615 research outputs found
Bound non-locality and activation
We investigate non-locality distillation using measures of non-locality based
on the Elitzur-Popescu-Rohrlich decomposition. For a certain number of copies
of a given non-local correlation, we define two quantities of interest: (i) the
non-local cost, and (ii) the distillable non-locality. We find that there exist
correlations whose distillable non-locality is strictly smaller than their
non-local cost. Thus non-locality displays a form of irreversibility which we
term bound non-locality. Finally we show that non-local distillability can be
activated.Comment: 4 pages, 1 figur
Productivity and Profitability of a Cotton-based Production System under Organic and Conventional Management in India
The debate on the relative benefits of conventional and organic farming systems is more topical than ever. The achievements of conventional high-input agriculture were largely brought about at the cost of deteriorating soil fertility; furthermore, they were based to a large extent on fossil fuels. Developing more sustainable farming practices on a large scale is of utmost importance. However, information about the performance of agricultural production systems under organic and conventional management in tropical and subtropical regions is largely lacking. This study aimed to assess agronomic and economic data from a long-term farming systems comparison trial under semi-arid conditions in central India.
Four two-year crop rotations comprising cotton-soybean-wheat under biodynamic, organic and conventional management were investigated, including one conventional system with and one without transgenic Bt cotton, between 2007 and 2010.
Results showed 13% lower yields in organic compared to conventional systems. Yields in cotton, soybean and wheat were on average 14 %, 7% and 15% lower, respectively. However, production costs of organic systems were on average 32% lower than those of conventional systems, which led to similar gross margins in all systems.
To our knowledge, this is the first long-term field trial comparing the agronomic and economic performance of organic, conventional and conventional+Bt cotton-based farming systems. The results of our study suggest that organic farming is a promising alternative to conventional farming in cotton-based production systems in central India. The less capital intensive nature of organic systems may be particularly interesting for smallholder farmers as it decreases dependence on loans for farm inputs. Therefore, our findings have the potential to be useful for decision-making and in turn may lead to a redirection of agricultural policies
Quasar Evolution and the Baldwin Effect in the Large Bright Quasar Survey
From a large homogeneous sample of optical/UV emission line measurements for
993 quasars from the Large Bright Quasar Survey (LBQS), we study correlations
between emission line equivalent width and both restframe ultraviolet
luminosity (i.e., the Baldwin Effect) and redshift. Our semi-automated spectral
fitting accounts for absorption lines, fits blended iron emission, and provides
upper limits to weak emission lines. Use of a single large, well-defined sample
and consistent emission line measurements allows us to sensitively detect many
correlations, most of which have been previously noted. A new finding is a
significant Baldwin Effect in UV iron emission. Further analysis reveals that
the primary correlation of iron emission strength is probably with redshift,
implying an evolutionary rather than a luminosity effect. We show that for most
emission lines with a significant Baldwin Effect, and for some without,
evolution dominates over luminosity effects. This may reflect evolution in
abundances, in cloud covering factors, or overall cloud conditions such as
density and ionization. We find that in our sample, a putative correlation
between Baldwin Effect slope and the ionization potential is not significant.
Uniform measurements of other large quasar samples will extend the luminosity
and redshift range of such spectral studies and provide even stronger tests of
spectral evolution.Comment: 16 pages, Latex, emulateapj style, including 3 tables and 6 figures.
Accepted April 02, 2001 for publication in ApJ Main Journal. See also
http://hea-www.harvard.edu/~pgreen/Papers.htm
Taxon-specific multiplex-PCR for quick, easy, and accurate identification of encyrtid and aphelinid parasitoid species attacking soft scale insects in California citrus groves
Citricola scale, Coccus pseudomagnoliarum Kuwana (Hemiptera: Coccidae), is a serious pest of citrus in California's San Joaquin Valley, but not in southern California where a complex of Metaphycus spp. Mercet (Hymenoptera: Encyrtidae) suppress it. This has created interest in using these (and other Metaphycus) species for biological control in the San Joaquin Valley. A critical step in assessing an organism's potential for biological control is the ability to accurately identify it. For Metaphycus spp., this currently requires slide mounted adult specimens and expert taxonomic knowledge. We present a simple, quick and accurate method to identify any life stage of the ten major parasitoids of soft scales in California citrus, based on amplification of ribosomal DNA, using the polymerase chain reaction (PCR). Three multiplex-PCR protocols amplify products of taxon-specific sizes, allowing direct diagnosis of taxa accommodated by the PCR, and reducing identification time to a fraction of that of existing methods
