1,102 research outputs found
Clues to NaCN formation
ALMA is providing us essential information on where certain molecules form.
Observing where these molecules emission arises from, the physical conditions
of the gas, and how this relates with the presence of other species allows us
to understand the formation of many species, and to significantly improve our
knowledge of the chemistry that occurs in the space. We studied the molecular
distribution of NaCN around IRC +10216, a molecule detected previously, but
whose origin is not clear. High angular resolution maps allow us to model the
abundance distribution of this molecule and check suggested formation paths. We
modeled the emission of NaCN assuming local thermal equilibrium (LTE)
conditions. These profiles were fitted to azimuthal averaged intensity profiles
to obtain an abundance distribution of NaCN. We found that the presence of NaCN
seems compatible with the presence of CN, probably as a result of the
photodissociation of HCN, in the inner layers of the ejecta of IRC +10216.
However, similar as for CH 3 CN, current photochemical models fail to reproduce
this CN reservoir. We also found that the abundance peak of NaCN appears at a
radius of 3 x 10 15 cm, approximately where the abundance of NaCl, suggested to
be the parent species, starts to decay. However, the abundance ratio shows that
the NaCl abundance is lower than that obtained for NaCN. We expect that the LTE
assumption might result in NaCN abundances higher than the real ones. Updated
photochemical models, collisional rates, and reaction rates are essential to
determine the possible paths of the NaCN formation.Comment: 7 pages, 10 figures. Accepted for publication in A&A letter
PMCTrack: Delivering performance monitoring counter support to the OS scheduler
Hardware performance monitoring counters (PMCs) have proven effective in characterizing application performance. Because PMCs can only be accessed directly at the OS privilege level, kernellevel tools must be developed to enable the end-user and userspace programs to access PMCs. A large body of work has demonstrated that the OS can perform effective runtime optimizations in multicore systems by leveraging performance-counter data. Special attention has been paid to optimizations in the OS scheduler. While existing performance monitoring tools greatly simplify the collection of PMC application data from userspace, they do not provide an architecture-agnostic kernel-level mechanism that is capable of exposing high-level PMC metrics to OS components, such as the scheduler. As a result, the implementation of PMC-based OS scheduling schemes is typically tied to specific processor models. To address this shortcoming we present PMCTrack, a novel tool for the Linux kernel that provides a simple architecture-independent mechanism that makes it possible for the OS scheduler to access per-thread PMC data. Despite being an OSoriented tool, PMCTrack still allows the gathering of monitoring data from userspace, enabling kernel developers to carry out the necessary offline analysis and debugging to assist them during the scheduler design process. In addition, the tool provides both the OS and the user-space PMCTrack components with other insightful metrics available in modern processors and which are not directly exposed as PMCs, such as cache occupancy or energy consumption. This information is also of great value when it comes to analyzing the potential benefits of novel scheduling policies on real systems. In this paper, we analyze different case studies that demonstrate the flexibility, simplicity and powerful features of PMCTrack.Facultad de InformáticaInstituto de Investigación en Informátic
PMCTrack: Delivering performance monitoring counter support to the OS scheduler
Hardware performance monitoring counters (PMCs) have proven effective in characterizing application performance. Because PMCs can only be accessed directly at the OS privilege level, kernellevel tools must be developed to enable the end-user and userspace programs to access PMCs. A large body of work has demonstrated that the OS can perform effective runtime optimizations in multicore systems by leveraging performance-counter data. Special attention has been paid to optimizations in the OS scheduler. While existing performance monitoring tools greatly simplify the collection of PMC application data from userspace, they do not provide an architecture-agnostic kernel-level mechanism that is capable of exposing high-level PMC metrics to OS components, such as the scheduler. As a result, the implementation of PMC-based OS scheduling schemes is typically tied to specific processor models. To address this shortcoming we present PMCTrack, a novel tool for the Linux kernel that provides a simple architecture-independent mechanism that makes it possible for the OS scheduler to access per-thread PMC data. Despite being an OSoriented tool, PMCTrack still allows the gathering of monitoring data from userspace, enabling kernel developers to carry out the necessary offline analysis and debugging to assist them during the scheduler design process. In addition, the tool provides both the OS and the user-space PMCTrack components with other insightful metrics available in modern processors and which are not directly exposed as PMCs, such as cache occupancy or energy consumption. This information is also of great value when it comes to analyzing the potential benefits of novel scheduling policies on real systems. In this paper, we analyze different case studies that demonstrate the flexibility, simplicity and powerful features of PMCTrack.Facultad de InformáticaInstituto de Investigación en Informátic
