930 research outputs found
Information Platform to Improve Research Utility of Clinical Study Data
The value of the results in every clinical study depends on the quality of the captured data and the analysis process. The goal is to discover and prove a scientific matter, to do this the data has to be valid, easy to access and understandable. To capture data is often a complex, time consuming process that could go on for multiple years, it's a process done for all studies. Imagine the possibility to reuse the captured data in similar future projects, it will reduce the need for capturing new data and give researchers access to more data to use in their analyzes. This thesis introduces a platform constructed for a newly formed research group, the platform is for capturing and storing data to ease the workload of the researchers in a clinical study regarding COPD. The platform will provide a standard for the captured data, the feasibility to reuse the data in future projects and improve the quality in the captured data to improve the analysis process. A web application is used, utilizing REDCap software, fo implementing the platform for this study resulting in an important tool for tracking dat
Dynamics of Bianchi type I elastic spacetimes
We study the global dynamical behavior of spatially homogeneous solutions of
the Einstein equations in Bianchi type I symmetry, where we use non-tilted
elastic matter as an anisotropic matter model that naturally generalizes
perfect fluids. Based on our dynamical systems formulation of the equations we
are able to prove that (i) toward the future all solutions isotropize; (ii)
toward the initial singularity all solutions display oscillatory behavior;
solutions do not converge to Kasner solutions but oscillate between different
Kasner states. This behavior is associated with energy condition violation as
the singularity is approached.Comment: 28 pages, 11 figure
Quasinormal behavior of the D-dimensional Schwarzshild black hole and higher order WKB approach
We study characteristic (quasinormal) modes of a -dimensional Schwarzshild
black hole. It proves out that the real parts of the complex quasinormal modes,
representing the real oscillation frequencies, are proportional to the product
of the number of dimensions and inverse horizon radius . The
asymptotic formula for large multipole number and arbitrary is derived.
In addition the WKB formula for computing QN modes, developed to the 3rd order
beyond the eikonal approximation, is extended to the 6th order here. This gives
us an accurate and economic way to compute quasinormal frequencies.Comment: 15 pages, 6 figures, the 6th order WKB formula for computing QNMs in
Mathematica is available from https://goo.gl/nykYG
Tidal torque induced by orbital decay in compact object binaries
As we observe in the moon-earth system, tidal interactions in binary systems
can lead to angular momentum exchange. The presence of viscosity is generally
regarded as the condition for such transfer to happen. In this paper, we show
how the orbital evolution can cause a persistent torque between the binary
components, even for inviscid bodies. This preferentially occurs at the final
stage of coalescence of compact binaries, when the orbit shrinks successively
by gravitational waves and plunging on a timescale shorter than the viscous
timescale. The total orbital energy transferred to the secondary by this torque
is ~0.01 of its binding energy. We further show that this persistent torque
induces a differentially rotating quadrupole perturbation. Specializing to the
case of a secondary neutron star, we find that this non equilibrium state has
an associated free energy of 10^47-10^48 erg, just prior to coalescence. This
energy is likely stored in internal fluid motions, with a sizable amount of
differential rotation. By tapping this free energy reservoir, a preexisting
weak magnetic field could be amplified up to a strength of ~10^15 Gauss. Such a
dynamically driven tidal torque can thus recycle an old neutron star into a
highly magnetized neutron star, with possible observational consequences at
merger.Comment: 14 pages, 8 figures, new sections added, accepted on Sept.19,
published on MNRA
The Fennoscandian Shield deep terrestrial virosphere suggests slow motion 'boom and burst' cycles
The deep biosphere contains members from all three domains of life along with viruses. Here we investigate the deep terrestrial virosphere by sequencing community nucleic acids from three groundwaters of contrasting chemistries, origins, and ages. These viromes constitute a highly unique community compared to other environmental viromes and sequenced viral isolates. Viral host prediction suggests that many of the viruses are associated with Firmicutes and Patescibacteria, a superphylum lacking previously described active viruses. RNA transcript-based activity implies viral predation in the shallower marine water-fed groundwater, while the deeper and more oligotrophic waters appear to be in 'metabolic standby'. Viral encoded antibiotic production and resistance systems suggest competition and antagonistic interactions. The data demonstrate a viral community with a wide range of predicted hosts that mediates nutrient recycling to support a higher microbial turnover than previously anticipated. This suggests the presence of 'kill-the-winner' oscillations creating slow motion 'boom and burst' cycles. Karin Holmfeldt et al. sequence metagenomes and metatranscriptomes of viruses in deep groundwaters down to 448m below the surface. The results reveal ecological dynamics of viruses including slow motion 'boom and burst' cycles and a 'kill the winner' model potentially driven by viral predation
Comparison of the α and β isomeric forms of the detergent n-dodecyl-D-maltoside for solubilizing photosynthetic complexes from pea thylakoid membranes
