Machine learning techniques are now well established in experimental particle physics, allowing detector data to be analyzed in new and unique ways. The identification of signals in particle ...observatories is an essential data processing task that can potentially be improved using such methods. This paper aims at exploring the benefits that a dedicated machine learning approach might provide to the classification of signals in dual-phase noble gas time projection chambers. A full methodology is presented, from exploratory data analysis using Gaussian mixture models and feature importance ranking to the construction of dedicated predictive models based on standard implementations of neural networks and random forests, validated using unlabeled simulated data from the LZ experiment as a proxy to real data. The global classification accuracy of the predictive models developed in this work is estimated to be >99.0%, which is an improvement over conventional algorithms tested with similar data. The results from the clustering analysis were also used to identify anomalies in the data caused by miscalculated signal properties, showing that this methodology can also be used for data monitoring.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In females, most genes on the X chromosome are generally assumed to be transcriptionally silenced on the inactive X as a result of X inactivation. However, particularly in humans, an increasing ...number of genes are known to "escape" X inactivation and are expressed from both the active (Xa) and inactive (Xi) X chromosomes; such genes reflect different molecular and epigenetic responses to X inactivation and are candidates for phenotypes associated with X aneuploidy. To identify genes that escape X inactivation and to generate a first-generation X-inactivation profile of the X, we have evaluated the expression of 224 X-linked genes and expressed sequence tags by reverse-transcription-PCR analysis of a panel of multiple independent mouse/human somatic cell hybrids containing a normal human Xi but no Xa. The resulting survey yields an initial X-inactivation profile that is estimated to represent ≈ 10% of all X-linked transcripts. Of the 224 transcripts tested here, 34 (three of which are pseudoautosomal) were expressed in as many as nine Xi hybrids and thus appear to escape inactivation. The genes that escape inactivation are distributed nonrandomly along the X; 31 of 34 such transcripts map to Xp, implying that the two arms of the X are epigenetically and/or evolutionarily distinct and suggesting that genetic imbalance of Xp may be more severe clinically than imbalance of Xq. A complete X-inactivation profile will provide information relevant to clinical genetics and genetic counseling and should yield insight into the genomic and epigenetic organization of the X chromosome.
Effects of Sled Towing on Sprint Starts Cottle, Casey A; Carlson, Lara A; Lawrence, Michael A
Journal of strength and conditioning research
28, Številka:
5
Journal Article
Recenzirano
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ABSTRACTCottle, CA, Carlson, LA, and Lawrence, MA. Effects of sled towing on sprint starts. J Strength Cond Res 28(5)1241–1245, 2014—Sled towing is a popular method of sprint training. Researchers ...have struggled to identify a loading scheme that is most appropriate to improve sprint performance in the acceleration phase. The purpose of this study was to determine if loads of 10% body weight (BWT) or 20% BWT produced significantly greater propulsive ground reaction force (GRF) impulse, peak propulsive GRF, or a greater propulsive rate of force development (RFD) than an unweighted sprint start. Seventeen healthy court and field athletes (10 men, 7 women; 20.9 ± 1.1 years) completed 5 starts of each condition (unweighted, 10% BWT, 20% BWT). Participants began each start in an upright staggered stance. Propulsive GRF impulse was greater in the 20% BWT condition than the unweighted condition in both limbs and greater in the 20% BWT condition than the 10% BWT condition in the front leg only, and vertical GRF impulse was greater in the 20% BWT than the unweighted condition. In summary, our results suggest that a 10% BWT load is not sufficient to increase propulsive GRF impulse. A loading scheme of 20% BWT is sufficient to increase propulsive GRF impulse. Coaches seeking to improve sprint starts may observe improvements using a load of 20% BWT during training while towing a sled.
Groundwater can influence the geomagnetic field measured underground in at least two key ways. The water levels in rock will determine its electrical conductivity, and thus change the magnitude of ...the telluric currents induced in the rock by changing magnetic fields generated in the ionosphere. This can be studied by using multiple magnetometers at different underground locations. Secondly the flow of water through rock will generate a small magnetic signal, of unknown magnitude, through the electrokinetic effect. SQUID magnetometry has the potential to allow passive studies of groundwater changes in complex systems such as karst. We have monitored geomagnetic signals using two SQUID magnetometers at the LSBB underground laboratory, and set an initial limit on the magnitude of the electrokinetic signal. We now plan to carry out a longer term measurement using three SQUID systems as well as fluxgate sensors to track changes in the gradient of the magnetic field across the underground complex.
Dark matter searches using dual-phase xenon time-projection chambers (LXe-TPCs) rely on their ability to reject background electron recoils (ERs) while searching for signal-like nuclear recoils ...(NRs). ER response is typically calibrated using β -decay sources, such as tritium, but these calibrations do not characterize events accompanied by an atomic vacancy, as in solar neutrino scatters off inner-shell electrons. Such events lead to emission of x rays and Auger electrons, resulting in higher electron-ion recombination and thus a more NR-like response than inferred from β -decay calibration. We present a cross-calibration of tritium β -decays and Xe127 electron-capture decays (which produce inner-shell vacancies) in a small-scale LXe-TPC and give the most precise measurements to date of light and charge yields for the Xe127 L -shell electron-capture in liquid xenon. We observe a 6.9σ ( 9.2σ ) discrepancy in the L -shell capture response relative to tritium β decays, measured at a drift field of 363±14 V /cm ( 258±13 V /cm ), when compared to simulations tuned to reproduce the correct β -decay response. In dark matter searches, use of a background model that neglects this effect leads to overcoverage (higher limits) for background-only multi-kiloton-year exposures, but at a level much less than the 1-σ experiment-to-experiment variation of the 90% C.L. upper limit on the interaction rate of a 50 GeV/c2 dark matter particle.
