Constraints on the Decay of

^{180m}Ta is a rare nuclear isomer whose decay has never been observed. Its remarkably long lifetime surpasses the half-lives of all other known ß and electron capture decays due to the large K-spin differences and small energy differences between the isomeric and lower-energy states. Detecting its decay presents a significant experimental challenge but could shed light on neutrino-induced nucleosynthesis mechanisms, the nature of dark matter, and K-spin violation. For this study, we repurposed the Majorana Demonstrator, an experimental search for the neutrinoless double-beta decay of ^{76}Ge using an array of high-purity germanium detectors, to search for the decay of ^{180m}Ta. More than 17 kg, the largest amount of tantalum metal ever used for such a search, was installed within the ultralow-background detector array. In this Letter, we present results from the first year of Ta data taking and provide an updated limit for the ^{180m}Ta half-life on the different decay channels. With new limits up to 1.5×10^{19} yr, we improved existing limits by 1-2 orders of magnitude which are the most sensitive searches for a single ß and electron capture decay ever achieved. Over all channels, the decay can be excluded for T_{1/2}<0.29×10^{18} yr.

Erratum: Search for Spontaneous Radiation from Wave Function Collapse in the Majorana Demonstrator [Phys. Rev. Lett. 129, 080401 (2022)].

This corrects the article DOI: 10.1103/PhysRevLett.129.080401.

Search for Spontaneous Radiation from Wave Function Collapse in the Majorana Demonstrator.

The Majorana Demonstrator neutrinoless double-beta decay experiment comprises a 44 kg (30 kg enriched in ^{76}Ge) array of p-type, point-contact germanium detectors. With its unprecedented energy resolution and ultralow backgrounds, Majorana also searches for rare event signatures from beyond standard model physics in the low energy region below 100 keV. In this Letter, we test the continuous spontaneous localization (CSL) model, one of the mathematically well-motivated wave function collapse models aimed at solving the long-standing unresolved quantum mechanical measurement problem. While the CSL predicts the existence of a detectable radiation signature in the x-ray domain, we find no evidence of such radiation in the 19-100 keV range in a 37.5 kg-y enriched germanium exposure collected between December 31, 2015, and November 27, 2019, with the Demonstrator. We explored both the non-mass-proportional (n-m-p) and the mass-proportional (m-p) versions of the CSL with two different assumptions: that only the quasifree electrons can emit the x-ray radiation and that the nucleus can coherently emit an amplified radiation. In all cases, we set the most stringent upper limit to date for the white CSL model on the collapse rate, λ, providing a factor of 40-100 improvement in sensitivity over comparable searches. Our limit is the most stringent for large parts of the allowed parameter space. If the result is interpreted in terms of the Diòsi-Penrose gravitational wave function collapse model, the lower bound with a 95% confidence level is almost an order of magnitude improvement over the previous best limit.

Entanglement Swapping with Photons Generated on Demand by a Quantum Dot.

Photonic entanglement swapping, the procedure of entangling photons without any direct interaction, is a fundamental test of quantum mechanics and an essential resource to the realization of quantum networks. Probabilistic sources of nonclassical light were used for seminal demonstration of entanglement swapping, but applications in quantum technologies demand push-button operation requiring single quantum emitters. This, however, turned out to be an extraordinary challenge due to the stringent prerequisites on the efficiency and purity of the generation of entangled states. Here we show a proof-of-concept demonstration of all-photonic entanglement swapping with pairs of polarization-entangled photons generated on demand by a GaAs quantum dot without spectral and temporal filtering. Moreover, we develop a theoretical model that quantitatively reproduces the experimental data and provides insights on the critical figures of merit for the performance of the swapping operation. Our theoretical analysis also indicates how to improve state-of-the-art entangled-photon sources to meet the requirements needed for implementation of quantum dots in long-distance quantum communication protocols.

InP-InxGa1-xAs core-multi-shell nanowire quantum wells with tunable emission in the 1.3-1.55 µm wavelength range.