Origin of the surface metallization in single-domain K/Si(100)2x1
The electronic structure and the metallization onset of single-domain K/Si(100)2x1 have been investigated with angle-resolved polarization-sensitive ultraviolet photoemission. The electronic states producing the surface metallization have been studied for increasing K coverages up to room-temperature saturation. As K coverage increases, the interface undergoes a transition at a critical coverage, from a low-coverage semiconducting phase, to a saturation-coverage metallic phase. Two different surface states (F-1 and F-2) have been detected in the vicinity of the Fermi level. These two states are sequentially filled along the metallization process. The coverage dependence of both F-1 and F-2, and their symmetry properties indicate that the metallization is due to the filling of an initially empty surface band (appearance of F-2) We relate F-1 to the completion of K chains in the single-domain surface. The changes detected in K 3p line shape correlate well with the modifications of the valence band, and support that the surface remains semiconducting up to the filling of F-2
Dibucaine in Ionic-Gradient Liposomes: Biophysical, Toxicological, and Activity Characterization
Administration of local anesthetics is one of the most effective pain control techniques for postoperative analgesia. However, anesthetic agents easily diffuse into the injection site, limiting the time of anesthesia. One approach to prolong analgesia is to entrap local anesthetic agents in nanostructured carriers (e.g., liposomes). Here, we report that using an ammonium sulphate gradient was the best strategy to improve the encapsulation (62.6%) of dibucaine (DBC) into liposomes. Light scattering and nanotracking analyses were used to characterize vesicle properties, such as, size, polydispersity, zeta potentials, and number. In vitro kinetic experiments revealed the sustained release of DBC (50% in 7 h) from the liposomes. In addition, in vitro (3T3 cells in culture) and in vivo (zebrafish) toxicity assays revealed that ionic-gradient liposomes were able to reduce DBC cyto/cardiotoxicity and morphological changes in zebrafish larvae. Moreover, the anesthesia time attained after infiltrative administration in mice was longer with encapsulated DBC (27 h) than that with free DBC (11 h), at 320 μM (0.012%), confirming it as a promising long-acting liposome formulation for parenteral drug administration of dibucaine.Fil: Couto, Verônica M.. Universidade Estadual de Campinas; BrasilFil: Prieto, Maria Jimena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Multidisciplinario de Biología Celular. Grupo Vinculado al IMBICE - Grupo de Biología Estructural y Biotecnología-Universidad Nacional de Quilmes - GBEyB | Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Multidisciplinario de Biología Celular. Grupo Vinculado al IMBICE - Grupo de Biología Estructural y Biotecnología-Universidad Nacional de Quilmes - GBEyB | Universidad Nacional de la Plata. Instituto Multidisciplinario de Biología Celular. Grupo Vinculado al IMBICE - Grupo de Biología Estructural y Biotecnología-Universidad Nacional de Quilmes - GBEyB; ArgentinaFil: Igartúa, Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Multidisciplinario de Biología Celular. Grupo Vinculado al IMBICE - Grupo de Biología Estructural y Biotecnología-Universidad Nacional de Quilmes - GBEyB | Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Multidisciplinario de Biología Celular. Grupo Vinculado al IMBICE - Grupo de Biología Estructural y Biotecnología-Universidad Nacional de Quilmes - GBEyB | Universidad Nacional de la Plata. Instituto Multidisciplinario de Biología Celular. Grupo Vinculado al IMBICE - Grupo de Biología Estructural y Biotecnología-Universidad Nacional de Quilmes - GBEyB; ArgentinaFil: Feas, Daniela Agustina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Multidisciplinario de Biología Celular. Grupo Vinculado al IMBICE - Grupo de Biología Estructural y Biotecnología-Universidad Nacional de Quilmes - GBEyB | Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Multidisciplinario de Biología Celular. Grupo Vinculado al IMBICE - Grupo de Biología Estructural y Biotecnología-Universidad Nacional de Quilmes - GBEyB | Universidad Nacional de la Plata. Instituto Multidisciplinario de Biología Celular. Grupo Vinculado al IMBICE - Grupo de Biología Estructural y Biotecnología-Universidad Nacional de Quilmes - GBEyB; ArgentinaFil: Ribeiro, Lígia N.M.. Universidade Estadual de Campinas; BrasilFil: Silva, Camila M.G.. Universidade Estadual de Campinas; BrasilFil: Castro, Simone R.. Universidade Estadual de Campinas; BrasilFil: Guilherme, Viviane A.. Universidade Estadual de Campinas; BrasilFil: Dantzger, Darlene D.. Universidade Estadual de Campinas; BrasilFil: Machado, Daisy. Universidade Estadual de Campinas; BrasilFil: Alonso, Silvia del Valle. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Multidisciplinario de Biología Celular. Grupo Vinculado al IMBICE - Grupo de Biología Estructural y Biotecnología-Universidad Nacional de Quilmes - GBEyB | Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Multidisciplinario de Biología Celular. Grupo Vinculado al IMBICE - Grupo de Biología Estructural y Biotecnología-Universidad Nacional de Quilmes - GBEyB | Universidad Nacional de la Plata. Instituto Multidisciplinario de Biología Celular. Grupo Vinculado al IMBICE - Grupo de Biología Estructural y Biotecnología-Universidad Nacional de Quilmes - GBEyB; ArgentinaFil: de Paula, Eneida. Universidade Estadual de Campinas; Brasi
Artrosis postraumática en pacientes con fractura-luxacion de Lisfranc.