Measuring the Average Evolution of Luminous Galaxies at z<3: The Rest-frame Optical Luminosity Density, Spectral Energy Distribution, and Stellar Mass Density
(Abridged) We present the evolution of the volume averaged properties of the
rest-frame optically luminous galaxy population to z~3, determined from four
disjoint deep fields with optical to near-infrared wavelength coverage. We
select galaxies above a rest-frame V-band luminosity of 3x10^10 Lsol and
characterize their rest-frame UV through optical properties via the mean
spectral energy distribution (SED). To measure evolution we apply the same
selection criteria to a sample of galaxies from the Sloan Digital Sky Survey
and COMBO-17. The mean rest-frame 2200Ang through V-band SED becomes steadily
bluer with increasing redshift but at z<3 the mean SED falls within the range
defined by ``normal'' galaxies in the nearby Universe. We measure stellar
mass-to-light ratios (Mstar/L) by fitting models to the rest-frame UV-optical
SEDs and derive the stellar mass density. The stellar mass density in luminous
galaxies has increased by a factor of 3.5-7.9 from z=3 to z=0.1, including
field-to-field variance uncertainties. After correcting to total, the measured
mass densities at z<2 lie below the integral of the star formation rate (SFR)
density as a function of redshift as derived from UV selected samples. This may
indicate a systematic error in the mass densities or SFR(z) estimates. We find
large discrepancies between recent model predictions for the evolution of the
mass density and our results, even when our observational selection is applied
to the models. Finally we determine that Distant Red Galaxies (selected to have
J_s - K_s>2.3) in our LV selected samples contribute 30% and 64% of the stellar
mass budget at z~2 and z~ 2.8 respectively. These galaxies are largely absent
from UV surveys and this result highlights the need for mass selection of high
redshift galaxies.Comment: Accepted for publication in the Astrophysical Journal, 24 pages, 16
figure
Direct Measurements of the Stellar Continua and Balmer/4000 Angstrom Breaks of Red z>2 Galaxies: Redshifts and Improved Constraints on Stellar Populations
We use near-infrared (NIR) spectroscopy obtained with GNIRS on Gemini,
NIRSPEC on KECK, and ISAAC on the VLT to study the rest-frame optical continua
of three `Distant Red Galaxies' (having Js - Ks > 2.3) at z>2. All three galaxy
spectra show the Balmer/4000 Angstrom break in the rest-frame optical. The
spectra allow us to determine spectroscopic redshifts from the continuum with
an estimated accuracy dz/(1+z) ~ 0.001-0.04. These redshifts agree well with
the emission line redshifts for the 2 galaxies with Halpha emission. This
technique is particularly important for galaxies that are faint in the
rest-frame UV, as they are underrepresented in high redshift samples selected
in optical surveys and are too faint for optical spectroscopy. Furthermore, we
use the break, continuum shape, and equivalent width of Halpha together with
evolutionary synthesis models to constrain the age, star formation timescale,
dust content, stellar mass and star formation rate of the galaxies. Inclusion
of the NIR spectra in the stellar population fits greatly reduces the range of
possible solutions for stellar population properties. We find that the stellar
populations differ greatly among the three galaxies, ranging from a young dusty
starburst with a small break and strong emission lines to an evolved galaxy
with a strong break and no detected line emission. The dusty starburst galaxy
has an age of 0.3 Gyr and a stellar mass of 1*10^11 Msun. The spectra of the
two most evolved galaxies imply ages of 1.3-1.4 Gyr and stellar masses of
4*10^11 Msun. The large range of properties seen in these galaxies strengthens
our previous much more uncertain results from broadband photometry. Larger
samples are required to determine the relative frequency of dusty starbursts
and (nearly) passively evolving galaxies at z~2.5.Comment: Accepted for publication in the Astrophysical Journal. 12 pages, 6
figure
The Color Magnitude Distribution of Field Galaxies to z~3: the evolution and modeling of the blue sequence
Using deep NIR VLT/ISAAC and optical HST/WFPC2 imaging in the fields of the
HDFS and MS1054-03, we study the rest-frame UV-to-optical colors and magnitudes
of galaxies to z~3. While there is no evidence for a red sequence at z~3, there
does appear to be a well-defined color-magnitude relation (CMR) for blue
galaxies at all redshifts, with more luminous galaxies having redder U-V
colors. The slope of the blue CMR is independent of redshift d(U-V)/dMV = -0.09
(0.01) and can be explained by a correlation of dust-reddening with luminosity.
The average color at fixed luminosity reddens strongly \Delta(U-V) = 0.75 from
z~3 to z=0, much of which can be attributed to aging of the stars. The color
scatter of the blue sequence is relatively small sigma(U-V) = 0.25 (0.03) and
constant to z~3, but notably asymmetrical with a sharp blue ridge and a wing
towards redder colors. We explore sets of star formation histories to study the
constraints placed by the shape of the scatter at z=2-3. One particular set of
models, episodic star formation, reproduces the detailed properties very well.
