Cosmic Ray Albedo Neutron Decay (CRAND) has been recently confirmed as a source of energetic electrons at the inner edge of the inner belt by the Colorado Student Space Weather Experiment (CSSWE) ...mission. Here we use observations from the Detection of Electro‐Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) mission, to investigate the CRAND contribution to inner belt electrons quantitatively over a broad energy range (~100–800 keV). Spectral fitting analysis supports the conclusion that CRAND is the most important electron source at the inner edge of the inner belt. For the first time, we show that CRAND is the dominant source of >250‐keV quasitrapped electrons throughout the inner belt and slot region during quiet times. We suggest that additional sources for <250‐keV electrons exist, perhaps from inward transport. In contrast, dynamics of electrons in the inner belt and slot region is dominated by injections during active times.
Plain Language Summary
Albedo neutrons are produced when cosmic ray particles (energetic protons and alpha particles) enter the Earth's atmosphere and then decay into protons, electrons, and antineutrinos, which is known as the Cosmic Ray Albedo Neutron Decay (CRAND) process. The produced energetic protons fill up the inner proton radiation belt, but the CRAND‐produced electrons were not expected to be an important source of the electron belts until measurements from the Colorado Student Space Weather Experiment (CSSWE) mission recently showed that 500‐keV electrons at the inner edge of the inner belt are produced by CRAND. This study uses measurements from the Detection of Electro‐Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) mission and analyze the electron energy spectrum over a broad energy range (~100–800 keV), combining the theoretical calculation of the energy spectrum of CRAND‐produced electrons, to confirm CRAND is the dominant electron source at the inner edge of the inner belt. Furthermore, we show that CRAND is also an important source of >250‐keV quasitrapped electrons (freshly produced ones) in the inner belt and slot region during quiet times. This study discusses the CRAND contribution to the radiation belt electrons and shows that with the knowledge of this new electron source, some other physics processes, such as pitch angle scattering, need to be revisited and quantified.
Key Points
CRAND‐produced electrons are identified unequivocally by both CSSWE and DEMETER at the inner edge of the inner belt
The electron source at low L, where no trapped electrons exist, is validated to be CRAND through a study of energy spectra
During quiet times, CRAND is the dominant source of >250‐keV quasitrapped electrons for the entire inner belt and slot region
In this work, the effect of a time-varying contact surface on friction-induced vibration and noise (FIVN) and surface wear performance was studied experimentally. A certain size groove was fabricated ...on a surface of compacted graphite iron, then filled with pure phenolic resin and phenolic resin with MoS2 additives to obtain a surface with time-varying contact characteristics. The experiment was carried out in a ball-on-flat configuration. The results show that introducing the filler of phenolic resin with MoS2 additives into the groove is effective not only at suppressing the generation of FIVN and improving surface wear performance, but also at alleviating the impact vibration between the groove edge and the ball. More importantly, the time-varying contact surfaces designed in this work are valuable for exploring the role played by debris in the modification of wear state and the formation of interfacial characteristics, and how this finally affects the generation of FIVN. The investigation shows that a time-varying contact surface filled with suitable materials can realize the aim of FIVN reduction.
•Effect of time-varying contact surface on interfacial tribological behaviour is studied.•Wear features at different stages show the inherent relation between FIVN and wear.•The filler affecting wear features and FIVN generation are discussed.•A FIVN reduction mechanism by modifying time-varying contact surface is proposed.
The permeability and porosity of a porous sandstone under cyclic loading–unloading conditions are measured using an integrated permeability and porosity measurement system. Mineral content analysis ...of the rock is performed. The rock contains open microcracks and pores, which can be closed after cyclic loading–unloading; as a result, the permeability and porosity decrease. Based on the test results, the empirical relations of confining stress-dependent sandstone permeability and porosity are derived. A power law is suggested to describe the relationship between the stress-dependent porosity and permeability of the sandstone under both loading and unloading conditions within the stress range used in the experiment. The permeability of the sandstone is more sensitive to stress than to porosity. It is inferred from the test results that the evolution of sandstone porosity and permeability is related to the relative movement of particles and the closure of microcracks.