La artrosis postraumática es una de las complicaciones más frecuentes y más invalidantes de la
fractura-luxación de Lisfranc (FLL).
Objetivo
. Evaluar el grado de incidencia de artrosis postraumática como
complicación y secuela en pacientes con fractura-luxación de Lisfranc y valorar qué factores muestran relación
directa o influyen en su aparición y desarrollo.
Material y Método
. Se realizó un estudio de cohortes ambispectivo
transversal de 83 pacientes con diagnóstico de fractura-luxación de Lisfranc. Se utilizó un protocolo de recogida
de datos con variables relacionadas con la lesión, parámetros clínicos, terapéuticos, complicaciones y escalas de
valoración clínica. La valoración de artrosis se realiza mediante aparición de signos radiológicos de la clasifica
-
ción radiológica de Kellgren y Lawrence y su correlación clínica con presencia de dolor.
Resultados
. La artrosis
se mostró como un factor influyente en los resultados, puntuaciones regulares y malas presentan mayor tasa de
artrosis (p=0,001), y en cuanto al grado de artrosis, los casos más graves de artrosis se situaban en el grupo de
puntuaciones malas (p=0,025). Este grupo de pacientes presentaron peores puntuaciones porque referían más
dolor, mayor consumo de analgésicos, más limitación de las actividades de la vida diaria, de las actividades
deportivas y limitación de la distancia caminada.
Conclusiones
. La artrosis se mostró como un factor influyente
en los resultados (p=0,001). Los pacientes que desarrollaron artrosis tardaron más tiempo en reincorporarse a
su empleo o actividad laboral previa, tenían un tiempo más demorado desde la cirugía al alta y mayor número
total de incapacidades laborales y compensaciones económicas con respecto a los pacientes que no desarrollaron
artrosis, siendo todos estos valores estadísticamente significativos.The posttraumatic degenerative osteoarthritis is one of the most frequent complications and more
disabling of Lisfranc's fracture - luxation (FLL).
Objetive. Evaluate the degree of frequency of posttraumatic
degenerative osteoarthritis as complication and adverse effect in patients with Lisfranc's fracture - luxation and
value what factors show straight relation or influence in its appearance and development.
Material and Method.We have made a transversal prospective and retrospective study of cohorts on 83 patients with diagnosis of
Lisfranc's fracture - luxation. We have used a data collecting protocol of items related to the injury, clinical,
therapeutic parameters, complications and scales of clinical valuation. The assessment valuation of degenerative
osteoarthritis is made under radiological signs realized by means of appearance of radiological signs of Kellgren
and Lawrence classification and clinical correlation with presence of pain.
Results
. The degenerative osteoarthri
tis appeared as an influential factor in the results, regular and bad punctuations present major rate of degenerative
osteoarthritis (p=0,001), and as for the degree of degenerative osteoarthritis, the most serious cases of degenerative osteoarthritis were placing in the group of bad punctuations (p=0,025). This group of patients presented
worse punctuations because they were recounting more pain, major consumption of analgesics, more limitation
of the activities of the daily life, of the sports activities and limitation of the travelled distance.
Conclusions
. The
degenerative osteoarthritis appeared as an influential factor in the results (p=0,001). The patients who developed
degenerative osteoarthritis were late more time in coming back to his employment or labor previous activity;
they had a time more delayed from the surgery to the discharge and major total number of labor disabilities and
economic compensations with regard to the patients who did not develop degenerative osteoarthritis, being all
these statistically significant values
PMCTrack: Delivering performance monitoring counter support to the OS scheduler
Hardware performance monitoring counters (PMCs) have proven effective in characterizing application performance. Because PMCs can only be accessed directly at the OS privilege level, kernellevel tools must be developed to enable the end-user and userspace programs to access PMCs. A large body of work has demonstrated that the OS can perform effective runtime optimizations in multicore systems by leveraging performance-counter data. Special attention has been paid to optimizations in the OS scheduler. While existing performance monitoring tools greatly simplify the collection of PMC application data from userspace, they do not provide an architecture-agnostic kernel-level mechanism that is capable of exposing high-level PMC metrics to OS components, such as the scheduler. As a result, the implementation of PMC-based OS scheduling schemes is typically tied to specific processor models. To address this shortcoming we present PMCTrack, a novel tool for the Linux kernel that provides a simple architecture-independent mechanism that makes it possible for the OS scheduler to access per-thread PMC data. Despite being an OSoriented tool, PMCTrack still allows the gathering of monitoring data from userspace, enabling kernel developers to carry out the necessary offline analysis and debugging to assist them during the scheduler design process. In addition, the tool provides both the OS and the user-space PMCTrack components with other insightful metrics available in modern processors and which are not directly exposed as PMCs, such as cache occupancy or energy consumption. This information is also of great value when it comes to analyzing the potential benefits of novel scheduling policies on real systems. In this paper, we analyze different case studies that demonstrate the flexibility, simplicity and powerful features of PMCTrack.Facultad de InformáticaInstituto de Investigación en Informátic
Evaluation of liquid biphasic Granada medium and instant liquid biphasic Granada medium for group B streptococcus detection.
