49 research outputs found
Influence of grain growth on CO2 ice spectroscopic profiles : Modelling for dense cores and disks
Interstellar dust grain growth in dense clouds and protoplanetary disks, even
moderate, affects the observed interstellar ice profiles as soon as a
significant fraction of dust grains is in the size range close to the wave
vector at the considered wavelength. The continuum baseline correction made
prior to analysing ice profiles influences the subsequent analysis and hence
the estimated ice composition, typically obtained by band fitting using thin
film ice mixture spectra. We model the effect of grain growth on ice mantle
spectroscopic profiles, focusing on CO2 to see how it can affect interstellar
ice mantle spectral analysis and interpretation. Using the Discrete Dipole
Approximation for Scattering and Absorption of Light, the mass absorption
coefficients of distributions of grains composed of ellipsoidal silicate cores
with water and carbon dioxide ice mantles are calculated. A few other ice
mantle compositions are also calculated. We explore the size distribution
evolution from dense clouds to simulate the first steps of grain growth up to
three microns in size. The results are injected into RADMC-3D full scattering
radiative transfer models of spherical clouds and protoplanetary disk templates
to retrieve observable spectral energy distributions. We focus on calculated
profile of the CO2 antisymmetric stretching mode ice band profile at 4.27
microns, a meaningful indicator of grain growth. The observed profiles toward
dense cores with the Infrared space observatory and Akari satellites already
showed profiles possibly indicative of moderate grain growth.The observation of
protoplanetary disks at high inclination with the JWST should present distorted
profiles that will put constraints on the extent of dust growth. The more
evolved the dust size distribution, the more the extraction of the ice mantle
composition will require both understanding and taking into account grain
growth.Comment: 19 pages, 16 figure
Tigecycline is efficacious in the treatment of complicated intra-abdominal infections
Background
Empiric treatment of complicated intra-abdominal infections (cIAI) represents a clinical challenge because of the diverse bacteriology and the emergence of bacterial resistance. The efficacy and safety of tigecycline (TGC), a first-in-class, expanded broad-spectrum glycylcycline antibiotic, were compared with imipenem/cilastatin (IMI/CIS) in patients with cIAI.
Methods
In this prospective, double-blind, phase 3, multinational trial, patients were randomly assigned to intravenous (IV) TGC (100 mg initial dose, then 50 mg every 12 h) or IV IMI/CIS (500/500 mg every 6 h) for 5–14 days. Clinical response was assessed at the test-of-cure (TOC) visit (14–35 days after therapy) for microbiologically evaluable (ME) and microbiologically modified intent-to-treat (m-mITT) populations (co-primary efficacy endpoint populations in which cure/failure response rates were determined).
Results
Of 817 mITT patients (i.e., received ≥ 1 dose of study drug), 641 (78%) comprised the m-mITT cohort (322 TGC, 319 IMI/CIS) and 523 (64%) were ME (266 TGC, 256 IMI/CIS). Patients were predominantly white (88%) and male (59%) with a mean age of 49 years. The primary diagnoses for the mITT group were complicated appendicitis (41%), cholecystitis (22%), and intra-abdominal abscess (11%). For the ME population, clinical cure rates at TOC were 91.3% (242/265) for TGC versus 89.9% (232/258) for IMI/CIS (95% CI −4.0, 6.8; P < 0.001). Corresponding clinical cure rates within the m-mITT population were 86.6% (279/322) for TGC versus 84.6% (270/319) for IMI/CIS (95% CI −3.7, 7.5; P < 0.001 for noninferiority TGC versus IMI/CIS). The most commonly reported adverse events for TGC and IMI/CIS were nausea (17.6% TGC versus 13.3% IMI/CIS; P = 0.100) and vomiting (12.6% TGC versus 9.2% IMI/CIS; P = 0.144).
