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Many extensions of the standard model of particle physics suggest that neutrinos should be Majorana-type fermions—that is, that neutrinos are their own anti-particles—but this assumption is difficult to confirm. Observation of neutrinoless double-β decay (0 νββ ), a spontaneous transition that may occur in several candidate nuclei, would verify the Majorana nature of the neutrino and constrain the absolute scale of the neutrino mass spectrum. Recent searches carried out with 76 Ge (the GERDA experiment) and 136 Xe (the KamLAND-Zen and EXO (Enriched Xenon Observatory)-200 experiments) have established the lifetime of this decay to be longer than 10 25  years, corresponding to a limit on the neutrino mass of 0.2–0.4 electronvolts. Here we report new results from EXO-200 based on a large 136 Xe exposure that represents an almost fourfold increase from our earlier published data sets. We have improved the detector resolution and revised the data analysis. The half-life sensitivity we obtain is 1.9 × 10 25  years, an improvement by a factor of 2.7 on previous EXO-200 results. We find no statistically significant evidence for 0 νββ decay and set a half-life limit of 1.1 × 10 25  years at the 90 per cent confidence level. The high sensitivity holds promise for further running of the EXO-200 detector and future 0 νββ decay searches with an improved Xe-based experiment, nEXO. Neutrinos are known to have mass, in contradiction to the predictions of the standard model, and one explanation of this mass is that they are Majorana fermions; this conjecture could be proved by observation of the neutrinoless double-β decay process, but new experiments with 136 Xe find no statistically significant evidence for this process. Neutrino mass limited Neutrinos are curious particles. According to the standard model of particle physics they should be massless. Yet experiments show that they do have a mass, which can be explained naturally if neutrinos are assumed to be Majorana fermions — particles that are their own anti-particles. One way to prove this conjecture would be the observation of neutrinoless double-β decay, a nuclear process that can occur in several different nuclei. Here, the authors set a half-life limit of 1.1 × 10 25 years for this process in the noble-gas isotope xenon-136 based on new high-exposure data from the EXO-200 detector. Their limit establishes xenon-136 as an important test bed for the search for neutrinoless double-β decay.

Astrophysical observations indicate that dark matter constitutes most of the mass in our universe, but its nature remains unknown. Over the past decade, the Cryogenic Dark Matter Search (CDMS II) experiment has provided world-leading sensitivity for the direct detection of weakly interacting massive particle (WIMP) dark matter. The final exposure of our low-temperature germanium particle detectors at the Soudan Underground Laboratory yielded two candidate events, with an expected background of 0.9 ± 0.2 events. This is not statistically significant evidence for a WIMP signal. The combined CDMS II data place the strongest constraints on the WIMP-nucleon spin-independent scattering cross section for a wide range of WIMP masses and exclude new parameter space in inelastic dark matter models.

X‐ray free‐electron lasers (XFELs) deliver pulses of coherent X‐rays on the femtosecond time scale, with potentially high repetition rates. While XFELs provide high peak intensities, both the intensity and the centroid of the beam fluctuate strongly on a pulse‐to‐pulse basis, motivating high‐rate beam diagnostics that operate over a large dynamic range. The fast drift velocity, low X‐ray absorption and high radiation tolerance properties of chemical vapour deposition diamonds make these crystals a promising candidate material for developing a fast (multi‐GHz) pass‐through diagnostic for the next generation of XFELs. A new approach to the design of a diamond sensor signal path is presented, along with associated characterization studies performed in the XPP endstation of the LINAC Coherent Light Source (LCLS) at SLAC. Qualitative charge collection profiles (collected charge versus time) are presented and compared with those from a commercially available detector. Quantitative results on the charge collection efficiency and signal collection times are presented over a range of approximately four orders of magnitude in the generated electron–hole plasma density. Two approaches to the design of a diamond sensor signal path were explored using high‐intensity X‐ray pulses from the LINAC Coherent Light Source at SLAC. Results on the charge‐collection efficiency and signal collection time are presented over a range of approximately four orders of magnitude in the generated electron–hole plasma density.