Rapid land ownership changes in the Northern Forest of the eastern United States have spurred development as well as conservation. Local people have experienced differing degrees of participation in ...land use decisions. We examine two conservation projects from the Northern Forest state of Maine. This paper presents the policy processes from these projects and an assessment of their impact on conflict and support for the project. One project was a top-down approach, and the second was a grassroots, private effort by local citizens to conserve forestland. We gathered data via person interviews, mail surveys, and analysis of legislative testimony.
Our findings indicate that early local involvement leads to less conflict and greater acceptance of the project. Important aspects of effective public involvement include shared learning and two-way dialogue. In addition, we found that regardless of the process employed, respondents were generally satisfied with the outcomes of the processes.
► Analysis of two high profile conservation projects in Maine. ► Mutual learning and two-way dialogue lead to more supported outcomes and processes. ► Identifying goals with local people at the earliest stages is a first step in creating support for a project.
1Current address: SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USAPrecision magnetometry is an essential component of any neutron electric dipole moment experiment ...in order to correct shifts in the neutron precession frequency due to changes in the magnetic field. We have developed a magnetometry system using 12 SQUID sensors, designed to operate in 0.5K superfluid helium. The pick-up loops located near the neutron cell are connected to the SQUID sensors by ~2m twisted wire pairs. The SQUID readout cables are run via an intermediate stage at 4.2K. The system has been installed and tested in the cryoEDM apparatus at the ILL, Grenoble, and used to characterise the magnetic environment. Further tests in a suitable low noise environment confirm it meets our requirements.
The cryoEDM neutron electric dipole moment experiment requires a SQUID magnetometry system with pick-up loops inside a magnetically shielded volume connected to SQUID sensors by long (up to 2m) ...twisted-wire pairs (TWPs). These wires run outside the main shield, and therefore must run through superconducting capillaries to screen unwanted magnetic pick-up. We show that the average measured transverse magnetic pick-up of a set of lengths of TWPs is equivalent to a loop area of 5.0×10−6m2/m, or 14 twists per metre. From this we set the requirement that the magnetic shielding factor of the superconducting capillaries used in the cryoEDM system must be greater than 8.0×104. The shielding factor—the ratio of the signal picked-up by an unshielded TWP to that induced in a shielded TWP—was measured for a selection of superconducting capillaries made from solder wire. We conclude the transverse shielding factor of a uniform capillary is greater than 107. The measured pick-up was equal to, or less than that due to direct coupling to the SQUID sensor (measured without any TWP attached). We show that discontinuities in the capillaries substantially impair the magnetic shielding, yet if suitably repaired, this can be restored to the shielding factor of an unbroken capillary. We have constructed shielding assemblies for cryoEDM made from lengths of single core and triple core solder capillaries, joined by a shielded Pb cylinder, incorporating a heater to heat the wires above the superconducting transition as required.
Semi-empirical molecular orbital calculations were performed using MINDO/3 to examine the mechanism of quenching of singlet (excited) molecular oxygen by amines. Amines with reported ionization ...potentials and singlet oxygen quenching rate constants were modeled with singlet oxygen at various distances from the amine nitrogen, and the enthalpies of formation of the resultant supramolecules were graphed vs. the nitrogen-oxygen separation. Primary amines gave a distinct energy minimum at a nitrogen-oxygen separation of about 1.54 Å and a nitrogen-oxygen-oxygen “bond” angle of about 119°. The electron density at nitrogen and the distal oxygen in the minimum energy complex, relative to that in the individual molecules, indicated a substantial (approximately 0.3 esu) transfer of charge from nitrogen to oxygen, consistent with a charge transfer complex. Secondary amines showed a less distinct energy minimum at the same nitrogen-oxygen separation, whereas tertiary amines gave only an inflection point. Because a charge transfer quenching mechanism requires intersystem crossing (singlet to triplet) during complexation, the upper limit of the energy of the charge transfer complex was also calculated by specifying a triplet state. This was substantially higher in energy than the singlet complex in the case of primary and secondary amines, but slightly lower in energy for tertiary amines. This calculated upper limit for the enthalpy of activation of intersystem crossing (quenching) via a charge transfer complex correlated well (
r = −0.97) with the logarithm of the quenching rate constant for a series of amines. The close proximity (1.54 Å) required between nitrogen and oxygen in the charge transfer complex explains the sensitivity to steric hindrance in the vicinity of nitrogen observed for singlet oxygen quenching rates by aliphatic amines. These data are consistent with a charge transfer mechanism of quenching of singlet oxygen by amines.
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