The usability and tunability of the essential InP-InGaAs material combination in nanowire-based quantum wells (QWs) are assessed. The wurtzite phase core-multi-shell InP-InGaAs-InP nanowire QWs are characterised using cross-section transmission electron microscopy and photoluminescence measurements. The InP-InGaAs direct interface is found to be sharp while the InGaAs-InP inverted interface is more diffused, in agreement with their planar counterpart. Bright emission is observed from the single nanowires containing the QWs at room temperature, with no emission from the InP core or outer barrier. The tunability of the QW emission wavelength in the 1.3-1.55 µm communication wavelength range is demonstrated by varying the QW thickness and in the 1.3 µm range by varying the composition. The experiments are supported by simulation of the emission wavelength of the wurtzite phase InP-InGaAs QWs in the thickness range considered. The radial heterostructure is further extended to design multiple QWs with bright emission, therefore establishing the capability of this material system for nanowire based optical devices for communication applications.

Value and Anisotropy of the Electron and Hole Mass in Pure Wurtzite InP Nanowires.

The effective mass of electrons and holes in semiconductors is pivotal in determining the dynamics of carriers and their confinement energy in nanostructured materials. Surprisingly, this quantity is still unknown in wurtzite (WZ) nanowires (NWs) made of III-V compounds (e.g., GaAs, InAs, GaP, InP), where the WZ phase has no bulk counterpart. Here, we investigate the magneto-optical properties of InP WZ NWs grown by selective-area epitaxy that provides perfectly ordered NWs featuring high-crystalline quality. The combined analysis of the energy of free exciton states and impurity levels under magnetic field (B up to 29 T) allows us to disentangle the dynamics of oppositely charged carriers from the Coulomb interaction and thus to determine the values of the electron and hole effective mass. By application of B⃗ along different crystallographic directions, we also assess the dependence of the transport properties with respect to the NW growth axis (namely, the WZ c axis). The effective mass of electrons along c is me∥ = (0.078 ± 0.002) m0 (m0 is the electron mass in vacuum) and perpendicular to c is me⊥ = (0.093 ± 0.001) m0, resulting in a 20% mass anisotropy. Holes exhibit a much larger (∼320%) and opposite mass anisotropy with their effective mass along and perpendicular to c equal to mh∥ = (0.81 ± 0.18) m0 and mh⊥ = (0.250 ± 0.016) m0, respectively. While no full consensus is found with current theoretical results on WZ InP, our findings show trends remarkably similar to the experimental data available in WZ bulk materials, such as InN, GaN, and ZnO.

Long-Lived Hot Carriers in III-V Nanowires.

Heat management mechanisms play a pivotal role in driving the design of nanowire (NW)-based devices. In particular, the rate at which charge carriers cool down after an external excitation is crucial for the efficiency of solar cells, lasers, and high-speed transistors. Here, we investigate the thermalization properties of photogenerated carriers by continuous-wave (cw) photoluminescence (PL) in InP and GaAs NWs. A quantitative analysis of the PL spectra recorded up to 310 K shows that carriers can thermalize at a temperature much higher than that of the lattice. We find that the mismatch between carrier and lattice temperature, ΔT, increases exponentially with lattice temperature and depends inversely on the NW diameter. ΔT is instead independent of other NW characteristics, such as crystal structure (wurtzite vs zincblende), chemical composition (InP vs GaAs), shape (tapered vs columnar NWs), and growth method (vapor-liquid-solid vs selective-area growth). Remarkably, carrier temperatures as high as 500 K are reached at the lattice temperature of 310 K in NWs with ∼70 nm diameter. While a population of nonequilibrium carriers, usually referred to as "hot carriers", is routinely generated by high-power laser pulses and detected by ultrafast spectroscopy, it is quite remarkable that it can be observed in cw PL measurements, when a steady-state population of carriers is established. Time-resolved PL measurements show that even in the thinnest NWs carriers have enough time (∼1 ns) after photoexcitation to interact with phonons and thus to release their excess energy. Nevertheless, the inability of carriers to reach a full thermal equilibrium with the lattice points to inhibited phonon emission primarily caused by the large surface-to-volume ratio of small diameter NWs.