The Maya archaeological site at Colha in northern Belize, Central America, has yielded several spouted ceramic vessels that contain residues from the preparation of food and beverages. Here we analyse dry residue samples by using high-performance liquid chromatography coupled to atmospheric-pressure chemical-ionization mass spectrometry, and show that chocolate (Theobroma cacao) was consumed by the Preclassic Maya as early as 600 bc, pushing back the earliest chemical evidence of cacao use by some 1,000 years. Our application of this new and highly sensitive analytical technique could be extended to the identification of other ancient foods and beverages.

In a broad range of species—including humans—it has been demonstrated that telomere length declines throughout life and that it may be involved in cell and organismal senescence. This potential link to ageing and thus to fitness has triggered recent interest in understanding how variation in telomere length is inherited and maintained. However, previous studies suffer from two main drawbacks that limit the possibility of understanding the relative importance of genetic, parental and environmental influences on telomere length variation. These studies have been based on (i) telomere lengths measured at different time points in different individuals, despite the fact that telomere length changes over life, and (ii) parent–offspring regression techniques, which do not enable differentiation between genetic and parental components of inheritance. To overcome these drawbacks, in our study of a songbird, the great reed warbler, we have analysed telomere length measured early in life in both parents and offspring and applied statistical models (so-called ‘animal models') that are based on long-term pedigree data. Our results showed a significant heritability of telomere length on the maternal but not on the paternal side, and that the mother's age was positively correlated with their offspring's telomere length. Furthermore, the pedigree-based analyses revealed a significant heritability and an equally large maternal effect. Our study demonstrates strong maternal influence on telomere length and future studies now need to elucidate possible underlying factors, including which types of maternal effects are involved.

Spouted vessels are diagnostic forms of Middle Preclassic (1000–400 B. C.) and Late Preclassic (400 B. C.-A. D. 250) Maya ceramic assemblages. Mayanists have traditionally called these vessels “chocolate pots,” but until recently there has been little direct evidence to support this interpretation. In fact, few studies have focused on the role these specialized forms played in the daily social and ritual activities of the ancient Maya. This paper provides a contextual and functional analysis of Preclassic spouted vessels found across the Maya lowlands and highlands. Additionally, the results of chemical analyses on residues collected from spouted vessels found in Middle and Late Preclassic burials at Colha, Belize are provided. Preliminary data reveal that some of the vessels from Colha contained substantial amounts of theobromine, a distinct marker for cacao or chocolate. The significance of the discovery of chocolate in Maya spouted vessels is discussed as well as its implications for the rest of Mesoamerica.

The Gerda experiment located at the Laboratori Nazionali del Gran Sasso of INFN searches for neutrinoless double beta (0 νββ ) decay of 76 Ge using germanium diodes as source and detector. In Phase I of the experiment eight semi-coaxial and five BEGe type detectors have been deployed. The latter type is used in this field of research for the first time. All detectors are made from material with enriched 76 Ge fraction. The experimental sensitivity can be improved by analyzing the pulse shape of the detector signals with the aim to reject background events. This paper documents the algorithms developed before the data of Phase I were unblinded. The double escape peak (DEP) and Compton edge events of 2.615 MeV γ rays from 208 Tl decays as well as two-neutrino double beta (2 νββ ) decays of 76 Ge are used as proxies for 0 νββ decay. For BEGe detectors the chosen selection is based on a single pulse shape parameter. It accepts 0.92±0.02 of signal-like events while about 80 % of the background events at Q ββ =2039 keV are rejected. For semi-coaxial detectors three analyses are developed. The one based on an artificial neural network is used for the search of 0 νββ decay. It retains 90 % of DEP events and rejects about half of the events around Q ββ . The 2 νββ events have an efficiency of 0.85±0.02 and the one for 0 νββ decays is estimated to be . A second analysis uses a likelihood approach trained on Compton edge events. The third approach uses two pulse shape parameters. The latter two methods confirm the classification of the neural network since about 90 % of the data events rejected by the neural network are also removed by both of them. In general, the selection efficiency extracted from DEP events agrees well with those determined from Compton edge events or from 2 νββ decays.

