444 research outputs found
Chlorpromazine for schizophrenia: a Cochrane systematic review of 50 years of randomised controlled trials
BACKGROUND:
Chlorpromazine (CPZ) remains one of the most common drugs used for people with schizophrenia worldwide, and a benchmark against which other treatments can be evaluated. Quantitative reviews are rare; this one evaluates the effects of chlorpromazine in the treatment of schizophrenia in comparison with placebo.
METHODS:
We sought all relevant randomised controlled trials (RCT) comparing chlorpromazine to placebo by electronic and reference searching, and by contacting trial authors and the pharmaceutical industry. Data were extracted from selected trials and, where possible, synthesised and random effects relative risk (RR), the number needed to treat (NNT) and their 95% confidence intervals (CI) calculated.
RESULTS:
Fifty RCTs from 1955–2000 were included with 5276 people randomised to CPZ or placebo. They constitute 2008 person-years spent in trials. Meta-analysis of these trials showed that chlorpromazine promotes a global improvement (n = 1121, 13 RCTs, RR 0.76 CI 0.7 to 0.9, NNT 7 CI 5 to 10), although a considerable placebo response is also seen. People allocated to chlorpromazine tended not to leave trials early in both the short (n = 945, 16 RCTs, RR 0.74 CI 0.5 to 1.1) and medium term (n = 1861, 25 RCTs, RR 0.79 CI 0.6 to 1.1). There were, however, many adverse effects. Chlorpromazine is sedating (n = 1242, 18 RCTs, RR 2.3 CI 1.7 to 3.1, NNH 6 CI 5 to 8), increases a person's chances of experiencing acute movement disorders, Parkinsonism and causes low blood pressure with dizziness and dry mouth.
CONCLUSION:
It is understandable why the World Health Organization (WHO) have endorsed and included chlorpromazine in their list of essential drugs for use in schizophrenia. Low- and middle-income countries may have more complete evidence upon which to base their practice compared with richer nations using recent innovations
Gaps in the cloud cover? Comparing extinction measures in spiral disks
Dust in galaxies can be mapped by either the FIR/sub-mm emission, the optical
or infrared reddening of starlight, or the extinction of a known background
source. We compare two dust extinction measurements for a set of fifteen
sections in thirteen nearby galaxies, to determine the scale of the dusty ISM
responsible for disk opacity: one using stellar reddening and the other a known
background source. In our earlier papers, we presented extinction measurements
of 29 galaxies, based on calibrated counts of distant background objects
identified though foreground disks in HST/WFPC2 images. For the 13 galaxies
that overlap with the Spitzer Infrared Nearby Galaxies Survey (SINGS), we now
compare these results with those obtained from an I-L color map. Our goal is to
determine whether or not a detected distant galaxy indicates a gap in the dusty
ISM, and hence to better understand the nature and geometry of the disk
extinction.
We find that distant galaxies are predominantly in low-extinction sections
marked by the color maps, indicating that their number depends both on the
cloud cover of {\it Spitzer}-resolved dust structures --mostly the spiral
arms--and a diffuse, unresolved underlying disk. We note that our infrared
color map (E[I-L]) underestimates the overall dust presence in these disks
severely, because it implicitly assumes the presence of a dust screen in front
of the stellar distribution.Comment: 22 pages, 2 figures, 3 tables, accepted for publication in A
The Density and Temperature of Molecular Clouds in M33
We have observed the CO J=2-1, J=3-2, and CO J=2-1 lines in a
sample of seven giant molecular clouds in the Local Group spiral galaxy M33.
The CO/CO J=2-1 line ratio is constant across the entire sample,
while the observed CO J=3-2/J=2-1 line ratio has a weak dependence on
the star formation environment of the cloud, with large changes in the line
ratio seen only for clouds in the immediate vicinity of an extremely luminous
HII region. A large velocity gradient analysis indicates that clouds without
HII regions have temperatures of 10-20 K, clouds with HII regions have
temperatures of 15-100 K, and the cloud in the giant HII region has a
temperature of at least 100 K. Interestingly, the giant HII region appears
capable of raising the kinetic temperature of the molecular gas only for clouds
that are quite nearby ( pc). The continuous change of physical
conditions across the observed range of star formation environments suggests
that the unusual physical conditions in the cloud in the giant HII region are
due to post-star formation changes in the molecular gas, rather than intrinsic
properties of the gas related to the formation of the giant HII region.Comment: 14 pages, aastex, 4 postscript figures; accepted for publication in
ApJ; also available at http://www.physics.mcmaster.ca/Wilson_Preprint
Infrared Spectral Energy Distributions of Nearby Galaxies
The Spitzer Infrared Nearby Galaxies Survey (SINGS) is carrying out a
comprehensive multi-wavelength survey on a sample of 75 nearby galaxies. The
1-850um spectral energy distributions are presented using broadband imaging
data from Spitzer, 2MASS, ISO, IRAS, and SCUBA. The infrared colors derived
from the globally-integrated Spitzer data are generally consistent with the
previous generation of models that were developed based on global data for
normal star-forming galaxies, though significant deviations are observed.