Abundance and genetic damage of barn swallows from Fukushima.

A number of studies have assessed or modeled the distribution of the radionuclides released by the accident at the Fukushima-Daiichi Nuclear Power Plant (FDNPP). Few studies however have investigated its consequences for the local biota. We tested whether exposure of barn swallow (Hirundo rustica) nestlings to low dose ionizing radiation increased genetic damage to their peripheral erythrocytes. We estimated external radiation exposure by using thermoluminescent dosimeters, and by measuring radioactivity of the nest material. We then assessed DNA damage by means of the neutral comet assay. In addition, we conducted standard point-count censuses of barn swallows across environmental radiation levels, and estimated their abundance and local age ratio. Radioactivity of nest samples was in the range 479-143,349 Bq kg(-1), while external exposure varied between 0.15 and 4.9 mGy. Exposure to radioactive contamination did not correlate with higher genetic damage in nestlings. However, at higher levels of radioactive contamination the number of barn swallows declined and the fraction of juveniles decreased, indicating lower survival and lower reproduction and/or fledging rate. Thus, genetic damage to nestlings does not explain the decline of barn swallows in contaminated areas, and a proximate mechanism for the demographic effects documented here remains to be clarified.

SU-E-T-389: Accuracy of a VMAT Planning System for Head and Neck Radiotherapy.

PURPOSE: To determine the accuracy of VMAT treatment planning and delivery for patients undergoing radiotherapy in the head and neck. METHOD AND MATERIALS: A dosimetric study of a typical head and neck treatment plan has been carried out using Chamber, film and TLD's placed inside an anthropomorphic phantom. Lateral and AP port films were taken to verify the isocenter prior to treatment. Multiple treatments were performed to assess the reproducibility and uncertainty in the TLD measurements. Gafchromatic film was used between the phantom slices and then analyzed as an independent check on the TLD results. The two data sets, from TLDs and films, were then compared with the treatment planning system dose calculations. RESULTS: The measured dose to the primary planning tumor volume agrees with the planning system within 2%. The comparison of the measured dose to the secondary tumor volume ranges from 3-6% and the spinal cord comparison ranges from 3-10%. CONCLUSION: This new Smart Arc treatment, VMAT, has great benefits to the patient in that patient motion and internal motion of the tumor is dramatically reduced. Challenges arise in predicting the dose near heterogeneities between the treatment planning system and actual measurement.

SU-F-BRCD-03: Dose Calculation of Electron Therapy Using Improved Lateral Buildup Ratio Method.

PURPOSE: To calculate the percentage depth dose of any irregular shape electron beam using modified lateral build-up-ratio method. METHOD AND MATERIALS: Percentage depth dose (PDD) curves were measured using 6, 9, 12, and 15MeV electron beam energies for applicator cone sizes of 6×6, 10×10, 14×14, and 14×14cm2 . Circular cutouts for each cone were prepared from 2.0cm diameter to the maximum possible size for each cone. In addition, three irregular cutouts were prepared. The scanning was done using a water tank and two diodes - one for the signal and the other a stationary reference outside the tank. The water surface was determined by scanning the signal diode slowly from water to air and by noting the sharp change of the percentage depth dose curve at the water/air interface. RESULTS: The lateral build-up-ratio (LBR) for each circular cutout was calculated from the measured PDD curve using the open field of the 14×14 cm2 cone as the reference field. Using the LBR values and the radius of the circular cutouts, the corresponding lateral spread parameter (sigma) of the electron shower was calculated. Unlike the commonly accepted assumption that sigma is independent of cutout size, it is shown that the sigma value increases linearly with circular cutout size. Using this characteristic of sigma, the PDD curves of irregularly shaped cutouts were calculated. Finally, the calculated PDD curves were compared with measured PDD curves. CONCLUSIONS: In this research, it is shown that sigma increases with cutout size. For radius of circular cutout sizes up to the equilibrium range of the electron beam, the increase of sigma with the cutout size is linear. The percentage difference of the calculated PDD from the measured PDD for irregularly shaped cutouts was under 1.0%. Similar Result was obtained for four electron beam energies (6, 9, 12, and 15MeV).