INTRODUCTION: Group B streptococci (GBS) are transmitted from the mother to the newborn. Prevention of neonatal infection is achieved by intrapartum prophylaxis given to mothers colonized with GBS at 35 to 37 weeks of pregnancy.
MATERIALS AND METHODS: Liquid biphasic Granada medium (LB) and instant liquid biphasic Granada medium (ILB) were evaluated for GBS detection. Vaginal swabs obtained from 300 women were inoculated onto LB or ILB, or onto Todd-Hewitt broth and analyzed with the ATB system (comparison method).
RESULTS: Prevalence of GBS was 20% (61/300). LB and Todd-Hewitt with ATB detected GBS in 20% of women, and ILB in 19% of women. No growth was observed at four hours in any of the media studied. At 10 h and 14 h, identification of GBS was possible in 43/300 (14%) and 53/300 (18%) of ILB cultures, respectively, and in 32/300 (11%) and 46/300 (15%) of LB cultures.
CONCLUSION: All the media used are suitable for GBS detection. The majority of GBS were identified in ILB and LB cultures at 10 h and 14 h
The chemical abundance of the very metal rich old Open Clusters NGC 6253 and NGC 6791
In the framework of a project aiming at deriving in a homogeneous way the
properties (age, distance, reddening and detailed chemical abundances) of a
large sample of old open clusters, we present here the metal abundance and the
abundance ratios of light (C, N, O, Na, Mg, Al, Si, Ca, Ti) and heavier (Cr,
Mn, Ni, Ba, Eu) elements in the galactic open clusters NGC 6253 and NGC 6791.
We performed spectrum synthesis of selected lines on high resolution spectra of
four red clump stars in NGC 6253, taken with the UVES and FEROS spectrographs.
We also determined abundances of the same elements for four red clump stars in
NGC 6791, observed with SARG, for which we had derived the atmospheric
parameters and the iron, carbon and oxygen abundances in a previous paper
(Gratton et al. 2006). The average metallicity of NGC 6253 is [Fe/H]=+0.46 (rms
= 0.03 dex, systematic error = 0.08 dex), obtained by extensive spectral
synthesis of Fe lines. This intermediate age cluster closely resembles the old
open cluster NGC 6791, as far as the chemical composition is concerned. C, N, O
do not show any significant abundance scatter; they are underabundant with
respect to the solar values both in NGC 6253 and NGC 6791. We also find no
evident star-to-star scatter in any of the elements measured in both clusters,
with the possible exception of Na in NGC 6791. The two clusters show very
similar abundances, except for Mg, overabundant in NGC 6791 and not in NGC
6253. Both have solar scaled alpha-elements abundances. We have compared our
abundance ratios with literature values for disk giants and dwarfs and bulge
giants, finding a general good agreement with the run of elemental ratios with
[Fe/H] of disk objects.Comment: Accepted for publication on A&
Light bosons and photospheric solutions to the solar abundance problem
It is well known that current spectroscopic determinations of the chemical
composition of the Sun are starkly at odds with the metallicity implied by
helioseismology. We investigate whether the discrepancy may be due to
conversion of photons to a new light boson in the solar photosphere. We examine
the impact of particles with axion-like interactions with the photon on the
inferred photospheric abundances, showing that resonant axion-photon conversion
is not possible in the region of the solar atmosphere in which line-formation
occurs. Although non-resonant conversion in the line-forming regions can in
principle impact derived abundances, constraints from axion-photon conversion
experiments rule out the couplings necessary for these effects to be
detectable. We show that this extends to hidden photons and chameleons (which
would exhibit similar phenomenological behaviour), ruling out known theories of
new light bosons as photospheric solutions to the solar abundance problem.Comment: 11 pages, PDFLaTeX. v2: Major revision. Inclusion of refractive index
effect on photon-ALP conversion strengthens our conclusion that such an
effect cannot explain the solar abundance problem with a coupling allowed by
experimental axion-like particle searches. We now include a discussion of
chameleons and hidden photons, with similar conclusion
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