1,513 research outputs found
Instanton contribution to the Sivers function
We study the Sivers function for valence u and d quarks in the proton within
the instanton model for QCD vacuum, adopting the MIT bag model wave functions
for quarks. Within approaches based on perturbative one-gluon final state
interactions a non-zero value of the Sivers function is related to the presence
of both S and P wave components in quark wave functions. We show that the
instanton-induced chromomagnetic, nonperturbative interaction leads to very
specific spin-spin correlations between the struck and spectator quarks,
resulting in a non-trivial flavour dependence of the Sivers function.
Comparison of the obtained Sivers functions with phenomenological
parameterizations is discussed.Comment: 1+12 pages, 4 ps figures; v2: few references and one sentence added
in the introduction; final version published in Phys. Lett.
Deep Proteomics of Mouse Skeletal Muscle Enables Quantitation of Protein Isoforms, Metabolic Pathways, and Transcription Factors
Skeletal muscle constitutes 40% of individual body mass and plays vital roles in locomotion and whole-body metabolism. Proteomics of skeletal muscle is challenging because of highly abundant contractile proteins that interfere with detection of regulatory proteins. Using a state-of-the art MS workflow and a strategy to map identifications from the C2C12 cell line model to tissues, we identified a total of 10,218 proteins, including skeletal muscle specific transcription factors like myod1 and myogenin and circadian clock proteins. We obtain absolute abundances for proteins expressed in a muscle cell line and skeletal muscle, which should serve as a valuable resource. Quantitation of protein isoforms of glucose uptake signaling pathways and in glucose and lipid metabolic pathways provides a detailed metabolic map of the cell line compared with tissue. This revealed unexpectedly complex regulation of AMP-activated protein kinase and insulin signaling in muscle tissue at the level of enzyme isoforms
Single muscle fiber proteomics reveals unexpected mitochondrial specialization
Mammalian skeletal muscles are composed of multinucleated cells termed slow or fast fibers according to their contractile and metabolic properties. Here, we developed a high-sensitivity workflow to characterize the proteome of single fibers. Analysis of segments of the same fiber by traditional and unbiased proteomics methods yielded the same subtype assignment. We discovered novel subtype-specific features, most prominently mitochondrial specialization of fiber types in substrate utilization. The fiber type-resolved proteomes can be applied to a variety of physiological and pathological conditions and illustrate the utility of single cell type analysis for dissecting proteomic heterogeneity
Intrinsic parton motion soft mechanisms and the longitudinal spin asymmetry A_LL in high energy pp -> pi X
The longitudinal double spin asymmetry A_LL in the reaction pp --> pi X has
been measured at RHIC with extremely interesting consequences. If the gluon
polarization in a proton were as big as needed to resolve the famous "spin
crisis" then A_LL would be large and positive. Latest RHIC results indicate
that A_LL is small and disfavour large positive values of the gluon
polarization. We examine whether the soft mechanisms (Collins, Sivers,
Boer-Mulders), essential for generating transverse single spin asymmetries,
have any significant influence on A_LL, and whether they could alter the
conclusion that the gluon polarization is necessarily small. It turns out that
the contribution from these effects is essentially negligible.Comment: RevTeX, 9 pages, 3 eps figures. Revised and shortened version; title
slightly modified; figs. 3,4 removed; a new figure for the unpol. cross
section added; no changes in results and conclusions; matches the published
versio
Glueball production in radiative J/psi, Upsilon decays
Using a bound-state model of weakly bound gluons for glueballs made of two
gluons and a natural generalization of the perturbative QCD formalism for
exclusive hadronic processes, we present results for glueball production in
radiative J/psi, Upsilon decays into several possible glueball states,
including L \not= 0 ones. We perform a detailed phenomenological analysis,
presenting results for the more favored experimental candidates and for decay
angular distributions.Comment: RevTeX4, 26 pages, 11 eps figure
LOFAR discovery of a 700-kpc remnant radio galaxy at low redshift
Remnant radio galaxies represent the final dying phase of radio galaxy
evolution, in which the jets are no longer active. Due to their rarity in flux
limited samples and the difficulty of identification, this dying phase remains
poorly understood and the luminosity evolution largely unconstrained. Here we
present the discovery and detailed analysis of a large (700 kpc) remnant radio
galaxy with a low surface brightness that has been identified in LOFAR images
at 150 MHz. By combining LOFAR data with new follow-up Westerbork observations
and archival data at higher frequencies, we investigated the source morphology
and spectral properties from 116 to 4850 MHz. By modelling the radio spectrum
we probed characteristic timescales of the radio activity. The source has a
relatively smooth, diffuse, amorphous appearance together with a very weak
central compact core which is associated with the host galaxy located at
z=0.051. From our ageing and morphological analysis it is clear that the
nuclear engine is currently switched off or, at most, active at a very low
power state. The host galaxy is currently interacting with another galaxy
located at a projected separation of 15 kpc and a radial velocity offset of 300
km/s. This interaction may have played a role in the triggering and/or shut
down of the radio jets. The spectral shape of this remnant radio galaxy differs
from the majority of the previously identified remnant sources, which show
steep or curved spectra at low to intermediate frequencies. In light of this
finding and in preparation for new-generation deep low-frequency surveys, we
discuss the selection criteria to be used to select representative samples of
these sources.Comment: 10 pages, 6 figures, 5 tables, A&A accepte
3rd KidRec workshop: What does good look like?