Conclusions
TGC is efficacious in the treatment of patients with cIAIs and TGC met per the protocol-specified statistical criteria for noninferiority to the comparator, IMI/CIS
Which individuals are at increased risk of pneumococcal disease and why? Impact of COPD, asthma, smoking, diabetes, and/or chronic heart disease on community-acquired pneumonia and invasive pneumococcal disease
Pneumococcal disease (including community-acquired pneumonia and invasive pneumococcal disease) poses a burden to the community all year round, especially in those with chronic underlying conditions. Individuals with COPD, asthma or who smoke, and those with chronic heart disease or diabetes mellitus have been shown to be at increased risk of pneumococcal disease compared with those without these risk factors. These conditions, and smoking, can also adversely affect patient outcomes, including short-term and long-term mortality rates, following pneumonia. Community-acquired pneumonia, and in particular pneumococcal pneumonia, is associated with a significant economic burden, especially in those who are hospitalised, and also has an impact on a patient's quality of life. Therefore, physicians should target individuals with COPD, asthma, heart disease or diabetes mellitus, and those who smoke, for pneumococcal vaccination at the earliest opportunity at any time of the year
A retrospective study of hospitalized pneumonia in two Polish counties (2006–2008)
WSTĘP: Dane dotyczące etiologii zapaleń płuc w Polsce są skąpe, a wyszczepialność szczepionką pneumokokową wśród osób w najmłodszej i najstarszej grupie wiekowej — nieznaczna. Celem prezentowanego badania była ocena leczonego szpitalnie zapalenia płuc we wszystkich grupach wiekowych w dwóch powiatach Polski.MATERIAŁ I METODY: W badaniu wykorzystano dane zawarte w elektronicznych szpitalnych bazach danych, dotyczące mieszkańców powiatów, hospitalizowanych w Szpitalach Powiatowych w Chrzanowie i Inowrocławiu w latach 2006–2008, z rozpoznaniem zapalenia płuc. Uzyskane wyniki: częstość hospitalizacji na 1000 osób, współczynnik śmiertelności w trakcie pobytu w szpitalu na 100 osób, mediana długości hospializacji, zgrupowano według roku przyjęcia, płci i wieku.WYNIKI: W Szpitalu Powiatowym w Chrzanowie stwierdzono 1444, a w Inowrocławiu 2956 przypadków hospitalizacji z niezależnymi epizodami zapalenia płuc. Częstość hospitalizacji wyniosła 3,76 (95% przedział ufności [CI]: 3,57;3,96) i 5,99 (95% CI: 5,77; 6,21) na 1000, odpowiednio dla powiatów chrzanowskiego i inowrocławskiego. W całej badanej grupie najwyższą częstość hospitalizacji obserwowano w grupie 0–4 lat (30,77 [95% CI: 29,06; 32,55]) oraz ≥ 75 lat (25,39 [95% CI: 24,01; 26,83]). Współczynnik śmiertelności w szpitalu w obu badanych ośrodkach wzrastał wraz z wiekiem. Mediana długości pobytu w szpitalu wyniosła 8 dni.WNIOSKI: Liczba hospitalizacji z powodu zapalenia płuc była znacząca, szczególnie w najmłodszej i najstarszej grupie wiekowej. Przyszłe działania opieki zdrowotnej skierowane do tych grup wiekowych mogą wpłynąć na zapadalność na zapalenie płuc oraz poprawić wyniki leczenia.INTRODUCTION: In Poland, multi-cause pneumonia is not well characterized, and there is limited pneumococcal vaccination in the youngest and oldest age groups. The goal of this study was to assess hospitalized pneumonia across all age groups in two Polish counties.MATERIAL AND METHODS: Using electronic administrative databases, cases were identified as county residents hospitalized at Chrzanów and Inowrocław County Hospitals from 2006–2008, assigned a diagnosis of pneumonia. Calculations by admission year, sex, and age category were: hospitalization rates per 1000 persons; in-hospital mortality rates per 100 persons; and median length of stay (LOS).RESULTS: There were 1444 and 2956 hospitalizations for new episodes of pneumonia with rates of 3.76 (95% confidence interval [CI] 3.57–3.96) and 5.99 (95% CI 5.77–6.21) per 1000 persons in Chrzanów and Inowrocław counties, respectively. In combined data, the highest hospitalization rate was among patients aged 0–4 years (30.77; 95% CI 29.06–32.55) followed by those aged ≥ 75 years (25.39; 95% CI 24.01–26.83). In-hospital mortality rates increased with age at both sites. The median LOS was 8 days.CONCLUSIONS: Pneumonia hospitalizations were substantial, especially for the youngest and oldest age groups. Future public health interventions aimed at these age groups might improve disease outlook
PDRs4All III: JWST's NIR spectroscopic view of the Orion Bar
(Abridged) We investigate the impact of radiative feedback from massive stars
on their natal cloud and focus on the transition from the HII region to the
atomic PDR (crossing the ionisation front (IF)), and the subsequent transition
to the molecular PDR (crossing the dissociation front (DF)). We use
high-resolution near-IR integral field spectroscopic data from NIRSpec on JWST
to observe the Orion Bar PDR as part of the PDRs4All JWST Early Release Science
Program. The NIRSpec data reveal a forest of lines including, but not limited
to, HeI, HI, and CI recombination lines, ionic lines, OI and NI fluorescence
lines, Aromatic Infrared Bands (AIBs including aromatic CH, aliphatic CH, and
their CD counterparts), CO2 ice, pure rotational and ro-vibrational lines from
H2, and ro-vibrational lines HD, CO, and CH+, most of them detected for the
first time towards a PDR. Their spatial distribution resolves the H and He
ionisation structure in the Huygens region, gives insight into the geometry of
the Bar, and confirms the large-scale stratification of PDRs. We observe
numerous smaller scale structures whose typical size decreases with distance
from Ori C and IR lines from CI, if solely arising from radiative recombination
and cascade, reveal very high gas temperatures consistent with the hot
irradiated surface of small-scale dense clumps deep inside the PDR. The H2
lines reveal multiple, prominent filaments which exhibit different
characteristics. This leaves the impression of a "terraced" transition from the
predominantly atomic surface region to the CO-rich molecular zone deeper in.
