140 research outputs found
Unfolding Drift Effects for Cosmic Rays over the Period of the Sun's Magnetic Field Reversal
A well-established, comprehensive 3-D numerical modulation model is applied
to simulate galactic protons, electrons and positrons from May 2011 to May
2015, including the solar magnetic polarity reversal of Solar Cycle 24. The
objective is to evaluate how these simulations compare with corresponding AMS
observations for 1.0-3.0 GV, and what underlying physics follows from this
comparison in order to improve our understanding on how the major physical
modulation processes change, especially particle drift, from a negative to a
positive magnetic polarity cycle. Apart from their local interstellar spectra,
electrons and positrons differ only in their drift patterns, but they differ
with protons in other ways such as their adiabatic energy changes at lower
rigidity. In order to complete the simulations for oppositely charged
particles, antiproton modeling results are obtained as well. Together, the
observations and the corresponding modeling indicate the difference in the
drift pattern before and after the recent polarity reversal and clarify to a
large extent the phenomenon of charge-sign dependence during this period. The
effect of global particle drift became negligible during this period of no
well-defined magnetic polarity. The resulting low values of all particles' MFPs
during the polarity reversal contrast their large values during solar minimum
activity, and as such expose the relative contributions and effects of the
different modulation processes from solar minimum to maximum activity. We find
that the drift scale starts recovering just after the polarity reversal, but
the MFPs keep decreasing or remain unchanged for some period after the polarity
reversal.Comment: Submitted to Astrophysical Journal, 27 pages, 13 Figure
Geometry Analysis and Simulation in Shoe Centerless Grinding
In this paper, the geometry relationship of shoe centerless grinding for predicting the profile of workpiece is presented. Based on the model, critical parameters are studied. The model was compared with experimental results obtained from grinding trials
Effects of Loading-Dose Statins Combined with PCSK9 Inhibitor Pre-Treatment before Primary Percutaneous Coronary Intervention on the Short-Term Prognosis in Patients with ST-Segment Elevation Myocardial Infarction
Objective: This study was aimed at investigating the effects of preoperative treatment with a loading dose of statins combined with a PCSK9 inhibitor on coronary blood perfusion and short-term cardiovascular adverse events in patients with ST-segment elevation myocardial infarction (STEMI). Method: Sixty-five patients with STEMI who had visited the Shanxi Cardiovascular Disease Hospital between May 2018 and May 2021 were enrolled in the study. The enrolled patients had no history of oral statins or antiplatelet therapy. The patients were divided into a combined treatment group (loading dose of statins combined with PCSK9 inhibitors, 35 patients) and a routine treatment group (loading dose of statins only, 30 patients). The primary endpoints were thrombolysis in myocardial infarction (TIMI) blood flow grading, corrected TIMI frame count (CTFC), and TIMI myocardial perfusion grading (TMPG), immediately after and 30 days after the operation. The secondary endpoint was a composite endpoint of cardiovascular death, nonfatal myocardial infarction, and target vessel revascularization 30 days after the operation. Results: The combined treatment group had significantly lower CTFC (14.09±8.42 vs 26±12.42, P=0.04) and better TMPG (2.74±0.61 vs 2.5±0.73, P=0.04) than the routine treatment group immediately after the operation. Similarly, the combined treatment group had a significantly lower CTFC (16.29±7.39 vs 26.23±11.53, P=0.04) and significantly better TMPG (2.94±0.24 vs 2.76±0.43, P=0.01) than the routine treatment group 1 month after the operation. Conclusion: Preoperative treatment with a loading dose of high-intensity statins combined with PCSK9 inhibitors increased coronary blood flow and myocardial perfusion after emergency thrombus aspiration in patients with STEMI. However, the treatment did not significantly decrease the incidence of cardiovascular death, nonfatal myocardial infarction, or target vessel revascularization
Theory-based Causal Transfer: Integrating Instance-level Induction and Abstract-level Structure Learning
Learning transferable knowledge across similar but different settings is a
fundamental component of generalized intelligence. In this paper, we approach
the transfer learning challenge from a causal theory perspective. Our agent is
endowed with two basic yet general theories for transfer learning: (i) a task
shares a common abstract structure that is invariant across domains, and (ii)
the behavior of specific features of the environment remain constant across
domains. We adopt a Bayesian perspective of causal theory induction and use
these theories to transfer knowledge between environments. Given these general
theories, the goal is to train an agent by interactively exploring the problem
space to (i) discover, form, and transfer useful abstract and structural
knowledge, and (ii) induce useful knowledge from the instance-level attributes
observed in the environment. A hierarchy of Bayesian structures is used to
model abstract-level structural causal knowledge, and an instance-level