Spitzer's excellent sensitivity and resolution also allow a detailed
investigation of the infrared spectral energy distributions for various
locations within the three large, nearby galaxies NGC3031 (M81), NGC5194 (M51),
and NGC7331. Strong correlations exist between the local star formation rate
and the infrared colors f_nu(70um)/f_nu(160um) and f_nu(24um)/f_nu(160um),
suggesting that the 24 and 70um emission are useful tracers of the local star
formation activity level. Preliminary evidence indicates that variations in the
24um emission, and not variations in the emission from polycyclic aromatic
hydrocarbons at 8um, drive the variations in the f_nu(8.0um)/f_nu(24um) colors
within NGC3031, NGC5194, and NGC7331. If the galaxy-to-galaxy variations in
spectral energy distributions seen in our sample are representative of the
range present at high redshift then extrapolations of total infrared
luminosities and star formation rates from the observed 24um flux will be
uncertain at the factor-of-five level (total range). The corresponding
uncertainties using the redshifted 8.0um flux (e.g. observed 24um flux for a
z=2 source) are factors of 10-20. Considerable caution should be used when
interpreting such extrapolated infrared luminosities.Comment: 32 pages including 16 figures; accepted for publication in the
Astrophysical Journa
The Calibration of Mid-Infrared Star Formation Rate Indicators
With the goal of investigating the degree to which the mid-infrared emission
traces the star formation rate (SFR), we analyze Spitzer 8 um and 24 um data of
star-forming regions in a sample of 33 nearby galaxies with available
HST/NICMOS images in the Paschen-alpha (1.8756 um) emission line. The galaxies
are drawn from the Spitzer Infrared Nearby Galaxies Survey (SINGS) sample, and
cover a range of morphologies and a factor ~10 in oxygen abundance. Published
data on local low-metallicity starburst galaxies and Luminous Infrared Galaxies
are also included in the analysis. Both the stellar-continuum-subtracted 8 um
emission and the 24 um emission correlate with the extinction-corrected
Pa-alpha line emission, although neither relationship is linear. Simple models
of stellar populations and dust extinction and emission are able to reproduce
the observed non-linear trend of the 24 um emission versus number of ionizing
photons, including the modest deficiency of 24 um emission in the low
metallicity regions, which results from a combination of decreasing dust
opacity and dust temperature at low luminosities. Conversely, the trend of the
8 um emission as a function of the number of ionizing photons is not well
reproduced by the same models. The 8 um emission is contributed, in larger
measure than the 24 um emission, by dust heated by non-ionizing stellar
populations, in agreement with previous findings. Two SFR calibrations, one
using the 24 um emission and the other using a combination of the 24 um and
H-alpha luminosities (Kennicutt et al. 2007), are presented. No calibration is
presented for the 8 um emission, because of its significant dependence on both
metallicity and environment. The calibrations presented here should be directly
applicable to systems dominated by on-going star formation.Comment: 67 pages, 15 figures, accepted for publication on the Astrophysical
Journal; replacement contains: correction to equation 8; important tweaks to
equation 9; various typos correcte
Mid-Infrared IRS Spectroscopy of NGC 7331: A First Look at the SINGS Legacy
The nearby spiral galaxy NGC 7331 was spectrally mapped from 5-38um using all
modules of Spitzer's IRS spectrograph. A strong new dust emission feature,
presumed due to PAHs, was discovered at 17.1um. The feature's intensity is
nearly half that of the ubiquitous 11.3um band. The 7-14um spectral maps
revealed significant variation in the 7.7 and 11.3um PAH features between the
stellar ring and nucleus. Weak [OIV] 25.9um line emission was found to be
centrally concentrated in the nucleus, with an observed strength over 10% of
the combined neon line flux, indicating an AGN or unusually active massive star
photo-ionization. Two [SIII] lines fix the characteristic electron density in
the HII regions at n_e < ~200 cm^-3. Three detected H_2 rotational lines,
tracing warm molecular gas, together with the observed IR continuum, are
difficult to match with standard PDR models. Either additional PDR heating or
shocks are required to simultaneously match lines and continuum.Comment: 6 pages, 5 figures, accepted for publication in ApJS Spitzer Special
Issu
Warm molecular hydrogen in the Spitzer SINGS galaxy sample
(simplified) Results on the properties of warm H2 in 57 normal galaxies are
derived from H2 rotational transitions, obtained as part of SINGS. This study
extends previous extragalactic surveys of H2, the most abundant constituent of
the molecular ISM, to more common systems (L_FIR = e7 to 6e10 L_sun) of all
morphological and nuclear types. The S(1) transition is securely detected in
