — interact to produce different outcomes in terms of investment in the acquired firm’s R&D assets and for the local science and technology system
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