4,218 research outputs found
An Alternative Accurate Tracer of Molecular Clouds: The "-Factor"
We explore the utility of CI as an alternative high-fidelity gas mass tracer
for Galactic molecular clouds. We evaluate the X-factor for the 609
m carbon line, the analog of the CO X-factor, which is the ratio of the
H column density to the integrated CO(1-0) line intensity. We use
3D-PDR to post-process hydrodynamic simulations of turbulent, star-forming
clouds. We compare the emission of CI and CO for model clouds irradiated by 1
and 10 times the average background and demonstrate that CI is a comparable or
superior tracer of the molecular gas distribution for column densities up to cm. Our results hold for both reduced and full chemical
networks. For our fiducial Galactic cloud we derive an average of
cmKkms and of cmKkms.Comment: 5 pages, 4 figures, 1 table, accepted to MNRAS Letter
The Relationship Between Body Mass Index, Fitness, Socioeconomics, and Academic Accountability School Rating: A Texas Study
Between 1980 and 2000, obesity rates in the United States have doubled for adults and tripled for children (Centers for Disease Control [CDC], 2015). In addition, Texas, the second largest state, ranks 10th for the highest percentage of obesity among youth age 10-17 (CDC, 2015). Nationally, the United States falls behind other countries in high school and college completion rates (Greenstone, Harris, Li, Looney, & Patashnik, 2012), and since 2001 when the No Child Left Behind Act (NCLB) began, school administrators have reduced physical education, art, music, and recess by 44% to increase the time students spent in reading and math courses preparing for standardize tests (Kohl & Cook, 2013). While standardized testing helps measure student learning, it may be that it also contributes to the growing obesity epidemic among youth in America. This study examined the school-level relationship between body mass index (BMI), fitness, socioeconomics, and academic accountability school rating in Texas for 3 separate school years (2010-2011, 2012-2013, and 2013-2014). A significant relationship between BMI, fitness, and academic achievement was found. However, the relationship was inconsistent. This study adds to existing research and uses the most recent data to date
Consumer Research Needs from the Food and Drug Administration on Front-of-Package Nutritional Labeling
Americans have increasingly busy lifestyles and desire quick and nutritious food choices. To provide consumers with at-a-glance nutrition information, many food manufacturers have introduced front-of-package (FOP) nutritional labeling systems. The purpose of this review is to reach out to the marketing and public policy discipline by identifying research needs on FOP systems not only to aid decision making for federal agencies, but also to help advance research on this important topic. We describe the many FOP systems, the FDA\u27s regulatory background and approach to FOP systems, recent experimental research and gaps in knowledge, and research needs on FOP nutrition labeling
Cooperative Binding of Heat Shock Factor to the Yeast \u3ci\u3eHSP82\u3c/i\u3e Promoter In Vivo and In Vitro
revious work has shown that heat shock factor (HSF) plays a central role in remodeling the chromatin structure of the yeastHSP82 promoter via constitutive interactions with its high-affinity binding site, heat shock element 1 (HSE1). The HSF-HSE1 interaction is also critical for stimulating both basal (noninduced) and induced transcription. By contrast, the function of the adjacent, inducibly occupied HSE2 and -3 is unknown. In this study, we examined the consequences of mutations in HSE1, HSE2, and HSE3 on HSF binding and transactivation. We provide evidence that in vivo, HSF binds to these three sites cooperatively. This cooperativity is seen both before and after heat shock, is required for full inducibility, and can be recapitulated in vitro on both linear and supercoiled templates. Quantitative in vitro footprinting reveals that occupancy of HSE2 and -3 by Saccharomyces cerevisiae HSF (ScHSF) is enhanced ∼100-fold through cooperative interactions with the HSF-HSE1 complex. HSE1 point mutants, whose basal transcription is virtually abolished, are functionally compensated by cooperative interactions with HSE2 and -3 following heat shock, resulting in robust inducibility. Using a competition binding assay, we show that the affinity of recombinant HSF for the full-length HSP82promoter is reduced nearly an order of magnitude by a single-point mutation within HSE1, paralleling the effect of these mutations on noninduced transcript levels. We propose that the remodeled chromatin phenotype previously shown for HSE1 point mutants (and lost in HSE1 deletion mutants) stems from the retention of productive, cooperative interactions between HSF and its target binding sites
Use of faeces as an alternative inoculum to caecal content to study in vitro feed digestibility in domesticated ostriches (Struthio camelus var. domesticus)
In order to find an alternative source of inoculum to caecal content for studying the
in vitro feed digestibility in domesticated ostriches (Struthio camelus var. domesticus), caecal content and
faeces of 4 male birds were used as inocula for an in vitro gas production trial.