the nuclear regions of 86% of SINGS galaxies with stellar masses above 10^9.5
M_sun. The derived column densities of warm H2 (T > ~100 K), even though
averaged over kiloparsec-scale areas, are commensurate with those of resolved
PDRs; the median of the sample is 3e20 cm-2. They amount to between 1% and >30%
of the total H2. The power emitted in the sum of the S(0) to S(2) transitions
is on average 30% of the [SiII] line power, and ~4e-4 of the total infrared
power (TIR) within the same area for star-forming galaxies, which is consistent
with excitation in PDRs. The fact that H2 emission scales tightly with PAH
emission, even though the average radiation field intensity varies by a factor
ten, can also be understood if both tracers originate predominantly in PDRs,
either dense or diffuse. A large fraction of the 25 LINER/Sy targets, however,
strongly depart from the rest of the sample, in having warmer H2 in the excited
states, and an excess of H2 emission with respect to PAHs, TIR and [SiII]. We
propose a threshold in H2 to PAH power ratios, allowing the identification of
low-luminosity AGNs by an excess H2 excitation. A dominant contribution from
shock heating is favored in these objects. Finally, we detect, in nearly half
the star-forming targets, non-equilibrium ortho to para ratios, consistent with
FUV pumping combined with incomplete ortho-para thermalization by collisions,
or possibly non-equilibrium PDR fronts advancing into cold gas.Comment: ApJS, in pres
Bioenergy as climate change mitigation option within a 2 °C target—uncertainties and temporal challenges of bioenergy systems
Bioenergy is given an important role in reaching national and international climate change targets. However, uncertainties relating to emission reductions and the timeframe for these reductions are increasingly recognised as challenges whether bioenergy can deliver the required reductions. This paper discusses and highlights the challenges and the importance of the real greenhouse gas (GHG) reduction potential of bioenergy systems and its relevance for a global 450 ppm CO2e stabilisation target in terms of uncertainties and temporal aspects. The authors aim to raise awareness and emphasise the need for dynamic and consequential approaches for the evaluation of climate change impacts of bioenergy systems to capture the complexity and challenges of their real emission reduction potential within a 2 °C target. This review does not present new research results. This paper shows the variety of challenges and complexity of the problem of achieving real GHG emission reductions from bioenergy systems. By reflecting on current evaluation methods of emissions and impacts from bioenergy systems, this review points out that a rethinking and going beyond static approaches is required, considering each bioenergy systems according to its own characteristics, context and feedbacks. With the development of knowledge and continuously changing systems, policies should be designed in a way that they provide a balance between flexibility to adapt to new information and planning security for investors. These will then allow considering if a bioenergy system will deliver the required emission saving in the appropriate timeframe or not
The Nature of Infrared Emission in the Local Group Dwarf Galaxy NGC 6822 As Revealed by Spitzer
We present Spitzer imaging of the metal-deficient (Z ~30% Z_sun) Local Group
dwarf galaxy NGC 6822. On spatial scales of ~130 pc, we study the nature of IR,
H alpha, HI, and radio continuum emission. Nebular emission strength correlates
with IR surface brightness; however, roughly half of the IR emission is
associated with diffuse regions not luminous at H alpha (as found in previous
studies). The global ratio of dust to HI gas in the ISM, while uncertain at the
factor of ~2 level, is ~25 times lower than the global values derived for
spiral galaxies using similar modeling techniques; localized ratios of dust to
HI gas are about a factor of five higher than the global value in NGC 6822.
There are strong variations (factors of ~10) in the relative ratios of H alpha
and IR flux throughout the central disk; the low dust content of NGC 6822 is
likely responsible for the different H alpha/IR ratios compared to those found
in more metal-rich environments. The H alpha and IR emission is associated with
high-column density (> ~1E21 cm^-2) neutral gas. Increases in IR surface
brightness appear to be affected by both increased radiation field strength and
increased local gas density. Individual regions and the galaxy as a whole fall
within the observed scatter of recent high-resolution studies of the radio-far
IR correlation in nearby spiral galaxies; this is likely the result of depleted
radio and far-IR emission strengths in the ISM of this dwarf galaxy.Comment: ApJ, in press; please retrieve full-resolution version from
http://www.astro.wesleyan.edu/~cannon/pubs.htm
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