Testing swampland conjectures with machine learning Bizet, Nana Cabo; Damian, Cesar; Loaiza-Brito, Oscar ...
The European physical journal. C, Particles and fields,
08/2020, Letnik:
80, Številka:
8
Journal Article
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Odprti dostop
We consider Type IIB compactifications on an isotropic torus
T
6
threaded by geometric and non geometric fluxes. For this particular setup we apply supervised machine learning techniques, namely an ...artificial neural network coupled to a genetic algorithm, in order to obtain more than sixty thousand flux configurations yielding to a scalar potential with at least one critical point. We observe that both stable AdS vacua with large moduli masses and small vacuum energy as well as unstable dS vacua with small tachyonic mass and large energy are absent, in accordance to the refined de Sitter conjecture. Moreover, by considering a hierarchy among fluxes, we observe that perturbative solutions with small values for the vacuum energy and moduli masses are favored, as well as scenarios in which the lightest modulus mass is much smaller than the corresponding AdS vacuum scale. Finally we apply some results on random matrix theory to conclude that the most probable mass spectrum derived from this string setup is that satisfying the Refined de Sitter and AdS scale conjectures.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
An integrated modeling approach was used to connect socioeconomic factors and nutrient management to river export of nitrogen, phosphorus, silica and carbon based on an updated Global NEWS model. ...Past trends (1970–2000) and four future scenarios were analyzed. Differences among the scenarios for nutrient management in agriculture were a key factor affecting the magnitude and direction of change of future DIN river export. In contrast, connectivity and level of sewage treatment and P detergent use were more important for differences in DIP river export. Global particulate nutrient export was calculated to decrease for all scenarios, in part due to increases in dams for hydropower. Small changes in dissolved silica and dissolved organics were calculated for all scenarios at the global scale. Population changes were an important underlying factor for river export of all nutrients in all scenarios. Substantial regional differences were calculated for all nutrient elements and forms. South Asia alone accounted for over half of the global increase in DIN and DIP river export between 1970 and 2000 and in the subsequent 30 years under the Global Orchestration scenario (globally connected with reactive approach to environmental problems); DIN river export decreased in the Adapting Mosaic (globally connected with proactive approach) scenario by 2030, although DIP continued to increase. Risks for coastal eutrophication will likely continue to increase in many world regions for the foreseeable future due to both increases in magnitude and changes in nutrient ratios in river export.
Quantitative Structure-Activity Relationships (QSAR) are based on the hypothesis that changes in molecular structure reflect proportional changes in the observed response or biological activity. In ...order to successfully conduct QSAR studies certain conditions have to be met that are not frequently reported in the literature. This suggests that some authors are not aware of the principle flaws, occasional shortcomings, and circumstantial downsides of QSAR methods. The present paper focuses on prerequisites to set up correct models and on limitations of model applications. Their implications are systematically described and illustrated as pitfalls that have strong implications in QSAR, and possible solutions are suggested. The paper is focused on small scale 2D- and 3D-QSAR studies for lead optimization. The work is enriched with comprehensive comments and non-mathematical explanations for the computer practitioner in Medicinal Chemistry.
The effective calculation of static nonlinear optical properties requires a considerably high accuracy at a reasonable computational cost, to tackle challenging organic and inorganic systems acting ...as precursors and/or active layers of materials in (nano‐)devices. That trade‐off implies to obtain very accurate electronic energies in the presence of externally applied electric fields to consequently obtain static polarizabilities (αij) and hyper‐polarizabilities (βijk and γijkl). Density functional theory is known to provide an excellent compromise between accuracy and computational cost, which is however largely impeded for these properties without introducing range‐separation techniques. We thus explore here the ability of a modern (double‐hybrid and range‐separated) Range‐Separated eXchange Quadratic Integrand Double‐Hybrid exchange‐correlation functional to compete in accuracy with more costly and/or tuned methods, thanks to its robust and parameter‐free nature.