Hepatitis E virus (HEV) is one of the leading causes of acute viral hepatitis worldwide. Although most of HEV infections are asymptomatic, some patients will develop the symptoms, especially pregnant ...women, the elderly, and patients with preexisting liver diseases, who often experience anorexia, nausea, vomiting, malaise, abdominal pain, and jaundice. HEV infection may become chronic in immunosuppressed individuals. In addition, HEV infection can also cause several extrahepatic manifestations. HEV exists in a wide range of hosts in nature and can be transmitted across species. Hence, animals susceptible to HEV can be used as models. The establishment of animal models is of great significance for studying HEV transmission, clinical symptoms, extrahepatic manifestations, and therapeutic strategies, which will help us understand the pathogenesis, prevention, and treatment of hepatitis E. This review summarized the animal models of HEV, including pigs, monkeys, rabbits, mice, rats, and other animals. For each animal species, we provided a concise summary of the HEV genotypes that they can be infected with, the cross-species transmission pathways, as well as their role in studying extrahepatic manifestations, prevention, and treatment of HEV infection. The advantages and disadvantages of these animal models were also emphasized. This review offers new perspectives to enhance the current understanding of the research landscape surrounding HEV animal models.
Aim To determine the accuracy of MRI versus ultrasound for Morton's neuroma. Materials and methods A search was undertaken for clinical studies published in any language in PubMed up to the date of ...December 2013. Studies assessing the accuracy of the ultrasound or MRI for the diagnosis of Morton's neuroma were included. Data were pooled for meta-analysis. Study selection, data collection, and extraction were performed independently by two authors. Meta-disc 1.4 and Revman 5.2 software were applied for statistical analysis. Results The study included 12 studies; 217 patients underwent MRI and 241 underwent ultrasound examinations. There appeared greater diagnostic accuracy for ultrasound than MRI for the diagnosis of Morton's neuroma (ultrasound sensitivity 90%, specificity 88%, positive likelihood ratio 2.77, negative likelihood ratio 0.16 versus MRI sensitivity 93%, specificity 68%, positive likelihood ratio 1.89, negative likelihood ratio 0.19). Conclusions The available evidence suggests that ultrasound can provide better accuracy for the diagnosis of Morton's neuroma than MRI.
Although it is well established that the ventral telencephalon is the primary source of GABAergic cortical interneurons in rodents, little is known about the specification of specific interneuron ...subtypes. It is also unclear whether the potential to achieve a given fate is established at their place of origin or by signals received during their migration to or during their maturation within the cerebral cortex. Using both
in vivo and
in vitro transplantation techniques, we find that two major interneuron subgroups have largely distinct origins within the MGE. Somatostatin (SST)-expressing interneurons are primarily generated within the dorsal MGE, while parvalbumin (PV)-expressing interneurons primarily originate from the ventral MGE. In addition, we show that significant heterogeneity exists between gene expression patterns in the dorsal and ventral MGE. These results suggest that, like the spinal cord, neuronal fate determination in the ventral telencephalon is largely the result of spatially segregated, molecularly distinct microdomains arranged on the dorsal–ventral axis.
Teleosts are characterized by a remarkable breadth of sexual mechanisms including various forms of hermaphroditism. Sparidae is a fish family exhibiting gonochorism or hermaphroditism even in closely ...related species. The sparid Diplodus puntazzo (sharpsnout seabream), exhibits rudimentary hermaphroditism characterized by intersexual immature gonads but single-sex mature ones. Apart from the intriguing reproductive biology, it is economically important with a continuously growing aquaculture in the Mediterranean Sea, but limited available genetic resources. Our aim was to characterize the expressed transcriptome of gonads and brains through RNA-Sequencing and explore the properties of genes that exhibit sex-biased expression profiles.
Through RNA-Sequencing we obtained an assembled transcriptome of 82,331 loci. The expression analysis uncovered remarkable differences between male and female gonads, while male and female brains were almost identical. Focused search for known targets of sex determination and differentiation in vertebrates built the sex-specific expression profile of sharpsnout seabream. Finally, a thorough genetic marker discovery pipeline led to the retrieval of 85,189 SNPs and 29,076 microsatellites enriching the available genetic markers for this species.
