The one-dimensional radiative-convective equilibrium model with an explicit hydrologic cycle introduced in part 1 is used to study the sensitivity of the model's atmosphere to large changes in the ...solar forcing, when various cumulus convection parameterizations are used. When the concentration of the absorbing as in the atmosphere is temperature dependent, equilibrium is impossible for values of the solar forcing larger than a critical value. This result is referred to as a runaway greenhouse. The cumulus convection parameterization schemes currently in use in global climate models (GCMs) employ different assumptions about moistening. This causes the critical solar forcing above which a runaway greenhouse occurs to be very sensitive to the cumulus convection scheme employed. Furthermore, we show that the sensitivity of the equilibrium temperature to changes in the solar forcing depends crucially on the microphysics of cumulus convection. For fixed cloud conditions, the critical forcing for a runaway greenhouse to occur is between approximately 1.22 and 1.49 times the global mean value for the Earth, and for clear sky conditions, it is a few percent lower. The runaway greenhouse in the experiments with the mass flux schemes generally occurs more rapidly than in the experiments with the adjustment schemes. In addition, the inability of the hard convective adjustment scheme to produce an efficient vertical transport of moisture, together with the saturation requirement for convection to occur, leads to the breakdown of the radiative-convective equilibria when other processes are not available to provide the necessary vertical transport of water vapor.
Perchlorate salts (mostly magnesium and sodium perchlorate) have been detected on Mars' arctic soil by the Phoenix lander, furthermore chloride salts have been found on the Meridiani and Gusev sites ...and on widespread deposits on the southern Martian hemisphere. The presence of these salts on the surface is not only relevant because of their ability to lower the freezing point of water, but also because they can absorb water vapor and form a liquid solution (deliquesce). We show experimentally that small amounts of sodium perchlorate (∼ 1 mg), at Mars atmospheric conditions, spontaneously absorb moisture and melt into a liquid solution growing into ∼ 1 mm liquid spheroids at temperatures as low as 225 K. Also mixtures of water ice and sodium perchlorate melt into a liquid at this temperature. Our results indicate that salty environments make liquid water to be locally and sporadically stable on present day Mars.
A simple theory for waterspouts RENNO, Nilton O; BLUESTEIN, Howard B
Journal of the atmospheric sciences,
04/2001, Letnik:
58, Številka:
8
Journal Article
Recenzirano
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It is shown that the simple thermodynamic theory for dust devils, proposed by Renno et al., also applies to waterspouts. The theory is based on the thermodynamics of heat engines and predicts the ...central pressure and the wind speed of these convective vortices. Moreover, it provides a simple physical interpretation of their general characteristics. In particular, the heat engine theory shows that convective vortices are more likely to form in the regions where the occurrence of the warmest and moistest updrafts and the coldest and driest downdrafts are supported by the local environment. These are the regions where both the heat input into the convective heat engine is maximum and the solenoidal generation of vorticity is the greatest. This explains why waterspouts are frequently observed near the boundaries between relatively warm and relatively cold waters. Moreover, since the work done by the convective heat engine is equal to the total heat input multiplied by the thermodynamic efficiency, the theory shows that another necessary condition for the formation of intense vortices is the presence of intense convection.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We employ the heat engine framework to derive a simple method for assessing the strength of irreversible processes in global climate models (GCMs). Using the explicit energy budget of an idealized ...GCM, we show that the thermodynamic efficiencies based on the net heating rate and frictional work rate provides a measure of physical and numerical irreversibilities present in either open (e.g., the Hadley circulation) or closed (e.g., the general circulation) circulations. In addition, we show that the Carnot efficiency is useful for assessing the maximum possible efficiency attained by closed circulations. Comparison of the work-based efficiency with that based on the net heating rate and the Carnot efficiency provides a gauge of how close to reversible and ideal the circulations are. A series of experiments with the idealized GCM demonstrate the usefulness of our method and show the sensitivity of an essentially reversible model to changes in physical and numerical parameters such as rotation period and resolution.
The quest for targeted therapies is critical in the battle against cancer. The RAS/MAP kinase pathway is frequently implicated in neoplasia, with ERK playing a crucial role as the most distal kinase ...in the RAS signaling cascade. Our previous research demonstrated that the interaction between ERK and MYD88, an adaptor protein in innate immunity, is crucial for RAS-dependent transformation and cancer cell survival. In this study, we examine the biological consequences of disrupting the ERK-MYD88 interaction through the ERK D-recruitment site (DRS), while preserving ERK’s kinase activity. Our results indicate that EI-52, a small-molecule benzimidazole targeting ERK-MYD88 interaction induces an HRI-mediated integrated stress response (ISR), resulting in immunogenic apoptosis specific to cancer cells. Additionally, EI-52 exhibits anti-tumor efficacy in patient-derived tumors and induces an anti-tumor T cell response in mice in vivo. These findings suggest that inhibiting the ERK-MYD88 interaction may be a promising therapeutic approach in cancer treatment.The interaction between MyD88 and ERK is necessary for RAS-dependent transformation and cancer cell survival. Here, the authors identify benzimidazole compound EI-52 as a disrupter of this interaction and demonstrate its therapeutic efficacy in tumours via ERK dysregulation and the induction of immunogenic cell death.