The GERmanium Detector Array ( Gerda ) experiment at the Gran Sasso underground laboratory (LNGS) of INFN is searching for neutrinoless double beta ( 0 ν β β ) decay of 76 Ge. The signature of the signal is a monoenergetic peak at 2039 keV, the Q β β value of the decay. To avoid bias in the signal search, the present analysis does not consider all those events, that fall in a 40 keV wide region centered around Q β β . The main parameters needed for the 0 ν β β analysis are described. A background model was developed to describe the observed energy spectrum. The model contains several contributions, that are expected on the basis of material screening or that are established by the observation of characteristic structures in the energy spectrum. The model predicts a flat energy spectrum for the blinding window around Q β β with a background index ranging from 17.6 to 23.8  ×   10 - 3  cts/(keV kg yr). A part of the data not considered before has been used to test if the predictions of the background model are consistent. The observed number of events in this energy region is consistent with the background model. The background at Q β β is dominated by close sources, mainly due to 42 K, 214 Bi, 228 Th, 60 Co and α emitting isotopes from the 226 Ra decay chain. The individual fractions depend on the assumed locations of the contaminants. It is shown, that after removal of the known γ peaks, the energy spectrum can be fitted in an energy range of 200 keV around Q β β with a constant background. This gives a background index consistent with the full model and uncertainties of the same size.

The Maya archaeological site at Colha in northern Belize, Central America, has yielded several spouted ceramic vessels that contain residues from the preparation of food and beverages. Here we analyse dry residue samples by using high-performance liquid chromatography coupled to atmospheric-pressure chemical-ionization mass spectrometry, and show that chocolate (Theobroma cacao) was consumed by the Preclassic Maya as early as 600 bc, pushing back the earliest chemical evidence of cacao use by some 1,000 years. Our application of this new and highly sensitive analytical technique could be extended to the identification of other ancient foods and beverages.

Category: Sports; Trauma Introduction/Purpose: Randomized controlled trials of surgery versus nonoperative management of Achilles ruptures have been numerous but relatively small. A recent large RCT, published in the New England Journal of Medicine by Myhrvold and coauthors, addressed this with 554 patients enrolled in 3 arms: nonoperative, open surgery, and minimally invasive surgery. The authors found no difference between groups in the primary outcome, the validated Achilles Tendon Rupture Score (ATRS), but a significantly higher rate of rerupture in the nonoperative group (6.2% vs. 0.6% vs 0.6%). The online trial protocol indicates that patients who suffered a rerupture were excluded from further data collection and analysis, but those who had surgical infections and nerve injuries were not. This selective data censoring may have biased the trial outcome against surgery. Methods: To determine if the potential effect from excluding reruptures from final analysis was numerically sufficient to alter the trial results, data models were generated by Monte Carlo analysis using the pre- and post-intervention ATRS score means and standard deviations as ground truths. A model was created of all three groups at their original size. The previously excluded rerupture patients were then added back in at an assumed ATRS score. The original statistical methods of the RCT were used to determine any between-group differences. The analysis was repeated 100,000 times for each possible ATRS score for the rerupture patients. Results: The MCID for the ATRS score is 10 points. Repeated trials analysis found that when rerupture patients were added back into the groups at an assumed ATRS score equal to the reported final mean for nonoperatively treated patients (76), the percentage of model trials that had outcomes favoring a surgical group over nonoperative treatment was 7.9%. This baseline model inherently assumes there is no dysfunction associated with a rerupture. When rerupture was assumed to have associated dysfunction, the percentage of model trials that had outcomes favoring surgery to statistical significance increased as the assumed degree of dysfunction was increased: Rerupture ATRS scores at 1 MCID below nonoperative mean (66): 13.7% Rerupture ATRS scores at 2 MCID’s below nonoperative mean (56): 22.0% Conclusion: Rerupture is almost exclusively a complication of nonoperative treatment. By excluding rerupture patients from further data collection and analysis, the protocol eliminated the likely worst outcomes from the nonoperative treatment while retaining the likely worst outcomes from surgery. While the RCT reported no difference between groups at p<.05, Monte Carlo modeling indicates that at reasonable assumed values of ATRS scores for rerupture patients, the effect of excluding rerupture patients from analysis was potentially large enough to bias the primary trial outcome against surgery. Future trials that follow all patients through their entire treatment course regardless of complications will be required.