This study showcases the discovery space created by JWST to further our
understanding of the impact radiation from young stars has on their natal
molecular cloud and proto-planetary disk, which touches on star- and planet
formation as well as galaxy evolution.Comment: 52 pages, 30 figures, submitted to A&
A far-ultraviolet-driven photoevaporation flow observed in a protoplanetary disk
Most low-mass stars form in stellar clusters that also contain massive stars,
which are sources of far-ultraviolet (FUV) radiation. Theoretical models
predict that this FUV radiation produces photo-dissociation regions (PDRs) on
the surfaces of protoplanetary disks around low-mass stars, impacting planet
formation within the disks. We report JWST and Atacama Large Millimetere Array
observations of a FUV-irradiated protoplanetary disk in the Orion Nebula.
Emission lines are detected from the PDR; modelling their kinematics and
excitation allows us to constrain the physical conditions within the gas. We
quantify the mass-loss rate induced by the FUV irradiation, finding it is
sufficient to remove gas from the disk in less than a million years. This is
rapid enough to affect giant planet formation in the disk
PDRs4All II: JWST's NIR and MIR imaging view of the Orion Nebula
The JWST has captured the most detailed and sharpest infrared images ever
taken of the inner region of the Orion Nebula, the nearest massive star
formation region, and a prototypical highly irradiated dense photo-dissociation
region (PDR). We investigate the fundamental interaction of far-ultraviolet
photons with molecular clouds. The transitions across the ionization front
(IF), dissociation front (DF), and the molecular cloud are studied at
high-angular resolution. These transitions are relevant to understanding the
effects of radiative feedback from massive stars and the dominant physical and
chemical processes that lead to the IR emission that JWST will detect in many
Galactic and extragalactic environments. Due to the proximity of the Orion
Nebula and the unprecedented angular resolution of JWST, these data reveal that
the molecular cloud borders are hyper structured at small angular scales of
0.1-1" (0.0002-0.002 pc or 40-400 au at 414 pc). A diverse set of features are
observed such as ridges, waves, globules and photoevaporated protoplanetary
disks. At the PDR atomic to molecular transition, several bright features are
detected that are associated with the highly irradiated surroundings of the
dense molecular condensations and embedded young star. Toward the Orion Bar
PDR, a highly sculpted interface is detected with sharp edges and density
increases near the IF and DF. This was predicted by previous modeling studies,
but the fronts were unresolved in most tracers. A complex, structured, and
folded DF surface was traced by the H2 lines. This dataset was used to revisit
the commonly adopted 2D PDR structure of the Orion Bar. JWST provides us with a
complete view of the PDR, all the way from the PDR edge to the substructured
dense region, and this allowed us to determine, in detail, where the emission
of the atomic and molecular lines, aromatic bands, and dust originate
Rotationally resolved IR spectroscopy of hexamethylenetetramine (HMT) C<sub>6</sub>N<sub>4</sub>H<sub>12</sub>
International audienceHexamethylenetetramine (HMT) appears to be a potential constituent of several objects in space, including comets or Titan's atmosphere and, as an organic residue of ice irradiation in the laboratory, it may be present in the interstellar medium. Aims. We performed a laboratory study of rotationally resolved intense IR bands of HMT to provide accurate line positions and synthetic spectra to be used for potential astronomical detections. Methods. We used synchrotron-based high-resolution Fourier transform infrared spectroscopy to record the experimental data. A formalism and programs dedicated to the assignment, analysis, and simulation of absorption spectra of tetrahedral molecules were used to exploit the spectra. Results. Infrared spectra of gas phase HMT were recorded and accurate wavenumbers and molecular parameters for four intense bands located in the 1000-1500 cm−1 spectral range suitable for astronomical searches were derived