Pregabalin in outpatient detoxification of subjects with mild-to-moderate alcohol withdrawal syndrome.

OBJECTIVE: In this open, prospective study we aimed to investigate the efficacy, medical safety and practicability of pregabalin in outpatient detoxification of alcohol-dependent patients with mild-to-moderate alcohol withdrawal syndrome (AWS). Craving reduction, improvement of psychiatric symptoms and quality of life were the secondary endpoints. METHODS: Forty alcohol dependent patients (DSM-IV) were detoxified receiving 200-450 mg of pregabalin. Withdrawal (Clinical Institute Withdrawal Assessment for Alcohol (CIWA-Ar)) and craving (Visual Analogue Scale (VAS); Obsessive and Compulsive Drinking Scale (OCDS)) rating scales were applied; psychiatric symptoms and quality of life were evaluated using the Symptom Check List-90 Revised (SCL-90-R) and the QL-Index, respectively. Relapsed and abstinent patients in the post-detoxification evaluation have been compared. RESULTS: Alcohol withdrawal symptoms and craving for alcohol resulted significantly reduced (p < 0.001) over time after pregabalin treatment. Pregabalin also resulted in a favourable improvement in psychiatric symptoms and quality of life (p < 0.001). CONCLUSIONS: To our knowledge, this is the first open, prospective study, about the possible use of pregabalin as an outpatient detoxification agent. These preliminary data show its efficacy and safety in the management of patients with mild-to-moderate AWS.

Pregabalin versus naltrexone in alcohol dependence: a randomised, double-blind, comparison trial.

Pregabalin (PRE) acts as a presynaptic inhibitor of the release of excessive levels of excitatory neurotransmitters by selectively binding to the alpha(2)-delta subunit of voltage-gated calcium channels. In this randomised, double-blind comparison trial with naltrexone (NAL), we aimed to investigate the efficacy of PRE on alcohol drinking indices. Craving reduction and improvement of psychiatric symptoms were the secondary endpoints. Seventy-one alcohol-dependent subjects were detoxified and subsequently randomised into two groups, receiving 50 mg of NAL or 150-450 mg of PRE. Craving (VAS; OCDS), withdrawal (CIWA-Ar) and psychiatric symptoms (SCL-90-R) rating scales were applied. Alcohol drinking indices and craving scores were not significantly different between groups. Compared with NAL, PRE resulted in greater improvement of specific symptoms in the areas of anxiety, hostility and psychoticism, and survival function (duration of abstinence from alcohol). PRE also resulted in better outcome in patients reporting a comorbid psychiatric disorder. Results from this study globally place PRE within the same range of efficacy as that of NAL. The mechanism involved in the efficacy of PRE in relapse prevention could be less related to alcohol craving and more associated with the treatment of the comorbid psychiatric symptomatology.

Mono- and polysubstance dependent subjects differ on social factors, childhood trauma, personality, suicidal behaviour, and comorbid Axis I diagnoses.

BACKGROUND: The study aimed to examine the clinical correlates of polysubstance dependence. SUBJECTS AND METHODS: Seven hundred and fifty two substance-dependent subjects were interviewed with the Mini-International Neuropsychiatric Interview, the Brown-Goodwin Assessment for Lifetime History of Aggression (BGLHA), and the Hamilton Depression Rating Scale (HDRS). Subjects completed the Childhood Trauma Questionnaire (CTQ), Eysenck Personality Questionnaire (EPQ), and Barratt Impulsivity Scale (BIS). Subjects found to have polysubstance dependence were compared with subjects with monosubstance dependence. RESULTS: Polysubstance dependence was found in 48.3% of the subjects. Subjects with polysubstance dependence were significantly younger, more were separated/divorced and unemployed, and they had significantly higher CTQ scores for childhood emotional and physical neglect, higher EPQ psychoticism scores, higher BGLHA aggression scores, and higher BIS impulsivity scores. Significantly more of the polysubstance dependent subjects had attempted suicide, self-mutilated, and exhibited aggressive behavior. Significantly more monosubstance dependent subjects had an Axis I psychiatric disorder and they had higher HDRS depression scores. CONCLUSIONS: Polysubstance dependence is common among the groups studied and may be associated with certain socio-demographic, developmental, and personality factors.