A new family of push-pull biphenyl-azopyrrole compounds
3b-g
and
4b-d
was efficiently obtained
via
a Suzuki cross-coupling reaction between 2-(4′-iodophenyl-azo)-
N
-methyl pyrrole (
1a
) or ...3-(4′-iodophenyl-azo)-1,2,5-trimethyl pyrrole (
2a
) and 4′-substituted phenyl boronic acids in excellent yields. The influence of the π-biphenyl backbone and pyrrole pattern substitution was correlated with their optical properties. Solvatochromic studies
via
UV-visible spectrophotometry revealed that the inclusion of a 4′-nitro-biphenyl fragment favors a red-shift of the main absorption band in these azo compounds compared with their non-substituted analogues. Likewise, optical band-gaps were estimated by means of electronic absorption spectra and correlated with TD-DFT studies. The pyrrole pattern substitution and the π-conjugated backbone exhibit a clear influence on their thermal isomerization kinetics at room temperature. In all cases, biphenylazo-pyrrole compounds lead to the formation of J-type aggregates in binary MeOH : H
2
O solvents. Under these conditions, compounds
3b-c
undergo a water-assisted
cis
-to-
trans
isomerization at room temperature.
New push-pull biphenyl-azopyrrole photoswitches are efficiently obtained
via
a Suzuki cross-coupling reaction, give rise to J-type aggregates in binary MeOH : H
2
O solvents and undergo a water-assisted
cis
-to-
trans
isomerization at room temperature.
To assess the safety of galantamine in subjects with mild cognitive impairment (MCI), the ability of galantamine to benefit cognition and global functioning in subjects with MCI, and the ability of ...galantamine to delay conversion to dementia.
In two studies, 2,048 subjects, 990 in Study 1 and 1,058 in Study 2, with a Clinical Dementia Rating (CDR) = 0.5, CDR memory score > or =0.5, without dementia were randomized to double-blind galantamine (16-24 mg/day) or placebo for 24 months. Primary efficacy endpoint at month 24 was number (%) of subjects who converted from MCI to dementia (CDR > or = 1.0).
There were no differences between galantamine and placebo in 24-month conversion rates (Study 1: 22.9% galantamine vs 22.6% placebo, p = 0.146; Study 2: 25.4% galantamine vs 31.2% placebo, p = 0.619). Mean CDR-sum of boxes declined less with galantamine than placebo at 12 and 24 months in Study 1 (p = 0.024 12 months and p = 0.028 24 months), but not in Study 2 (p = 0.662 12 months and p = 0.056 24 months). Digit Symbol Substitution Test scores improved with galantamine in Study 1 at 12 months and in Study 2 at 24 months (Study 1: p = 0.009 month 12 and p = 0.079 Month 24; Study 2: p = 0.154 month 12 and p = 0.020 month 24). The most frequently reported adverse event was nausea (galantamine, 29%; placebo, 10%). Serious AEs occurred in 19% of each group. Mortality of the cohort after retrospectively determining the status of subjects (98.3%) at 24 months was 1.4% (galantamine) and 0.3% (placebo); RR (95% CI), 1.70 (1.00, 2.90).
Galantamine failed to significantly influence conversion to dementia. Galantamine was generally well tolerated. Whereas recorded mortality was greater in the galantamine group than in the placebo group in the original per-protocol assessment, a post hoc analysis of the cohort was consistent with no increased risk.
Recent advances in neurobehavioral genetics have increased the importance of research on the behavioral patterns of different mouse strains. A comprehensive comparison of inbred and outbred mouse ...strains was conducted to provide information on the range of performance and pharmacological effects in the forced swimming test, a behavioral test commonly used to measure the effects of antidepressant drugs.
Baseline performance and pharmacological responses to desipramine, a selective norepinephrine reuptake inhibitor, and fluoxetine, a selective serotonin reuptake inhibitor, were compared in seven inbred and four outbred mouse strains in the forced swimming test.
Swim sessions were conducted by placing mice in individual glass cylinders filled with water for 6 min. The duration of behavioral immobility during the last 4 min of the test was scored from videotapes.
