5,640 research outputs found
Twist-2 Generalized TMDs and the Spin/Orbital Structure of the Nucleon
Generalized transverse-momentum dependent parton distributions (GTMDs) encode
the most general parton structure of hadrons. Here we focus on two twist-2
GTMDs which are denoted by and in parts of the literature.
As already shown previously, both GTMDs have a close relation to orbital
angular momentum of partons inside a hadron. However, recently even the mere
existence of and has been doubted. We explain why this
claim does not hold. We support our model-independent considerations by
calculating the two GTMDs in the scalar diquark model and in the quark-target
model, where we also explicitly check the relation to orbital angular momentum.
In addition, we compute and at large transverse momentum in
perturbative Quantum Chromodynamics and show that they are nonzero.Comment: 29 pages, 6 figures; two clarifications and a reference added;
version to appear in Phys. Rev.
Determination of the lowest energy structure of Ag from first-principles calculations
The ground-state electronic and structural properties, and the electronic
excitations of the lowest energy isomers of the Ag cluster are calculated
using density functional theory (DFT) and time-dependent DFT (TDDFT) in real
time and real space scheme, respectively. The optical spectra provided by TDDFT
predict that the D dodecahedron isomer is the structural minimum of
Ag cluster. Indeed, it is borne out by the experimental findings.Comment: 4 pages, 2 figures. Accepted in Physical Review A as a brief repor
A simple method for isolation of PCR fragments from silver-stained polyacrylamide gels by scratching with a fine needle
This project investigated how NoSQL databases can be used together with a logical layer, instead of a relational database with separated backend logic, to search for products with customer specific constraints in an e-commerce scenario. The motivation behind moving from a relational database was the scalability issues and increased read latencies experienced as the data increased. The work resulted in a framework called Cauldron that uses pipelines a sequence of execution steps to expose its data stored in an in-memory key-value store and a document database. Cauldron uses write replication between distributed instances to increase read throughput at the cost of write latency. A product database with customer specific constraints was implemented using Cauldron to compare it against an existing solution based on a relational database. The new product database can serve search queries 10 times faster in the general case and up to 25 times faster in extreme cases compared to the existing solution.Projektet undersökte hur NoSQL databaser tillsammans med ett logiskt lager, istället för en relationsdatabas med separat backend logik, kan användas för att söka på produkter med kundunika restriktioner. Motivationen till att byta ut relationsdatabasen berodde på skalbarhetsproblem och långsammare svarstider när datamängden ökade. Arbetet resulterade i ett ramverk vid namn Cauldron som använder pipelines sammankopplade logiska steg för att exponera sin data från en minnesbunden nyckel-värde-databas och en dokumentdatabas. Cauldron använder replikering mellan distribuerade instanser för att öka läsgenomstömmningen på bekostnad av högre skrivlatenser. En produktdatabas med kundunika restriktioner implementerades med hjälp av Cauldron för att jämföra den mot en befintlig lösning baserad på en relationsdatabas. Den nya databasen kan besvara sökförfrågningar 10 gånger snabbare i normalfallen och upp till 25 gånger snabbare i extremfallen jämfört med den befintliga lösningen
Pfleiderer2: identification of a new globular cluster in the Galaxy
We provide evidence that indicate the star cluster Pfleiderer 2, which is
projected in a rich field, as a newly identified Galactic globular cluster.
Since it is located in a crowded field, core extraction and decontamination
tools were applied to reveal the cluster sequences in B, V and I
Color-Magnitude Diagrams (CMDs). The main CMD features of Pfleiderer 2 are a
tilted Red Giant Branch, and a red Horizontal Branch, indicating a high
metallicity around solar. The reddening is E(B-V)=1.01. The globular cluster is
located at a distance from the Sun d = 162 kpc.
The cluster is located at 2.7 kpc above the Galactic plane and at a distance
from the Galactic center of R=9.7 kpc, which is unusual for a
metal-rich globular cluster.Comment: Accepted by The Astronomical Journa
The Ultimate Light Curve of SN 1998bw/GRB 980425
We present multicolor light curves of SN 1998bw which appeared in ESO184-G82
in close temporal and spacial association with GRB 980425. They are based on
observations done at Cerro Tololo Inter-American Observatory and data from the
literature. The CTIO photometry reaches ~86 days after the GRB in and ~160
days after the GRB in BV(RI)_C. The observations in U extend by about 30 days
the previously known coverage, and determine the slope of the early exponential
tail.
We calibrate a large set of local standards in common with those of previous
studies and use them to transform published observations of the SN to our
realization of the standard photometric system. We show that the photometry
from different sources merges smoothly and provide a unified set of 300
observations of the SN in five bands. Using the extensive set of spectra in
public domain we compute extinction and K corrections, and build
quasi-bolometric unreddened rest frame light curves. We provide low degree
piecewise spline fits to these light curves with daily sampling. They reach ~86
rest frame days after the GRB with U band coverage, and ~498 rest frame days
after the GRB without U.Comment: 38 pages, 5 figures, 3 table
Device and Method for Digital-To-Analog Transformations and Reconstructions of Multi-Channel Electrocardiograms
The present invention includes a method and apparatus for digital to analog conversion and reconstruction of multichannel electrocardiograms. The method may include receiving digital information representative of a plurality of independent signals, producing a plurality of analog outputs from said digital information wherein a first analog output is designated as a common reference, and imposing a predetermined voltage on a second analog output with respect to said common reference, which provides for a substantial recreation of the original independent signals. The apparatus may comprise a processor operable for receiving digital information representative of independent lead signals from a first ECG machine and digital to analog circuitry for substantially reproducing the original lead signals for analysis on a second ECG machine for convenient and efficient second opinions of cardiac data
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