associative learning scheme learns which specific objects can be used to induce
state changes through interaction. This model-learning scheme is then
integrated with a model-based planner to achieve a task in the OpenLock
environment, a virtual ``escape room'' with a complex hierarchy that requires
agents to reason about an abstract, generalized causal structure. We compare
performances against a set of predominate model-free reinforcement learning(RL)
algorithms. RL agents showed poor ability transferring learned knowledge across
different trials. Whereas the proposed model revealed similar performance
trends as human learners, and more importantly, demonstrated transfer behavior
across trials and learning situations.Comment: Accepted to AAAI 2020 as an ora
Canagliflozin alters the gut, oral, and ocular surface microbiota of patients with type 2 diabetes mellitus
BackgroundModifications in the gut microbiota may be a crucial factor in the efficacy of canagliflozin (Cana) in managing patients with type 2 diabetes mellitus (T2DM). However, the interplay between oral and ocular surface microbiota and this treatment remains poorly explored.AimThis study aimed to assess alterations in the gut, oral, and ocular surface microbiota pre- and post-Cana treatment in patients with T2DM.MethodsIn this 30-day, controlled before-and-after study, 21 treatment-naïve patients with T2DM received sole treatment with Cana (100 mg/day), and were matched with 10 healthy controls based on gender and age. Using 16S rRNA sequencing, changes in the gut, oral, and ocular surface microbiota pre- and post-Cana treatment were assessed and compared with those of healthy controls. Concurrently, diabetes-related clinical parameters were recorded over the study period. The trial was registered in the Chinese Clinical Trial Registry (ChiCTR200034878).ResultsA noticeable shift was observed in the gut, oral, and ocular surface microbiota pre- and post-Cana treatment. The post-Cana treatment gut microbiota was more similar to that of the healthy controls. Network correlation analysis revealed that modifications in the gut, oral, and ocular surface microbiota were related to changes in clinical parameters, especially for the ocular surface microbiota.Clinical parametersA significant decrease in fasting plasma glucose (8.22 ± 2.19 vs 6.87 ± 1.09 mmol/L), glycated serum protein [291.00 (264.00, 353.00) vs 275.00 (251.00, 342.50) μmol/L], hemoglobin A1c (7.39 ± 1.18 vs 7.12 ± 1.33%), body mass index (25.32 ± 2.99 vs 24.83 ± 2.95 kg/m2), systolic blood pressure (129.05 ± 17.51 vs 123.43 ± 14.82 mmHg), and urinary creatinine [158.40 (74.75, 219.15) vs 79.70 (56.25, 138.10) μmmol/kg] levels was noted after 30-day Cana monotherapy (P < 0.05).Gut microbiomeTreatment with Cana resulted in an increase in the relative abundance of short-chain fatty acid (SCFA)-producing bacteria, particularly Lachnospiraceae UCG 004, Bacteroides, and Lachnospiraceae NK4A136 group.Oral microbiotaAfter Cana treatment, a significant increase of Prevotella and Veillonella, both of which are known to be closely associated with SCFAs, was observed.Ocular surface microbiotaPost-Cana administration, the ocular surface microbiota exhibited the most distinct changes in structure and composition. Remarkably, the majority of the increased ocular surface microbiota could produce SCFAs within the gut microbiota.ConclusionCana effectively improved the dysregulated glucose metabolism in patients with T2DM. This improvement can potentially be attributed to the restoration of balance among the gut, oral, and ocular surface microbial communities.Clinical trial registrationhttps://www.chictr.org.cn/showproj.html?proj=56487, identifier ChiCTR2000034878
Advancing kidney xenotransplantation with anesthesia and surgery - bridging preclinical and clinical frontiers challenges and prospects
Xenotransplantation is emerging as a vital solution to the critical shortage of organs available for transplantation, significantly propelled by advancements in genetic engineering and the development of sophisticated immunosuppressive treatments. Specifically, the transplantation of kidneys from genetically engineered pigs into human patients has made significant progress, offering a potential clinical solution to the shortage of human kidney supply. Recent trials involving the transplantation of these modified porcine kidneys into deceased human bodies have underscored the practicality of this approach, advancing the field towards potential clinical applications. However, numerous challenges remain, especially in the domains of identifying suitable donor-recipient matches and formulating effective immunosuppressive protocols crucial for transplant success. Critical to advancing xenotransplantation into clinical settings are the nuanced considerations of anesthesia and surgical practices required for these complex procedures. The precise genetic modification of porcine kidneys marks a significant leap in addressing the biological and immunological hurdles that have traditionally challenged xenotransplantation. Yet, the success of these transplants hinges on the process of meticulously matching these organs with human recipients, which demands thorough understanding of immunological compatibility, the risk of organ rejection, and the prevention of zoonotic disease transmission. In parallel, the development and optimization of immunosuppressive protocols are imperative to mitigate rejection risks while minimizing side