16,043 research outputs found
High-Resolution 4.7 Micron Keck/NIRSPEC Spectra of Protostars. II. Detection of the ^(13)CO Isotope in Icy Grain Mantles
The high-resolution (R = 25,000) infrared M-band spectrum of the massive protostar NGC 7538 IRS 9 shows a narrow absorption feature at 4.779 ÎŒm (2092.3 cm^(-1)) that we attribute to the vibrational stretching mode of the ^(13)CO isotope in pure CO icy grain mantles. This is the first detection of ^(13)CO in icy grain mantles in the interstellar medium. The ^(13)CO band is a factor of 2.3 narrower than the apolar component of the ^(12)CO band. With this in mind, we discuss the mechanisms that broaden solid-state absorption bands. It is shown that ellipsoidally shaped pure CO grains fit the bands of both isotopes at the same time. Slightly worse but still reasonable fits are also obtained by CO embedded in N_2-rich ices and thermally processed O_2-rich ices. In addition, we report new insights into the nature and evolution of interstellar CO ices by comparing the very high resolution multicomponent solid ^(12)CO spectrum of NGC 7538 IRS 9 with that of the previously studied low-mass source L1489 IRS. The narrow absorption of apolar CO ices is present in both spectra but much stronger in NGC 7538 IRS 9. It is superposed on a smooth broad absorption feature well fitted by a combination of CO_2 and H_2O-rich laboratory CO ices. The abundances of the latter two ices, scaled to the total H_2O ice column, are the same in both sources. We thus suggest that thermal processing manifests itself as evaporation of apolar ices only and not the formation of CO_2 or polar ices. Finally, the decomposition of the ^(12)CO band is used to derive the ^(12)CO/^(13)CO abundance ratio in apolar ices. A ratio of ^(12)CO/^(13)CO = 71 ± 15 (3 Ï) is deduced, in good agreement with gas-phase CO studies (~77) and the solid ^(12)CO_2/^(13)CO_2 ratio of 80 ± 11 found in the same line of sight. The implications for the chemical path along which CO_2 is formed are discussed
Knowledge gaps in host-parasite interaction preclude accurate assessment of meat-borne exposure to Toxoplasma gondii
Seeing More than Orange: Organizational Respect and Positive Identity Transformation in a Prison Context
This paper develops grounded theory on how receiving respect at work enables individuals to engage in positive identity transformation and the resulting personal and work-related outcomes. A company that employs inmates at a state prison to perform professional business-to-business marketing services provided a unique context for data collection. Our data indicate that inmates experienced respect in two distinct ways, generalized and particularized, which initiated an identity decoupling process that allowed them to distinguish between their inmate identity and their desired future selves and to construct transitional identities that facilitated positive change. The social context of the organization provided opportunities for personal and social identities to be claimed, respected, and granted, producing social validation and enabling individuals to feel secure in their transitional identities. We find that security in personal identities produces primarily performance-related outcomes, whereas security in the company identity produces primarily well-being-related outcomes. Further, these two types of security together foster an integration of seemingly incompatible identitiesââidentity holismââas employees progress toward becoming their desired selves. Our work suggests that organizations can play a generative role in improving the lives of their members through respect-based processes
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The Impact of Covid-19 on Future Higher-Age Mortality
Covid-19 has predominantly affected mortality at high ages. It kills by inflaming and clogging the air sacs in the lungs, depriving the body of oxygen â inducing hypoxia â which closes down essential organs, in particular the heart, kidneys and liver, and causes blood clots (which can lead to stroke or pulmonary embolism) and neurological malfunction.
Evidence from different countries points to the fact that people who die from Covid-19 are often, but not always, much less healthy than the average for their age group. This is true for England & Wales â the two countries we focus on in this study. The implication is that the years of life lost through early death are less than the average for each age group, with how much less being a source of considerable debate. We argue that many of those who die from coronavirus would have died anyway in the relatively near future due to their existing frailties or co-morbidities. We demonstrate how to capture this link to poorer-than-average health using a model in which individual deaths are âacceleratedâ ahead of schedule due to Covid-19. The model structure and its parameterization build on the observation that Covid-19 mortality by age is approximately proportional to all-cause mortality. This, in combination with current predictions of total deaths, results in the important conclusion that, everything else being equal, the impact of Covid-19 on the mortality rates of the surviving population will be very modest. Specifically, the degree of anti-selection is likely to be very small, since the life expectancy of survivors does not increase by a significant amount over pre-pandemic levels.
We also analyze the degree to which Covid-19 mortality varies with socio-economic status. Headline statistics suggest that the most deprived groups have been disproportionately affected by Covid-19. However, once we control for regional differences in mortality rates, Covid-19 deaths in both the most and least deprived groups are also proportional to the all-cause mortality of these groups. However, the groups in between have approximately 10-15% lower Covid-19 deaths compared with their all-cause mortality.
We argue that useful lessons about the potential pattern of accelerated deaths from Covid-19 can be drawn from examining deaths from respiratory diseases, especially at different age ranges. We also argue that it is possible to draw useful lessons about volatility spikes in Covid-19 deaths from examining past seasonal flu epidemics. However, there is an important difference. Whereas the spikes in seasonal flu increase with age, our finding that Covid-19 death rates are approximately proportional to all-cause mortality suggests that any spike in Covid-19 mortality in percentage terms would be similar across all age ranges.