Physical properties of terrains encountered by the Curiosity rover during the rst 360 sols of operations have been inferred from analysis of the scour zones produced by Sky Crane Landing System ...engine plumes, wheel touch down dynamics, pits produced by Chemical Camera (ChemCam) laser shots, rover wheel traverses over rocks, the extent of sinkage into soils, and the magnitude and sign of rover-based slippage during drives. Results have been integrated with morphologic, mineralogic, and thermophysical properties derived from orbital data, and Curiosity-based measurements, to understand the nature and origin of physical properties of traversed terrains. The hummocky plains (HP) landing site and traverse locations consist ofmoderately to well-consolidated bedrock of alluvial origin variably covered by slightly cohesive, hard-packedbasaltic sand and dust, with both embedded and surface-strewn rock clasts. Rock clasts have been addedthrough local bedrock weathering and impact ejecta emplacement and form a pavement-like surface in whichonly small clasts (5 to 10 cm wide) have been pressed into the soil during wheel passages. The beddedfractured (BF) unit, site of Curiositys rst drilling activity, exposes several alluvial-lacustrine bedrock unitswith little to no soil cover and varying degrees of lithication. Small wheel sinkage values (1 cm) for both HPand BF surfaces demonstrate that compaction resistance countering driven-wheel thrust has been minimaland that rover slippage while traversing across horizontal surfaces or going uphill, and skid going downhill,have been dominated by terrain tilts and wheel-surface material shear modulus values.
In Bos taurus cattle, antimullerian hormone (AMH) has been demonstrated to have a high degree of correlation with ovarian antral follicle count and the number of healthy follicles and oocytes. To ...document the correlation between the plasma concentration of AMH and follicular number in Bos indicus and Bos taurus heifers, Nelore (Bos indicus, n = 16) and Holstein heifers (Bos taurus, n = 16) had their ovarian follicular waves synchronized. After synchronization, ovarian antral follicular population (AFP) was evaluated three times at 60‐day (d) intervals (T‐120 d, 120 days before plasma AMH determination; T‐60 d, 60 days before; and T0, at the time of plasma AMH determination). The plasma AMH concentration was positively correlated with the number of ovarian follicles on the day of the follicular wave emergence in Bos indicus (Nelore) and Bos taurus (Holstein) heifers at each evaluation time (p < 0.05). The AFP was higher in Bos indicus (Nelore) than in Bos taurus (Holstein) heifers (p < 0.05). Similarly, the AMH concentration was higher in Bos indicus (Nelore) than in Bos taurus (Holstein) heifers (p < 0.0001). When heifers were classified as to present high or low AFP according to the mean of the AFP within each genetic group, high‐AFP heifers presented a greater (p < 0.0001) AMH concentration than low‐AFP heifers, regardless of the genetic group. In conclusion, the AFP is positively correlated with plasma AMH concentration in both Bos indicus (Nelore) and Bos taurus (Holstein) heifers. Furthermore, Bos indicus (Nelore) heifers presented both greater plasma AMH concentrations and AFP than Bos taurus (Holstein) heifers.
We aimed to evaluate the effects of post-ruminal supply of urea (PRU) on nutritional status, and liver metabolism of pregnant beef cows during late gestation. Twenty-four Brahman dams, pregnant from ...a single sire, and weighing 545 kg ± 23 kg were confined into individual pens at 174 ± 23 d of gestation, and randomly assigned into one of two dietary treatments up to 270 d of gestation: Control (CON, n = 12), consisting of a basal diet supplemented with conventional urea, where the cows were fed with diets containing 13.5 g conventional urea per kg dry matter; and PRU (PRU, n = 12), consisting of a basal diet supplemented with a urea coated to extensively prevent ruminal degradation while being intestinally digestible, where the cows were fed with diets containing 14,8 g urea protected from ruminal degradation per kg dry matter. Post-ruminal supply of urea reduced the urine levels of 3-methylhistidine (P = 0.02). There were no differences between treatments for dry matter intake (DMI; P = 0.76), total digestible nutrient (TDN) intake (P = 0.30), and in the body composition variables, such as, subcutaneous fat thickness (SFT; P = 0.72), and rib eye area (REA; P = 0.85). In addition, there were no differences between treatments for serum levels of glucose (P = 0.87), and serum levels of glucogenic (P = 0.28), ketogenic (P = 0.72), glucogenic, and ketogenic (P = 0.45) amino acids, neither for urea in urine (P = 0.51) as well as urea serum (P = 0.30). One the other hand, enriched pathways were differentiated related to carbohydrate digestion, and absorption, glycolysis, pyruvate metabolism, oxidative phosphorylation, pentose phosphate pathway, and biosynthesis of amino acids of the exclusively expressed proteins in PRU cows. Shifting urea supply from the rumen to post-ruminal compartments decreases muscle catabolism in cows during late gestation. Our findings indicate that post-ruminal urea supplementation for beef cows at late gestation may improve the energy metabolism to support maternal demands. In addition, the post-ruminal urea release seems to be able to trigger pathways to counterbalance the oxidative stress associated to the increase liver metabolic rate.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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