We obtained a nearly complete source of transcriptomic sequence as well as marker information for sharpsnout seabream, laying the ground for understanding the complex process of sex differentiation of this economically valuable species. The genes involved include known candidates from other vertebrate species, suggesting a conservation of the toolkit between gonochorists and hermaphrodites.
Fluoride facilitates the remineralization of dental hard tissues and affects bacterial activities. Therefore, it is extensively used as an anti-caries agent in clinical practice and daily life. ...Although some studies focused on understanding Streptococcus mutans’ response to fluoride, the mechanism regulating intrinsic fluoride tolerance is not yet clear. Since the TetR family of transcription factors is associated with multidrug resistance, our aim was to evaluate whether they are related to fluoride tolerance in S. mutans. A mutant library including each S. mutans TetR gene was constructed and the transcription factor fluoride related transcriptional regulator (FrtR) was identified. The in-frame deletion of the S. mutans frtR gene resulted in decreased cell viability under fluoride in both the planktonic state and single-/dual-species biofilms. This in-frame frtR mutant was used for RNA-sequencing and the fluoride related permease gene (frtP) was found as 1 of the downstream genes directly regulated by FrtR. The recombinant FrtR protein was purified, and conserved DNA binding motifs were determined using electrophoretic mobility shift and DNase I footprinting assays. Finally, a series of mutant and complement strains were constructed to perform the minimum inhibitory concentration (MIC) assays, which indicated that frtP upregulation led to the increase of fluoride sensitivity. Collectively, our results indicate that FrtR is an important transcription factor regulating the frtP expression in S. mutans, thus affecting the intrinsic fluoride tolerance. Therefore, this study provides novel insights into a potential target to increase the S. mutans sensitivity to fluoride for a better prevention of dental caries.
Abstract
Chinese hamster ovary cell constructs expressing either the β 1-, β 2- or β 3-adrenergic receptor (AR) were used to determine whether a novel β-AR modulator, lubabegron fumarate (LUB; ...Experior, Elanco Animal Health) might exert greater potency for a specific β-AR subtype. EC50 values calculated based on cAMP accumulation in dose response curves indicate that LUB is highly selective for the β 3-AR subtype, with an EC50 of 6 × 10–9 M, with no detectible agonistic activity at the β 2-AR. We hypothesized that the accumulation of lipolytic markers would reflect the agonist activity at each of the β-receptor subtypes of the specific ligand; additionally, there would be differences in receptor subtype expression in subcutaneous (s.c.) and intrmuscular (i.m.) adipose tissues. Total RNA was extracted from adipose tissue samples and relative mRNA levels for β 1-, β2-, and β 3-AR were measured using real-time quantitative polymerase chain reaction. Fresh s.c. and i.m. adipose tissue explants were incubated with isoproterenol hydrochloride (ISO; β-AR pan-agonist), dobutamine hydrochloride (DOB; specific β 1-AA), salbutamol sulfate (SAL; specific β 2-AA), ractopamine hydrochloride (RAC), zilpaterol hydrochloride (ZIL), BRL-37344 (specific β 3-agonist), or LUB for 30 min following preincubation with theophylline (inhibitor of phosphodiesterase). Relative mRNA amounts for β 1-, β 2-, and β 3-AR were greater (P < 0.05) in s.c. than in i.m. adipose tissue. The most abundant β-AR mRNA in both adipose tissues was the β 2-AR (P < 0.05), with the β 1- and β 3-AR subtypes being minimally expressed in i.m. adipose tissue. ISO, RH, and ZH stimulated the release of glycerol and nonesterified fatty acid (NEFA) from s.c. adipose tissue, but these β-AR ligands did not alter concentrations of these lipolytic markers in i.m. adipose tissue. LUB did not affect glycerol or NEFA concentrations in s.c. or i.m. adipose tissue, but attenuated (P < 0.05) the accumulation of cAMP mediated by the β 1- and β 2-AR ligands DOB and SAL in s.c. adipose tissue. Collectively, these data indicate that bovine i.m. adipose tissue is less responsive than s.c. adipose tissue to β-adrenergic ligands, especially those that are agonists at the β 1- and β3-receptor subtypes. The minimal mRNA expression of the β 1- and β 3 subtypes in i.m. adipose tissue likely limits the response potential to agonists for these β-AR subtypes.
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