3,594 research outputs found
Open data and smallholder food and nutritional security
This report was commissioned CTA as a member of the GODAN initiative. It aims to provide a better understanding of the actual impact of the open data movement on the food and nutrition security of smallholders and highlight the areas of potential unfilled opportunity
Kinetics of Surfactant Adsorption at Fluid/Fluid Interfaces: Non-ionic Surfactants
We present a model treating the kinetics of adsorption of soluble
surface-active molecules at the interface between an aqueous solution and
another fluid phase. The model accounts for both the diffusive transport inside
the solution and the kinetics taking place at the interface using a free-energy
formulation. In addition, it offers a general method of calculating dynamic
surface tensions. Non-ionic surfactants are shown, in general, to undergo a
diffusion-limited adsorption, in accord with experimental findings.Comment: 6 pages, 3 figures, see also cond-mat/960814
Moxalactam Therapy for Obstetric and Gynecologic Infections
Moxalactam, a new cephalosporin antibiotic with a broad spectrum of activity, was evaluated for safety and therapeutic efficacy in the treatment of genital tract infections in women. Fifty-three patients with postpartum endometritis or acute or chronic pelvic inflammatory disease were treated with 2 g of moxalactam iv every 8 hr, usually for five days or longer. Appropriate cultures of peripheral blood, endometrium, cul-de-sac aspirates, urine, wound, and endocervix (only for Neisseria gonorrhoeae) were performed. Overall, 90.6% (48 of 53) of the patients were successfully treated with moxalactam - 86.2% (25 of 29) and 95.8% (23 of 24) of the patients with endometritis and pelvic inflammatory disease, respectively. Therapy failed in one of five bacteremic patients with endometritis. Of all the bacteria isolated from appropriate culture sites, 58% (224 of 383) were anaerobes, with anaerobic gram-negative rods - particularly Bacteroides bivius-and gram-positive cocci being predominant. Of 206 anaerobic strains tested with moxalactam by agar dilution techniques, 82% (169 of 206) were susceptible (minimal inhibitory concentration [MIC], ⩽8 μg/ml), 11.6% (24 of 206) were moderately susceptible (MIC, 16-32 μg/ml), and 6.3% (13 of 206) were resistant (MIC, ⩾64 μg/ml). Among the aerobic isolates, enterococci were uniformly resistant. Thus, moxalactam performed well as a single agent in this open clinical trail for women with infections of the genital trac
Wire + Arc Additive Manufacturing
Depositing large components (>10 kg) in titanium, aluminium, steel and other metals is possible using Wire + Arc Additive Manufacturing. This technology adopts arc welding tools and wire as feedstock for additive manufacturing purposes. High deposition rates, low material and equipment costs, and good structural integrity make Wire+Arc Additive Manufacturing a suitable candidate for replacing the current method of manufacturing from solid billets or large forgings, especially with regards to low and medium complexity parts. A variety of components have been successfully manufactured with this process, including Ti–6Al–4V spars and landing gear assemblies, aluminium wing ribs, steel wind tunnel models and cones. Strategies on how to manage residual stress, improve mechanical properties and eliminate defects such as porosity are suggested. Finally, the benefits of non-destructive testing, online monitoring and in situ machining are discussed
The Hurst Exponent of Fermi GRBs
Using a wavelet decomposition technique, we have extracted the Hurst exponent
for a sample of 46 long and 22 short Gamma-ray bursts (GRBs) detected by the
Gamma-ray Burst Monitor (GBM) aboard the Fermi satellite. This exponent is a
scaling parameter that provides a measure of long-range behavior in a time
series. The mean Hurst exponent for the short GRBs is significantly smaller
than that for the long GRBs. The separation may serve as an unbiased criterion
for distinguishing short and long GRBs.Comment: Accepted for publication in Monthly Notices of the Royal Astronomical
Societ
HATS-13b and HATS-14b: two transiting hot Jupiters from the HATSouth survey
We report the discovery of HATS-13b and HATS-14b, two hot-Jupiter transiting
planets discovered by the HATSouth survey. The host stars are quite similar to
each other (HATS-13: V = 13.9 mag, M* = 0.96 Msun, R* = 0.89 Rsun, Teff = 5500
K, [Fe/H] = 0.05; HATS-14: V = 13.8 mag, M* = 0.97 Msun, R* = 0.93 Rsun, Teff =
5350 K, [Fe/H] = 0.33) and both the planets orbit around them with a period of
roughly 3 days and a separation of roughly 0.04 au. However, even though they
are irradiated in a similar way, the physical characteristics of the two
planets are very different. HATS-13b, with a mass of Mp = 0.543 MJ and a radius
of Rp = 1.212 RJ, appears as an inflated planet, while HATS-14b, having a mass
of Mp = 1.071 MJ and a radius of Rp = 1.039 RJ, is only slightly larger in
radius than Jupiter.Comment: 13 pages, 7 figures, Submitted to Astronomy & Astrophysics. arXiv
admin note: text overlap with arXiv:1503.0006
Age Differences in the Association of Obstructive Sleep Apnea Risk with Cognition and Quality of Life