effects, necessitating innovative approaches in both pharmacology and clinical practices. Furthermore, the post-operative care of recipients, encompassing vigilant monitoring for signs of organ rejection, infectious disease surveillance, and psychological support, is crucial for ensuring post-transplant life quality. This comprehensive care highlights the importance of a multidisciplinary approach involving transplant surgeons, anesthesiologists, immunologists, infectiologists and psychiatrists. The integration of anesthesia and surgical expertise is particularly vital, ensuring the best possible outcomes of those patients undergoing these novel transplants, through safe procedural practices. As xenotransplantation moving closer to clinical reality, establishing consensus guidelines on various aspects, including donor-recipient selection, immunosuppression, as well as surgical and anesthetic management of these transplants, is essential. Addressing these challenges through rigorous research and collective collaboration will be the key, not only to navigate the ethical, medical, and logistical complexities of introducing kidney xenotransplantation into mainstream clinical practice, but also itself marks a new era in organ transplantation
Molecular Evolution and Stress and Phytohormone Responsiveness of SUT Genes in Gossypium hirsutum
Sucrose transporters (SUTs) play key roles in allocating the translocation of assimilates from source to sink tissues. Although the characteristics and biological roles of SUTs have been intensively investigated in higher plants, this gene family has not been functionally characterized in cotton. In this study, we performed a comprehensive analysis of SUT genes in the tetraploid cotton Gossypium hirsutum. A total of 18 G. hirsutum SUT genes were identified and classified into three groups based on their evolutionary relationships. Up to eight SUT genes in G. hirsutum were placed in the dicot-specific SUT1 group, while four and six SUT genes were, respectively, clustered into SUT4 and SUT2 groups together with members from both dicot and monocot species. The G. hirsutum SUT genes within the same group displayed similar exon/intron characteristics, and homologous genes in G. hirsutum At and Dt subgenomes, G. arboreum, and G. raimondii exhibited one-to-one relationships. Additionally, the duplicated genes in the diploid and polyploid cotton species have evolved through purifying selection, suggesting the strong conservation of SUT loci in these species. Expression analysis in different tissues indicated that SUT genes might play significant roles in cotton fiber elongation. Moreover, analyses of cis-acting regulatory elements in promoter regions and expression profiling under different abiotic stress and exogenous phytohormone treatments implied that SUT genes, especially GhSUT6A/D, might participate in plant responses to diverse abiotic stresses and phytohormones. Our findings provide valuable information for future studies on the evolution and function of SUT genes in cotton
A Combined Approach of High-Throughput Sequencing and Degradome Analysis Reveals Tissue Specific Expression of MicroRNAs and Their Targets in Cucumber
MicroRNAs (miRNAs) are endogenous small RNAs playing an important regulatory function in plant development and stress responses. Among them, some are evolutionally conserved in plant and others are only expressed in certain species, tissue or developmental stages. Cucumber is among the most important greenhouse species in the world, but only a limited number of miRNAs from cucumber have been identified and the experimental validation of the related miRNA targets is still lacking. In this study, two independent small RNA libraries from cucumber leaves and roots were constructed, respectively, and sequenced with the high-throughput Illumina Solexa system. Based on sequence similarity and hairpin structure prediction, a total of 29 known miRNA families and 2 novel miRNA families containing a total of 64 miRNA were identified. QRT-PCR analysis revealed that some of the cucumber miRNAs were preferentially expressed in certain tissues. With the recently developed ‘high throughput degradome sequencing’ approach, 21 target mRNAs of known miRNAs were identified for the first time in cucumber. These targets were associated with development, reactive oxygen species scavenging, signaling transduction and transcriptional regulation. Our study provides an overview of miRNA expression profile and interaction between miRNA and target, which will help further understanding of the important roles of miRNAs in cucumber plants
Measurement of the WW production cross section in p anti-p collisions at s**(1/2) = 1.96 TeV
We present a measurement of the W boson pair-production cross section in p
anti-p collisions at a center-of-mass energy of sqrt{s}=1.96 TeV. The data,
collected with the Run II DO detector, correspond to an integrated luminosity
of 224-252 pb^-1 depending on the final state (ee, emu or mumu). We observe 25
candidates with a background expectation of
8.1+/-0.6(stat)+/-0.6(syst)+/-0.5(lum) events. The probability for an upward
fluctuation of the background to produce the observed signal is 2.3x10^-7,
equivalent to 5.2 standard deviations.The measurement yields a cross section of
13.8+4.3/-3.8(stat)+1.2/-0.9(syst)+/-0.9(lum) pb, in agreement with predictions
from the standard model.Comment: submitted to PR
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