PHYS. REV. D 107, 092001 (2023) A new mechanism has been proposed to simultaneously explain the presence of
dark matter and the matter-antimatter asymmetry in the universe. This scenario
predicts ...exotic $B$ meson decays into a baryon and a dark sector anti-baryon
($\psi_D$) with branching fractions accessible at $B$ factories. We present a
search for $B \rightarrow \Lambda \psi_D$ decays using data collected by the
$BABAR$ experiment at SLAC. This reaction is identified by fully reconstructing
the accompanying $B$ meson and requiring the presence of a single $\Lambda$
baryon in the remaining particles. No significant signal is observed, and
bounds on the $B \rightarrow \Lambda \psi_D$ branching fraction are derived in
the range $0.13 - 5.2\times 10^{-5}$ for $1.0 < m_{\psi_D} < 4.2$ GeV/$c^{2}$.
These results set strong constraints on the parameter space allowed by the
theory.
Guttman and Plantico reported on an additive model to describe daily temperature climates. This note reports on spectral analyses of the nonrandom residuals from the model. We concluded that ...quasi-periodic features are not present in the 1951–80 residual maximum and minimum temperature data. Two areas of search for model components are suggested for future research. First, apparent singularities should be investigated and mathematically described. Second, nonstationary patterns over the period of record that may be linked to long term climatic variability should be understood and modeled.
Poliovirus RNA stimulates incorporation of35S from both 35Smethionine and formyl-35Smethionyl-tRNAf
Metin cell-free systems derived from HeLa cells or from poliovirus-infected HeLa cells. The largest ...product formed under the direction of the viral RNA is the same size as the polyprotein thought to represent translation of the entire RNA. Synthesis of this polyprotein and other large products was stimulated greatly by increasing the salt concentration during the reaction from the optimum for initiation (90 mM) to the optimum for elongation (155 mM). Only one initiation peptide could be identified, and a tryptic digest of the product contained mainly peptides that cochromatographed with peptides from authentic viral proteins. The RNA from a deletion mutant of poliovirus initiated protein synthesis at the same site used by standard RNA and programmed synthesis of an appropriately deleted set of polypeptides. The results strongly support the model of translation of poliovirus RNA from a single initiation site into a continuous polyprotein that is cleaved to form the functional proteins. It is suggested that uninfected HeLa cell extracts can carry out the cleavages of nascent polyprotein.
Daily maximum and minimum temperature changes in January over 112 recorded years at Central Park, New York, were analyzed from a statistical viewpoint. The case study reveals that time series of mean ...and median changes are not smooth, that the data are highly variable, that a longer period of record is needed to develop stable statistical distributional relationships, and that there is a tendency, but not conclusive evidence, for a cooling event around 8 January and a "January thaw" around 25 January.
The National Climatic Data Center is committed to archiving and disseminating data of high quality. Automated screening of data has proven to be very effective in isolating suspect and erroneous ...values in large meteorological data sets. However, manual review by validators is required to judge the validity and correct the data that is rejected by the screens. Since the judgment of the validators affects the quality of the data, the efficacy of their actions is of paramount importance. Techniques have been developed to measure whether data validators make the proper decision when editing data. Measurement is accomplished by replacing valid data with known errors (so-called "seeds") and then monitoring the validator's decisions. Procedural details and examples are given. The measurement program has several benefits: (1) validator performance is quantitatively evaluated; (2) limited inferences about data quality can be made; (3) feedback to the validators identifies training requirements and operational procedures that could be improved; and (4) errors of omission as well as of commission are found. It is important to recognize that seeding does not detect errors inserted into the data by validators. Thus, seeding is but one aspect of a comprehensive surveillance mechanism.
Simple washing of live Euglena gracilis cleans the pellicle of external coating material. When these cleaned cells are viewed with a scanning electron microscope, organelle outlines can be seen ...through the thinned pellicle. To view organelles directly, fixed Euglena cells are gently borken first or first frozen and then broken as part of their preparation for scanning electron microscopy. Subsequent viewing at magnifications of × 5,000 to × 21,000 reveals organelles, storage granules, endoplasmic reticulum, and nuclear pores, while retaining great depth of focus.
Estimation of Daily Degree-hours Guttman, Nathaniel B.; Lehman, Richard L.
Journal of applied meteorology,
07/1992, Volume:
31, Issue:
7
Journal Article
Open access
Degree-hours have many applications in fields such as agriculture, architecture, and power generation. Since daily mean temperatures are more readily available than hourly temperatures, the ...difference between mean daily degree-hours computed from daily mean temperatures and those computed from hourly data is examined. Mean daily degree-hours were modeled assuming normal probability distributions for temperatures and homogeneous variances of hourly temperatures throughout a day. The validity of the assumptions, which is dependent upon time of year and location, as well as the effect of the assumptions on four models of daily degree-hours are discussed. Two of the models require mean hourly temperatures and two require the readily available daily mean temperatures as input. Comparisons among models and observed data show that estimates made from mean hourly temperatures are better than those made from daily mean temperatures. The difference is sizable during the transition months between warm and cool seasons. An aid to computing the difference is presented.
Objective: The authors analyzed data from the 1991 National Planning Survey to (a) assess respondents' awareness of three official sources of information about HIV/AIDS (CDC, the Surgeon General, and ...state health departments); (b) assess respondents' perceptions of the reliability of these sources; and (c) compare respondents' personal beliefs about HIV transmission with their beliefs regarding the experts' view. Methods: The authors conducted a secondary analysis of the responses of the 1622 survey participants who gave complete information. Results: People with more years of formal education were more likely to have heard of the CDC and the Surgeon General. The CDC was given the highest overall reliability rating, followed by the Surgeon General and then state health departments. Transmission of HIV/AIDS by various modes of casual contact was perceived more likely among those who gave the CDC lower reliability ratings. However, regardless of their perceptions of the reliability of the CDC as a source of HIV/AIDS information, many respondents believed the probability of transmission by casual contact more likely than they believed experts said it was. Conclusions: The discrepancy found between what people believe about health risks and what they think experts believe has important implications for the design of effective health information campaigns and for the design of questionnaire items that aim to assess people's "knowledge" and "attitudes" regarding sensitive health topics.
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