AbstractMild non-ionic detergents are indispensable in the isolation of intact integral membrane proteins and protein-complexes from biological membranes. Dodecylmaltoside (DM) belongs to this class of detergents being a glucoside-based surfactant with a bulky hydrophilic head group composed of two sugar rings and a non-charged alkyl glycoside chain. Two isomers of this molecule exist, differing only in the configuration of the alkyl chain around the anomeric center of the carbohydrate head group, axial in α-DM and equatorial in β-DM. In this paper, we have investigated the solubilizing properties of α-DM and β-DM on the isolation of photosynthetic complexes from pea thylakoids membranes maintaining their native architecture of stacked grana and stroma lamellae. Exposure of these stacked thylakoids to a single step treatment with increasing concentrations (5–100mM) of α-DM or β-DM resulted in a quick partial or complete solubilization of the membranes. Regardless of the isomeric form used: 1) at the lowest DM concentrations only a partial solubilization of thylakoids was achieved, giving rise to the release of mainly small protein complexes mixed with membrane fragments enriched in PSI from stroma lamellae; 2) at concentrations above 30mM a complete solubilization occurred with the further release of high molecular weight protein complexes identified as dimeric PSII, PSI-LHCI and PSII–LHCII supercomplexes. However, at concentrations of detergent which fully solubilized the thylakoids, the α and β isomeric forms of DM exerted a somewhat different solubilizing effect on the membranes: higher abundance of larger sized PSII–LHCII supercomplexes retaining a higher proportion of LHCII and lower amounts of PSI–LHCI intermediates were observed in α-DM treated membranes, reflecting the mildness of α-DM compared with its isomer. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial
Off-Equilibrium Dynamics in Finite-Dimensional Spin Glass Models
The low temperature dynamics of the two- and three-dimensional Ising spin
glass model with Gaussian couplings is investigated via extensive Monte Carlo
simulations. We find an algebraic decay of the remanent magnetization. For the
autocorrelation function a typical
aging scenario with a scaling is established. Investigating spatial
correlations we find an algebraic growth law of
the average domain size. The spatial correlation function scales with . The sensitivity of the
correlations in the spin glass phase with respect to temperature changes is
examined by calculating a time dependent overlap length. In the two dimensional
model we examine domain growth with a new method: First we determine the exact
ground states of the various samples (of system sizes up to )
and then we calculate the correlations between this state and the states
generated during a Monte Carlo simulation.Comment: 38 pages, RevTeX, 14 postscript figure
Gravitational Waves in Brans-Dicke Theory : Analysis by Test Particles around a Kerr Black Hole
Analyzing test particles falling into a Kerr black hole, we study
gravitational waves in Brans-Dicke theory of gravity. First we consider a test
particle plunging with a constant azimuthal angle into a rotating black hole
and calculate the waveform and emitted energy of both scalar and tensor modes
of gravitational radiation. We find that the waveform as well as the energy of
the scalar gravitational waves weakly depends on the rotation parameter of
black hole and on the azimuthal angle.
Secondly, using a model of a non-spherical dust shell of test particles
falling into a Kerr black hole, we study when the scalar modes dominate. When a
black hole is rotating, the tensor modes do not vanish even for a ``spherically
symmetric" shell, instead a slightly oblate shell minimizes their energy but
with non-zero finite value, which depends on Kerr parameter . As a result,
we find that the scalar modes dominate only for highly spherical collapse, but
they never exceed the tensor modes unless the Brans-Dicke parameter
\omega_{BD} \lsim 750 for or unless \omega_{BD} \lsim 20,000
for , where is mass of black hole.
We conclude that the scalar gravitational waves with \omega_{BD} \lsim
several thousands do not dominate except for very limited situations
(observation from the face-on direction of a test particle falling into a
Schwarzschild black hole or highly spherical dust shell collapse into a Kerr
black hole). Therefore observation of polarization is also required when we
determine the theory of gravity by the observation of gravitational waves.Comment: 24 pages, revtex, 18 figures are attached with ps file
Ideal Outcome After Pancreatoduodenectomy:A Transatlantic Evaluation of a Harmonized Composite Outcome Measure
OBJECTIVE: The aim of this study is to define and assess Ideal Outcome in the national or multicenter registries of North America, Germany, the Netherlands, and Sweden. BACKGROUND: Assessing outcomes after pancreatoduodenectomy among centers and countries requires a broad evaluation that cannot be captured by a single parameter. Previously, 2 composite outcome measures (textbook outcome and optimal pancreatic surgery) for pancreatoduodenectomy have been described from Europe and the United States. These composites were harmonized into ideal outcome (IO). METHODS: This analysis is a transatlantic retrospective study (2018-2020) of patients after pancreatoduodenectomy within the registries from North America, Germany, The Netherlands, and Sweden. After 3 consensus meetings, IO for pancreatoduodenectomy was defined as the absence of all 6 parameters: (1) in-hospital mortality, (2) severe complications-Clavien-Dindo ≥3, (3) postoperative pancreatic fistula-International Study Group of Pancreatic Surgery (ISGPS) grade B/C, (4) reoperation, (5) hospital stay >75th percentile, and (6) readmission. Outcomes were evaluated using relative largest difference (RLD) and absolute largest difference (ALD), and multivariate regression models. RESULTS: Overall, 21,036 patients after pancreatoduodenectomy were included, of whom 11,194 (54%) reached IO. The rate of IO varied between 55% in North America, 53% in Germany, 52% in The Netherlands, and 54% in Sweden (RLD: 1.1, ALD: 3%, P <0.001). Individual components varied with an ALD of 2% length of stay, 4% for in-hospital mortality, 12% severe complications, 10% postoperative pancreatic fistula, 11% reoperation, and 9% readmission. Age, sex, absence of chronic obstructive pulmonary disease, body mass index, performance status, American Society of Anesthesiologists (ASA) score, biliary drainage, absence of vascular resection, and histologic diagnosis were associated with IO. In the subgroup of patients with pancreatic adenocarcinoma, country, and neoadjuvant chemotherapy also was associated with improved IO. CONCLUSIONS: The newly developed composite outcome measure "Ideal Outcome" can be used for auditing and comparing outcomes after pancreatoduodenectomy. The observed differences can be used to guide collaborative initiatives to further improve the outcomes of pancreatic surgery.</p
- …