Today's children spend considerable time online, searching and receiving information from various websites and apps. While searching for information, e.g. for school or hobbies, children use search systems to locate resources and receive site recommendations that might be useful for them. The call for good, reliable, child-friendly systems has been made many times and the thesis that the algorithms of "adult" information systems are not necessarily suitable or fair for children is widely accepted. However, there is still no clear and balanced view on what makes one search/recommendation system for children good or better than other systems, nor on what content should be considered "good enough to be retrieved" or recommended. The goal of this workshop is to bring together researchers and practitioners in education, child-development, computer science, and more who can address this questions while considering issues related to education, algorithms, ethics, privacy, evaluation
Dissecting the Pharmacodynamics and Pharmacokinetics of MSCs to Overcome Limitations in Their Clinical Translation
Recently, mesenchymal stromal stem cells (MSCs) have been proposed as therapeutic agents because of their promising preclinical features and good safety profile. However, their introduction into clinical practice has been associated with a suboptimal therapeutic profile. In this review, we address the biodistribution of MSCs in preclinical studies with a focus on the current understanding of the pharmacodynamics (PD) and pharmacokinetics (PK) of MSCs as key aspects to overcome unsatisfactory clinical benefits of MSC application. Beginning with evidence of MSC biodistribution and highlighting PK and PD factors, a new PK-PD model is also proposed. According to this theory, MSCs and their released factors are key players in PK, and the efficacy biomarkers are considered relevant for PD in more predictive preclinical investigations. Accounting for the PK-PD relationship in MSC translational research and proposing new models combined with better biodistribution studies could allow realization of the promise of more robust MSC clinical translation. The number of clinical trials based on MSCs that are publicly available exceeds 800; however, data regarding MSC pharmacodynamics (PD), pharmacokinetics (PK), and biodistribution are still scarce. For this reason, we dissected the PD and PK properties of MSCs, presenting factors that may influence MSC-based PK studies to then conceive a new PK-PD model that would support better and more robust MSC clinical translation
Root Fractures in the Primary Teeth and Their Management: A Scoping Review
(1) Background: Traumatic dental injuries constitute a major global health problem. Primary deciduous teeth of the upper frontal group are frequently affected by trauma, especially at an early age. It is important to treat primary traumatic injuries because early tooth loss can lead to aesthetic and functional alterations. The most common injuries are extrusion, lateral luxation, and intrusion. Root fracture is a less common complication that can lead to tooth extraction if not properly diagnosed and managed. However, there are a lack of data regarding primary root fracture treatment. The literature was reviewed to study the current knowledge on the treatment of these injuries, and to propose an operative protocol based on the results obtained. (2) Methods: A literature search was performed on Web of Science, PubMed/MEDLINE, and SCOPUS. The research focused on the following features: age of the patient; localization of the root fracture and type of displacement suffered (intrusive, extrusive, or lateral); type of emergency treatment or diagnostic test performed and their compliance with IADT guidelines; follow-up duration. (2) Results: Only 8 articles fully met the inclusion criteria, with a total of 46 patients and 62 root fractures. Out of a total of 62 root fractures, regarding only upper incisors, the most common treatment was splinting (n = 39) for a period ranging from 3 weeks to 3 months (with an average of six weeks). No treatment was performed for 23 of the root fractures. The splinting performed in most of the included cases was semi-rigid, with the splint held in place using a composite resin material. An orthodontic splint using brackets and 0.5 mm stainless steel wire was used in only in one study. (4) Conclusions: We deduced that the root fracture of primary teeth is a rare traumatic dental injury that can cause numerous complications, such as eruptive problems in the permanent teeth. Correct radiological diagnosis, immediate repositioning and semi-rigid splinting could be conservative methods to prevent premature tooth loss in very young patients
charmonium state decay into in QCD models including constituent quark mass corrections
Stimulated by the experimental observation, made by the E760 Collaboration at
Fermilab, of the state of charmonium resonantly formed in
annihilation, we perform a calculation of the decay width for the process. To this end, we employ a phenomenological model which adds
constituent quark mass corrections to the usual massless QCD models for
exclusive processes. For massless models, in fact, the process under
consideration is forbidden by the so-called helicity selection rules, while it
is allowed in our extended model. We find to be
in the range eV. We also compare our results with previous, indirect
estimates, based on QCD multipole expansion models.Comment: 17 pages, REVTeX 3.0, 1 postscript figure included. Revised version,
to be published in Physical Review D. Brief discussion of the role of other
nonperturbative effects and three references added in the introduction;
Comparison with QCD multipole expansion model slightly reformulated; Some
sentences added in the conclusions; Results unchange
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