For a two-state model with high and low star formation, the duty cycle is
constrained to be > 40% and the contrast between the states must be a factor >
5 (or a scatter in log(SFR) of > 0.35 dex around the mean). However, episodic
models do not explain the observed tail of very red galaxies, primarily Distant
Red Galaxies (DRGs), which may have ceased star formation altogether or are
more heavily obscured. Finally, the relative number density of red, luminous MV
< -20.5 galaxies increases by a factor of ~ 6 from z = 2.7 to z = 0.5, as does
their contribution to the total rest-frame V-band luminosity density. We are
likely viewing the progressive formation of red, passively evolving galaxies.Comment: 29 pages, 24 figures, in emulateapj style. Abstract is abridged. Some
postscript figures are compressed. accepted for publication in ApJ (scheduled
for August 20, 2007, v665n 2 issue
Development of stabilizing formulations of a trivalent inactivated poliovirus vaccine in a dried state for delivery in the Nanopatch™ microprojection array
The worldwide switch to inactivated polio vaccines (IPV) is a key component of the overall strategy to achieve and maintain global polio eradication. To this end, new IPV vaccine delivery systems may enhance patient convenience and compliance. In this work, we examine NanopatchTM (a solid, polymer micro-projection array) which offers potential advantages over standard needle/syringe administration including intradermal delivery and reduced antigen doses. Using trivalent IPV (tIPV) and a purpose-built evaporative dry-down system, candidate tIPV formulations were developed to stabilize tIPV during the drying process and upon storage. Identifying conditions to minimize tIPV potency losses during rehydration and potency testing was a critical first step. Various classes and types of pharmaceutical excipients (~50 total) were then evaluated to mitigate potency losses (measured through D-antigen ELISAs for IPV1, IPV2, and IPV3) during drying and storage. Various concentrations and combinations of stabilizing additives were optimized in terms of tIPV potency retention, and two candidate tIPV formulations containing a cyclodextrin and a reducing agent (e.g., glutathione), maintained ≥80% D-antigen potency during drying and subsequent storage for 4 weeks at 4˚C, and ≥60% potency for 3 weeks at room temperature with the majority of losses occurring within the first day of storage.
References:
* Wan, Y., et al. (in press), Development of Stabilizing Formulations of a Trivalent Inactivated Poliovirus Vaccine in a Dried State for Delivery in the Nanopatch™ Microprojection Array. Journal of Pharmaceutical Sciences. 2018.
Acknowledgements: This work was funded by The World Health Organization
Purification of the food-borne carcinogens 2-amino-3-methylimidazo [4,5-f]quinoline and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline in heated meat products by immunoaffinity chromatography
A rapid and simple scheme has been developed for the isolation and purification of two of the major mutagenic heterocyclic amines formed in heated beef products by affinity chromatography using monoclonal antibodies which recognize 2-amino-3-methylimidazo(4,5-f]quinoline (IQ). Two cell lines producing IgG antibodies were established following fusion of Sp2 or P3x.63 myeloma cells with spleen cells of immunized BALB/cby mice. The antigen was bovine gamma globulin haptenized with 2-(3-carboxypropylthio)-3-methylimidazo[4,5-f]quinoline. The antibodies were immobilized on CNBr-activated Sepharose 4B. IQ and MeIQx formed in heated beef products were partially purified by XAD-2 chromatography and then applied to the affinity columns. Purification by affinity chromatography was adequate for subsequent quantitative analysis by HPLC with UV detection. With this purification scheme as little as 1 g of beef extract or 15 g of fried beef could be assayed for IQ and MeIQx at the part per billion level. Both antibodies had similar affinity constants for IQ (9.3 × 106 and 6.7 × 106 M−1) and for MeIQx (7.1 × 105 and 2.7 × 105 M−1) and both were suitable for immunoaffinity purification of IQ from complex mixtures. MAb2 could be used as well to selectively remove MeIQx from meat products after partial purification by XAD-2. MAb1, despite having a 3-fold higher affinity than MAb2 for MeIQx, could not be used for affinity chromatography for this mutage
The Rest-Frame Optical Luminosity Density, Color, and Stellar Mass Density of the Universe from z=0 to z=3
We present the evolution of the rest-frame optical luminosity density, of the
integrated rest-frame optical color, and of the stellar mass density for a
sample of Ks-band selected galaxies in the HDF-S. We derived the luminosity
density in the rest-frame U, B, and V-bands and found that the luminosity
density increases by a factor of 1.9+-0.4, 2.9+-0.6, and 4.9+-1.0 in the V, B,
and U rest-frame bands respectively between a redshift of 0.1 and 3.2. We
derived the luminosity weighted mean cosmic (U-B)_rest and (B-V)_rest colors as
a function of redshift. The colors bluen almost monotonically with increasing
redshift; at z=0.1, the (U-B)_rest and (B-V)_rest colors are 0.16 and 0.75
respectively, while at z=2.8 they are -0.39 and 0.29 respectively. We derived
the luminosity weighted mean M/LV using the correlation between (U-V)_rest and
log_{10} M/LV which exists for a range in smooth SFHs and moderate extinctions.
We have shown that the mean of individual M/LV estimates can overpredict the
true value by ~70% while our method overpredicts the true values by only ~35%.
We find that the universe at z~3 had ~10 times lower stellar mass density than
it does today in galaxies with LV>1.4 \times 10^{10} h_{70}^-2 Lsol. 50% of the
stellar mass of the universe was formed by $z~1-1.5. The rate of increase in
the stellar mass density with decreasing redshift is similar to but above that
for independent estimates from the HDF-N, but is slightly less than that
predicted by the integral of the SFR(z) curve.Comment: 19 pages, 12 figures, Accepted for Publication in the Dec. 20, 2003
edition of the Astrophysical Journal. Minor changes made to match the
accepted version including short discussions on the effects of clustering and
on possible systematic effects resulting from photometric redshift error
- …