2. About 1 g of each of 5 substrates (maize silage, CS; alfalfa hay, AH; barley, BG; soybean meal, SM;
beet pulp, BP) was weighed, in quadruplicate per inoculum, in 120 ml flasks; 75 ml of anaerobic medium
and 4ml of reducing solution were added and flasks were kept at 39C. Caecal content and faeces were
diluted respectively 1 : 2 (CI) and 1 : 4 (FI) with an anaerobic medium and were injected into the
respective flasks (10 ml).
3. Gas production was recorded 22 times up to 120 h of incubation and fermentation characteristics
(for instance, degraded organic matter, OMd; potential gas production, A; maximum fermentation rate,
Rmax; time at which it is reached, Tmax; pH; volatile fatty acid, VFA; ammonia) were studied for each
inoculum and substrate.
4. CI and FI showed significant differences in Tmax (1637 vs 1847 h, respectively), propionic (1647 vs
1207 mmoles/l) and butyric acid (650 vs 798 mmoles/l) and ammonia concentration (1718
vs 1995 mmoles/l). The substrates, according to their chemical composition, showed different
fermentation characteristics. However, the regression equations able to estimate some fermentation
characteristics of the caecum from those of faeces were statistically significant and showed R2-values
ranging from 087 to 099.
5. The differences in fermentation pathways of the two inocula did not appear to influence the rate
and extent of OM digestion. Faecal fermentation predicted rates and extent of OM digestion by caecal
fermentation in ostriches; consequently, the faeces could be considered as an alternative to caecal
content to study feed digestibility in the species, although there is a need to undertake further research.
INTRODUCTION
To obtain a useful feed value, it is necessary to
determine digestibility specifically for ostriches,
where the nutritive value of feeds used for diet
formulation is very often erroneously determined
using poultry. The ostrich caecum provides
a suitable environment for the
fermentation of dietary fibre.
Feed digestibility of ostriches in vivo has
been determine
Statistical analysis of Ni nanowires breaking processes: a numerical simulation study
A statistical analysis of the breaking behavior of Ni nanowires is presented.
Using molecular dynamic simulations, we have determined the time evolution of
both the nanowire atomic structure and its minimum cross section (Sm(t)).
Accumulating thousands of independent breaking events, Sm histograms are built
and used to study the influence of the temperature, the crystalline stretching
direction and the initial nanowire size. The proportion of monomers, dimers and
more complex structures at the latest stages of the breaking process are
calculated, finding important differences among results obtained for different
nanowire orientations and sizes. Three main cases have been observed. (A) [111]
stretching direction and large nanowire sizes: the wire evolves from more
complex structures to monomers and dimers prior its rupture; well ordered
structures is presented during the breaking process. (B) Large nanowires
stretched along the [100] and [110] directions: the system mainly breaks from
complex structures (low probability of finding monomers and dimers), having
disordered regions during their breakage; at room temperature, a huge histogram
peak around Sm=5 appears, showing the presence of long staggered pentagonal Ni
wires with ...-5-1-5-... structure. (C) Initial wire size is small: strong size
effects independently on the temperature and stretching direction. Finally, the
local structure around monomers and dimmers do not depend on the stretching
direction. These configurations differ from those usually chosen in static
studies of conductance.Comment: 18 pages, 13 figure
Recommended from our members
Theoretical investigation of transgastric and intraductal approaches for ultrasound-based thermal therapy of the pancreas.