Cocaine use disorders and serum magnesium profile.

INTRODUCTION: Magnesium influences the nervous system via its actions on the release and metabolism of neurotransmitters, and abnormal magnesium metabolism has been implicated in several neuropsychiatric disorders with prominent mood symptoms. The aim of this study was to compare the serum levels of magnesium of cocaine addicts to those of heroin addicts and normal controls. We also attempted to clarify the relationship between the pathophysiology of cocaine abuse and magnesium levels by investigating their association with various clinical dimensions. METHODS: Eighty-five consecutive subjects with a history of cocaine or opiate use disorders were recruited, evaluated and compared with 100 controls. The cocaine and heroin abusers were assessed with a 10-cm Visual Analogue Scale, the Symptom Check List-90 Revised, the Brown-Goodwin Scale, and the Barrat Impulsiveness Scale. RESULTS: Magnesium levels were higher in the cocaine group compared to the opiate group and control. Male subjects had lower magnesium levels than the females of all three groups. Scores of impulsiveness, aggressiveness, craving and psychiatric symptomatology were not significantly different between the opiate and cocaine addicts. DISCUSSION: This is the first study evaluating the magnesium level in cocaine addicts. Cocaine addicts showed higher total plasma magnesium levels than opiate addicts and normal controls, even though they remained in the normal range. The roles of the psychiatric comorbidity, of a pharmacokinetic association and of a pharmacodynamic interaction are discussed. Further prospective studies comparing serum levels of cocaine at different times are needed.

Search for the Theta+ Pentaquark in the gammad--> DeltanK+ reaction measured with the CLAS spectrometer.

For the first time, the reaction gammad-->DeltanK+ has been analyzed in order to search for the exotic pentaquark baryon Theta+(1540). The data were taken at Jefferson Laboratory, using the Hall-B tagged-photon beam of energy between 0.8 and 3.6 GeV and the CEBAF Large Acceptance Spectrometer (CLAS). No statistically significant structures were observed in the nK+ invariant-mass distribution. The upper limit on the gammad-->DeltaTheta+ integrated cross section has been calculated and found to be between 5 and 25 nb, depending on the production model assumed. The upper limit on the differential cross section is also reported.

Search for the Theta+ pentaquark in the reaction gammad --> pK-K+n.

A search for the Theta+ in the reaction gammad --> pK-K+n was completed using the CLAS detector at Jefferson Lab. A study of the same reaction, published earlier, reported the observation of a narrow Theta+ resonance. The present experiment, with more than 30 times the integrated luminosity of our earlier measurement, does not show any evidence for a narrow pentaquark resonance. The angle-integrated upper limit on Theta+ production in the mass range of 1.52-1.56 GeV/c2 for the gammad --> pK-Theta+ reaction is 0.3 nb (95% C.L.). This upper limit depends on assumptions made for the mass and angular distribution of Theta+ production. Using Lambda(1520) production as an empirical measure of rescattering in the deuteron, the cross section upper limit for the elementary gamman --> K-Theta+ reaction is estimated to be a factor of 10 higher, i.e., approximately 3 nb (95% C.L.).

Observation of an exotic S = +1 baryon in exclusive photoproduction from the deuteron.

In an exclusive measurement of the reaction gammad-->K(+)K(-)pn, a narrow peak that can be attributed to an exotic baryon with strangeness S=+1 is seen in the K(+)n invariant mass spectrum. The peak is at 1.542+/-0.005 GeV/c(2) with a measured width of 0.021 GeV/c(2) FWHM, which is largely determined by experimental mass resolution. The statistical significance of the peak is (5.2+/-0.6)sigma. The mass and width of the observed peak are consistent with recent reports of a narrow S=+1 baryon by other experimental groups.