A 10-fold range of immobility values and coefficient of variation supported the existence of substantial behavioral differences between mouse strains in baseline performance in the FST. In general, inbred strains demonstrated lower variability than outbred strains. Desipramine dose-dependently reduced immobility in seven of the 11 strains tested, with DBA/2J and the C57BL/6J mice showing greater sensitivity than the other strains. In contrast, fluoxetine reduced immobility in only three out of the 11 strains tested, DBA/2J, BALB/cJ and NIH Swiss mice.
Background strain is a critical variable in determining baseline performance and the sensitivity to different types of antidepressant drugs in the mouse FST. The use of such mouse strains may provide information on the genetic basis for strain differences in depressive behavior and differential sensitivity to diverse classes of antidepressants.
The objective of this study was to evaluate the effects of supplementing a Saccharomyces cerevisiae fermentation product (SCFP) on body temperature indices, metabolism, acute phase protein response, ...and production variables during heat stress (HS). Twenty multiparous lactating Holstein cows (body weight = 675 ± 12 kg; days in milk = 144 ± 5; and parity = 2.3 ± 0.1) were used in an experiment conducted in 2 replicates (10 cows/replicate). Cows were randomly assigned to 1 of 2 dietary treatments: control diet (CON; n = 10) or the CON diet supplemented with 19 g/d of SCFP (n = 10; NutriTek, Diamond V, Cedar Rapids, IA). Cows were fed their respective diets for 21 d before initiation of the study. The experiment consisted of 2 periods: thermoneutral (period 1; P1) and heat stress (period 2; P2). During P1 (4 d), cows were fed ad libitum and housed in thermoneutral conditions for collecting baseline data. During P2 (7 d), HS was artificially induced using an electric heat blanket (EHB; Thermotex Therapy Systems Ltd., Calgary, AB, Canada). Cows were fitted with the EHB for the entirety of P2. Rectal temperature, respiration rate, and skin temperature were obtained twice daily (0600 and 1800 h) during both periods. Overall, HS increased rectal temperature, skin temperature, and respiration rate (1.4°C, 4.8°C, and 54 breaths/min, respectively) relative to P1, but no dietary treatment differences were detected. Compared with P1, HS decreased dry matter intake and milk yield (36 and 26%, respectively), and the reductions were similar between dietary treatments. Relative to P1, HS increased milk fat content and milk urea nitrogen (17 and 30%, respectively) and decreased milk protein and lactose contents (7 and 1.4%, respectively). Overall, HS increased (52%) plasma cortisol concentrations of CON, but circulating cortisol did not change in SCFP-fed cows. Heat stress increased circulating lipopolysaccharide binding protein and serum amyloid A (SAA; 2- and 4-fold, respectively), and SCFP supplementation tended to decrease peak SAA (∼33%) relative to CON cows. Overall, although HS did not influence circulating white blood cells and neutrophils, SCFP increased circulating white blood cells and neutrophils by 9 and 26%, respectively, over CON in P2. In conclusion, HS initiated an acute phase protein response and feeding SCFP blunted the cortisol and SAA concentrations and altered some key leukocyte dynamics during HS.
Summary
Non‐steroidal anti‐inflammatory drugs (NSAIDs) are the medications most frequently involved in hypersensitivity drug reactions. Because NSAIDs are prescribed for many conditions, this is a ...world‐wide problem affecting patients of all ages. Various hypersensitivity reactions have been reported, mainly affecting the skin and/or the respiratory airways. The most frequent of these is acute urticaria, which can be induced by several different NSAIDs. Both specific and non‐specific immunological pathways have been proposed as underlying mechanisms. This review presents the clinical phenotypes and the drugs involved in NSAID hypersensitivity. Five major clinical syndromes can be distinguished: aspirin‐exacerbated respiratory disease (AERD), aspirin‐exacerbated cutaneous disease (AECD), multiple NSAID‐induced urticaria/angioedema (MNSAID‐UA), single NSAID‐IgE reactions and single NSAID T cell responses. However, further classification is possible within these five major entities, by detailed descriptions of the clinical characteristics enabling more phenotypes to be defined. This detailed differentiation now seems required in order to undertake appropriate pharmacogenetic studies.
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