Using a sample of 2925 stroke-free participants drawn from a national population-based study, we examined cross-sectional associations of obstructive sleep apnea risk (OSA) with cognition and quality of life and whether these vary with age, while controlling for demographics and co-morbidities. Included participants from the REasons for Geographic And Racial Differences in Stroke Study were aged 47-93. OSA risk was categorized as high or low based on responses to the Berlin Sleep Questionnaire. Cognitive function was assessed with standardized fluency and recall measures. Depressive symptoms were assessed with the four-item Center for Epidemiologic Studies Depression Scale. Health-related Quality of Life (HRQoL) was assessed with the Medical Outcomes Study Short Form-12 (SF-12). MANCOVA statistics were applied separately to the cognitive and quality of life dependent variables while accounting for potential confounders (demographics, co-morbidities). In fully adjusted models, those at high risk for OSA had significantly lower cognitive scores (Wilks’ Lambda = 0.996, F(3, 2786) = 3.31, p < .05) and lower quality of life (depressive symptoms and HRQoL) (Wilks’ Lambda = 0.989, F(3, 2786) = 10.02, p < .0001). However, some of the associations were age-dependent. Differences in cognition and quality of life between those at high and low obstructive sleep apnea risk were most pronounced during middle age, with attenuated effects after age 70
Ongoing monitoring of Tortugas Ecological Reserve: Assessing the consequences of reserve designation
Over the past five years, a biogeographic characterization of Tortugas Ecological Reserve(TER) has been carried out to measure the post-implementation effects of TER as a refuge for exploited species. Our results demonstrate that there is substantial microalgal biomass at depths between 10 and 30 m in the soft sediments at the coral reef interface, and that this community may play an important role in the food web supporting reef organisms. In addition, preliminary
stable isotope data, in conjunction with prior results from the west Florida shelf, suggest that the shallow water benthic habitats surrounding the coral reefs of TER will prove to be an important source of the primary production ultimately fueling fish production throughout TER. The
majority of the fish analyzed so far have exhibited a C isotope signature consistent with a food web which relies heavily on benthic primary production. Fish counts indicate a marked increase in the abundance of large fish (>20 cm) within the Reserve relative to the Out and Park strata,
across years. Faunal collections from open and protected soft bottom habitat near the northern boundary of Tortugas North strongly suggest that relaxation of trawling pressure has increased benthic biomass and diversity in this area of TER. These data, employing an integrated Before -
After Control Impact (BACI) design at multiple spatial scales, will allow us to continue to document and quantify the post-implementation effects of TER. (PDF contains 58 pages
BLUF Domain Function Does Not Require a Metastable Radical Intermediate State
BLUF
(blue light using flavin) domain proteins are an important
family of blue light-sensing proteins which control a wide variety
of functions in cells. The primary light-activated step in the BLUF
domain is not yet established. A number of experimental and theoretical
studies points to a role for photoinduced electron transfer (PET)
between a highly conserved tyrosine and the flavin chromophore to
form a radical intermediate state. Here we investigate the role of
PET in three different BLUF proteins, using ultrafast broadband transient
infrared spectroscopy. We characterize and identify infrared active
marker modes for excited and ground state species and use them to
record photochemical dynamics in the proteins. We also generate mutants
which unambiguously show PET and, through isotope labeling of the
protein and the chromophore, are able to assign modes characteristic
of both flavin and protein radical states. We find that these radical
intermediates are not observed in two of the three BLUF domains studied,
casting doubt on the importance of the formation of a population of
radical intermediates in the BLUF photocycle. Further, unnatural amino
acid mutagenesis is used to replace the conserved tyrosine with fluorotyrosines,
thus modifying the driving force for the proposed electron transfer
reaction; the rate changes observed are also not consistent with a
PET mechanism. Thus, while intermediates of PET reactions can be observed
in BLUF proteins they are not correlated with photoactivity, suggesting
that radical intermediates are not central to their operation. Alternative
nonradical pathways including a keto–enol tautomerization induced
by electronic excitation of the flavin ring are considered
On the Pulse Intensity Modulation of PSR B0823+26
We investigate the radio emission behaviour of PSR B0823+26, a pulsar which
is known to undergo pulse nulling, using an 153-d intensive sequence of
observations. The pulsar is found to exhibit both short (~min) and unusually
long-term (~hours or more) nulls, which not only suggest that the source
possesses a distribution of nulling timescales, but that it may also provide a
link between conventional nulling pulsars and longer-term intermittent pulsars.
Despite seeing evidence for periodicities in the pulsar radio emission, we are
uncertain whether they are intrinsic to the source, due to the influence of
observation sampling on the periodicity analysis performed. Remarkably, we find
evidence to suggest that the pulsar may undergo pre-ignition periods of
'emission flickering', that is rapid changes between radio-on (active) and -off
(null) emission states, before transitioning to a steady radio-emitting phase.
We find no direct evidence to indicate that the object exhibits any change in
spin-down rate between its radio-on and -off emission modes. We do, however,
place an upper limit on this variation to be <= 6 % from simulations. This
indicates that emission cessation in pulsars does not necessarily lead to large
changes in spin-down rate. Moreover, we show that such changes in spin-down
rate will not be discernible in the majority of objects which exhibit
short-term (<= 1 d) emission cessation. In light of this, we predict that many
pulsars could exhibit similar magnetospheric and emission properties to PSR
B0823+26, but which have not yet been observed.Comment: 13 pages, 11 figures, accepted for publication in MNRAS; 1 reference
correcte
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