BackgroundThe goal of this study was to theoretically investigate the feasibility of intraductal and transgastric approaches to ultrasound-based thermal therapy of pancreatic tumors, and to evaluate possible treatment strategies.MethodsThis study considered ultrasound applicators with 1.2 mm outer diameter tubular transducers, which are inserted into the tissue to be treated by an endoscopic approach, either via insertion through the gastric wall (transgastric) or within the pancreatic duct lumen (intraductal). 8 patient-specific, 3D, transient, biothermal and acoustic finite element models were generated to model hyperthermia (n = 2) and ablation (n = 6), using sectored (210°-270°, n = 4) and 360° (n = 4) transducers for treatment of 3.3-17.0 cm3 tumors in the head (n = 5), body (n = 2), and tail (n = 1) of the pancreas. A parametric study was performed to determine appropriate treatment parameters as a function of tissue attenuation, blood perfusion rates, and distance to sensitive anatomy.ResultsParametric studies indicated that pancreatic tumors up to 2.5 or 2.7 cm diameter can be ablated within 10 min with the transgastric and intraductal approaches, respectively. Patient-specific simulations demonstrated that 67.1-83.3% of the volumes of four sample 3.3-11.4 cm3 tumors could be ablated within 3-10 min using transgastric or intraductal approaches. 55.3-60.0% of the volume of a large 17.0 cm3 tumor could be ablated using multiple applicator positions within 20-30 min with either transgastric or intraductal approaches. 89.9-94.7% of the volume of two 4.4-11.4 cm3 tumors could be treated with intraductal hyperthermia. Sectored applicators are effective in directing acoustic output away from and preserving sensitive structures. When acoustic energy is directed towards sensitive structures, applicators should be placed at least 13.9-14.8 mm from major vessels like the aorta, 9.4-12.0 mm from other vessels, depending on the vessel size and flow rate, and 14 mm from the duodenum.ConclusionsThis study demonstrated the feasibility of generating shaped or conformal ablative or hyperthermic temperature distributions within pancreatic tumors using transgastric or intraductal ultrasound
Genetic survey of alveolar and cystic echinococcoses in Romania: first molecular evidence of Echinococcus multilocularis in humans in the country
Cystic echinococcosis (CE) and alveolar echinococcosis (AE) are considered as one of the most
important zoonotic diseases in Romania, where they are subject to mandatory reporting. To obtain
more knowledge about the genetic diversity of Echinococcus causative agents of these diseases, 11
isolates from humans and ungulate intermediate hosts from the two regions of Romania were genotyped
using mitochondrial markers. In clinical samples of fi ve patients from north-eastern Romania
(Iasi, Botosani, Vaslui counties), Echinococcus multilocularis was identifi ed as causal agent by cox1
sequence analysis. To the best of our knowledge this fi nding presents the fi rst molecular evidence
of E. multilocularis in humans from Romania. Only two cases of AE in patients were previously documented
in the country by serological methods. In our four patients the most widespread European
variant E5 of E. multilocularis was recorded, whereas in isolate from Vaslui county three nucleotide
substitutions were detected as compared to the most related E5 haplotype. One of these mutations
(411T/G) matched N1 and N2 haplotypes described previously from North America. In six CE samples
retrieved from western Romania (Caras-Severin and Timis counties), two human isolates were
diagnosed as Echinococcus canadensis G7, one as E. granulosus s.s. G1 and one as E. granulosus
s.s. G3 using atp6 and rrnS sequencing. In ungulates, the cattle isolate was allocated to E. granulosus
s.s. G1 and pig isolate to E. canadensis G7. The two G7 fi ndings in humans reinforced the
recent view that G7 was underestimated as compared to the E. granulosus s.s. regarding human
CE threat that can be further employed for identifying sources of infections and establishing suitable
preventive measures
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