Coenzyme Q10 levels in pigeon (Columba livia) spermatozoa.

AIM: To assess the CoQ10 levels in pigeon spermatozoa and to verify their possible correlation with spermatic kinetic parameters. METHODS: In pigeons the sperm motility percentage (MOT%), mean linear velocity (VCM) and morphology were determined in ejaculated semen. In addition intracellular CoQ10 concentrations were also detected with a HPLC method. RESULTS: Intracellular CoQ10 levels demonstrated wide individual variations, averaging 4.85 +/- 2.31 (SD) ng/106 spermatozoa. Statistical analysis showed a positive correlation of the substance with the sperm concentration (r= 0.63; P<0.05) and with the VCM (r=0.66; P<0.05), and a negative correlation with the MOT% (r = -0.78; P=0.01). No correlation was found between the CoQ10 concentration and the percentage of normal spermatozoa. CONCLUSION: Our results suggest a possible role for CoQ10 as a "fertility marker" in pigeons, which may be employed to monitor the pharmacological effects of cytostatic substances often used to reduce the pigeon fertility in urban environment.

Application of a constant blood withdrawal method in equine exercise physiology studies.

The aim of the present study was to test a constant blood withdrawal method (CBWM) to collect blood samples from horses during treadmill exercise. CBWM was performed in 4 Standardbreds and 5 Haflinger horses. A peristaltic pump was used to control blood aspiration from an i.v. catheter via an extension line. Blood was collected using an automatic fractions collector, with a constant delay time between the drawing of blood and sample collection. Blood withdrawal using CBWM was made during a treadmill standardised exercise test (SET). A blood flow of 12 m/min was used and samples collected every 60 s during the entire period of exercise. The volume of blood collected in each sample tube was 12.1+/-0.2 ml, with a delay time of mean +/- s.d. 25.3+/-0.8 s. Plasma lactate kinetics based on measurement of lactate in each fraction showed an exponential increase during the first 13 min of exercise (10.5 min of SET and 2.5 min recovery). The peak plasma lactate concentration was observed between 2.5 and 5.5 min after the end of SET. CBWM permits the kinetics of lactate and other blood-borne variables to be studied over time. This method could be a valuable aid for use in studying equine exercise physiology.

Coenzyme Q10, exercise lactate and CTG trinucleotide expansion in myotonic dystrophy.

Steinert's myotonic dystrophy (DM) is a genetic autosomal dominant disease and the most frequent muscular dystrophy in adulthood. Although causative mutation is recognized as a CTG trinucleotide expansion on 19q13.3, pathogenic mechanisms of multisystem involvement of DM are still under debate. It has been suggested that mitochondrial abnormalities can occur in this disease and deficiency of coenzyme Q 10 (CoQ10) has been considered one possible cause for this. The aim of this investigation was to evaluate, in 35 DM patients, CoQ10 blood levels and relate them to the degree of CTG expansion as well as to the amount of lactate production in exercising muscle as indicator of mitochondrial dysfunction. CoQ10 concentrations appeared significantly reduced with respect to normal controls: 0.85 +/- 0.25 vs. 1.58 +/- 0.28 microg/ml (p < 0.05). Mean values of blood lactate were significantly higher in DM patients than controls (p < 0.05) both in resting conditions (2.9 +/- 0.55 vs. 1.44 +/- 1.11 mmol/L) and at the exercise peak (6.77 +/- 1.79 vs. 4.90 +/- 0.59 mmol/L), while exercise lactate threshold was anticipated (30-50% vs. 60-70% of the predicted normal maximal power output, p < 0.05). Statistical analysis showed that serum CoQ10 levels were significantly (p < 0.05) inversely correlated with both CTG expansion degree and lactate values at exercise lactate threshold level. Our data indicates the occurrence of reduced CoQ10 levels in DM, possibly related to disease pathogenic mechanisms associated with abnormal CTG trinucleotide amplification.