Finally, we discuss some of the indirect consequences for future mortality of the pandemic and the âlockdownâ measures governments have imposed to contain it. For example, there is evidence that some surviving patients at all ages who needed intensive care could end up with a new impairment, such as organ damage, which will reduce their life expectancy. There is also evidence that many people in lockdown did not seek a timely medical assessment for a potential new illness, such as cancer, or deferred seeking treatment for an existing serious illness, with the consequence that non-Covid-19-related mortality rates could increase in future. Self-isolation during lockdown has contributed to an increase in alcohol and drug consumption by some people which might, in turn, reduce their life expectancy. If another consequence of the pandemic is a recession and/or an acceleration in job automation, resulting in long-term unemployment, then this could lead to so-called âdeaths of despairâ in future. Other people, by contrast, might permanently change their social behaviour or seek treatments that delay the impact or onset of age-related diseases, one of the primary factors that make people more susceptible to the virus â both of which could have the effect of increasing their life expectancy. It is, however, too early to quantify these possibilities, although it is conceivable that these indirect consequences could have a bigger impact on future average life expectancy than the direct consequences measured by the accelerated deaths model
Water production in comet 81P/Wild 2 as determined by Herschel/HIFI
The high spectral resolution and sensitivity of Herschel/HIFI allows for the detection of multiple rotational water lines and accurate determinations
of water production rates in comets. In this Letter we present HIFI observations of the fundamental 1_(10)â1_(01) (557 GHz) ortho and 1_(11)â0_(00)
(1113 GHz) para rotational transitions of water in comet 81P/Wild 2 acquired in February 2010. We mapped the extent of the water line emission
with five point scans. Line profiles are computed using excitation models which include excitation by collisions with electrons and neutrals and
solar infrared radiation. We derive a mean water production rate of 1.0 Ă 10^(28) molecules s^(â1) at a heliocentric distance of 1.61 AU about 20 days
before perihelion, in agreement with production rates measured from the ground using observations of the 18-cm OH lines. Furthermore, we
constrain the electron density profile and gas kinetic temperature, and estimate the coma expansion velocity by fitting the water line shapes
HIFI observations of water in the atmosphere of comet C/2008 Q3 (Garradd)
High-resolution far-infrared and sub-millimetre spectroscopy of water lines is an important tool to understand the physical and chemical properties of cometary atmospheres.We present observations of several rotational ortho- and para-water transitions in comet C/2008 Q3 (Garradd) performed with HIFI on Herschel. These observations have provided the first detection of the 2_(12)â1_(01) (1669 GHz) ortho and 1_(11)â0_(00) (1113 GHz) para transitions of water in a cometary spectrum. In addition, the ground-state transition 1_(10)â1_(01) at 557 GHz is detected and mapped. By detecting several water lines quasi-simultaneously and mapping their emission we can constrain the excitation parameters in the coma. Synthetic line profiles are computed using excitation models which include excitation by collisions, solar infrared radiation, and radiation trapping. We obtain the gas kinetic temperature, constrain the electron density profile, and estimate the coma expansion velocity by analyzing the map and line shapes. We derive water production rates of 1.7â2.8 Ă 10^(28) s^(â1) over the range r_h = 1.83â1.85 AU
Dust, Ice, and Gas In Time (DIGIT) Herschel program first results: A full PACS-SED scan of the gas line emission in protostar DK Chamaeleontis
Aims. We aim to study the composition and energetics of the circumstellar material of DK Cha, an intermediate-mass star in transition from an
embedded configuration to a star plus disk stage, during this pivotal stage of its evolution.
Methods. Using the range scan mode of PACS on the Herschel Space Observatory, we obtained a spectrum of DK Cha from 55 to 210 ÎŒm as part
of the DIGIT key program.
Results. Almost 50 molecular and atomic lines were detected, many more than the 7 lines detected in ISO-LWS. Nearly the entire ladder of CO
from J = 14â13 to 38â37 (E_u/k = 4080 K), water from levels as excited as J_(Kâ1 K+1) = 7_(07) (E_u/k = 843 K), and OH lines up to E_u/k = 290 K were
detected.
Conclusions. The continuum emission in our PACS SED scan matches the flux expected by a model consisting of a star, a surrounding disk of
0.03 M_â, and an envelope of a similar mass, supporting the suggestion that the object is emerging from its main accretion stage. Molecular, atomic,
and ionic emission lines in the far-infrared reveal the outflowâs influence on the envelope. The inferred hot gas may be photon-heated, but some
emission may be caused by C-shocks in the walls of the outflow cavity
Search for interstellar methoxyacetonitrile and cyanoethanol: insights into coupling of cyano- to methanol and ammonia chemistry
As part of an effort to study gas-grain chemical models in star-forming regions as they relate to molecules
containing cyanide (âCâĄN) groups, we present here a search for the molecules 2-cyanoethanol (OHCH_2CH_2CN) and methoxyacetonitrile (CH_3OCH_2CN) in the galactic center region SgrB2. These species are structural isomers
of each other and are targeted to investigate the cross-coupling of pathways emanating from the photolysis products
of methanol and ammonia with pathways involving cyano-containing molecules. Methanol and ammonia ices are two of the main repositories of the elements C, O, and N in cold clouds and understanding their link to cyanide chemistry could give important insights into prebiotic molecular evolution. Neither species was positively detected, but the upper limits we determined allow comparison to the general patterns gleaned from chemical models. Our results indicate the need for an expansion of the model networks to better deal with cyanochemistry, in particular with respect to pathways including products of methanol photolysis. In addition to these results, the two main observational routes for detecting new interstellar molecules are discussed. One route is by decreasing detection limits at millimeter wavelength through spatial filtering with interferometric studies at the Atacama Large Millimeter Array (ALMA), and the second is by searching for intense torsional states at THz frequencies using the Herschel Space Observatory. 2-cyanoethanol and methoxyacetonitrile would both be good test beds for exploring the capabilities of ALMA and Herschel in the study of complex interstellar chemistry
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