Search for Daily Modulation of MeV Dark Matter Signals with DAMIC-M.

Dark matter (DM) particles with sufficiently large cross sections may scatter as they travel through Earth's bulk. The corresponding changes in the DM flux give rise to a characteristic daily modulation signal in detectors sensitive to DM-electron interactions. Here, we report results obtained from the first underground operation of the DAMIC-M prototype detector searching for such a signal from DM with MeV-scale mass. A model-independent analysis finds no modulation in the rate of 1 e^{-} events with sidereal period, where a DM signal would appear. We then use these data to place exclusion limits on DM in the mass range [0.53,2.7] MeV/c^{2} interacting with electrons via a dark photon mediator. Taking advantage of the time-dependent signal we improve by ∼2 orders of magnitude on our previous limit obtained from the total rate of 1 e^{-} events, using the same dataset. This daily modulation search represents the current strongest limit on DM-electron scattering via ultralight mediators for DM masses around 1 MeV/c^{2}.

First Constraints from DAMIC-M on Sub-GeV Dark-Matter Particles Interacting with Electrons.

We report constraints on sub-GeV dark matter particles interacting with electrons from the first underground operation of DAMIC-M detectors. The search is performed with an integrated exposure of 85.23 g days, and exploits the subelectron charge resolution and low level of dark current of DAMIC-M charge-coupled devices (CCDs). Dark-matter-induced ionization signals above the detector dark current are searched for in CCD pixels with charge up to 7e^{-}. With this dataset we place limits on dark matter particles of mass between 0.53 and 1000 MeV/c^{2}, excluding unexplored regions of parameter space in the mass ranges [1.6,1000] MeV/c^{2} and [1.5,15.1] MeV/c^{2} for ultralight and heavy mediator interactions, respectively.

Lessons from the use of telemedicine in the austere military environment and the implications for deployed surgical teams.

Over the last 20 years, there have been significant changes in UK surgical training. Civilian surgical training may no longer prepare military surgeons for the range of skills they require on operations. One method to address gaps in knowledge or experience is to use telemedicine to facilitate specialist consultations from UK-based specialists to deployed medical teams. In the UK Defence Medical Services (DMS), this capability is called real-time clinical support (RTCS). RTCS provides a direct audio-visual link from a deployed location anywhere in the world to a supporting medical specialist in the UK. RTCS is currently delivered via a combination of off-the-shelf hardware and commercially available software. This article will outline the current use of RTCS, with emphasis on deployed surgical teams in austere environments, and discuss the advantages and limitations of this capability. However, it must be emphasised that no technology can be a substitute for clinical training and experience. Although several limitations remain, the authors believe that RTCS offers potential benefits for the DMS and could be an important tool aiding deployed clinicians. It can also be argued that by engaging with the concept now, the DMS can shape future developments in this sphere.

Unveiling contextual realities by microscopically entangling a neutron.

The development of qualitatively new measurement capabilities is often a prerequisite for critical scientific and technological advances. Here we introduce an unconventional quantum probe, an entangled neutron beam, where individual neutrons can be entangled in spin, trajectory and energy. The spatial separation of trajectories from nanometers to microns and energy differences from peV to neV will enable investigations of microscopic magnetic correlations in systems with strongly entangled phases, such as those believed to emerge in unconventional superconductors. We develop an interferometer to prove entanglement of these distinguishable properties of the neutron beam by observing clear violations of both Clauser-Horne-Shimony-Holt and Mermin contextuality inequalities in the same experimental setup. Our work opens a pathway to a future of entangled neutron scattering in matter.

Results on Low-Mass Weakly Interacting Massive Particles from an 11 kg d Target Exposure of DAMIC at SNOLAB.

We present constraints on the existence of weakly interacting massive particles (WIMPs) from an 11 kg d target exposure of the DAMIC experiment at the SNOLAB underground laboratory. The observed energy spectrum and spatial distribution of ionization events with electron-equivalent energies >200 eV_{ee} in the DAMIC CCDs are consistent with backgrounds from natural radioactivity. An excess of ionization events is observed above the analysis threshold of 50 eV_{ee}. While the origin of this low-energy excess requires further investigation, our data exclude spin-independent WIMP-nucleon scattering cross sections σ_{χ-n} as low as 3×10^{-41} cm^{2} for WIMPs with masses m_{χ} from 7 to 10 GeV c^{-2}. These results are the strongest constraints from a silicon target on the existence of WIMPs with m_{χ}<9 GeV c^{-2} and are directly relevant to any dark matter interpretation of the excess of nuclear-recoil events observed by the CDMS silicon experiment in 2013.

Constraints on Light Dark Matter Particles Interacting with Electrons from DAMIC at SNOLAB.

We report direct-detection constraints on light dark matter particles interacting with electrons. The results are based on a method that exploits the extremely low levels of leakage current of the DAMIC detector at SNOLAB of 2-6×10^{-22} A cm^{-2}. We evaluate the charge distribution of pixels that collect <10e^{-} for contributions beyond the leakage current that may be attributed to dark matter interactions. Constraints are placed on so-far unexplored parameter space for dark matter masses between 0.6 and 100 MeV c^{-2}. We also present new constraints on hidden-photon dark matter with masses in the range 1.2-30 eV c^{-2}.

A defined, plant-based diet as a potential therapeutic approach in the treatment of heart failure: A clinical case series.

BACKGROUND: Individuals diagnosed with congestive heart failure (CHF) have a 50% five-year mortality rate and approximately 650,000 new cases of CHF are diagnosed annually. Plant-based diets are known to improve plasma lipid concentrations, reduce blood pressure, and as part of a lifestyle intervention, lead to the regression of atherosclerotic lesions. However, a paucity of data exists with regards to plant-based diets in the treatment of CHF. METHODS: Three patients diagnosed with CHF opted to undergo a dietary intervention consisting of a defined plant-based diet as an adjunct to standard medical treatment for CHF. Cardiac magnetic resonance imaging was performed. Patients' consumed the defined plant-based diet for an average of ˜79 days. RESULTS: Follow-up cardiac magnetic resonance images revealed a 92% increase in ejection fraction [mean ±â€¯standard deviation for all data] (22.0 ±â€¯6.9% vs 42.2 ±â€¯18.4%), 21% reduction in left ventricular mass (214 ±â€¯90 g vs 170 ±â€¯102 g), 62% increase in stroke volume (55.8 ±â€¯24.3 cc vs 90.3 ±â€¯30.6 cc) and a 17% increase in cardiac output (3.6 ±â€¯1.2 L/min vs 4.2 ±â€¯1.6 L/min). In patient 1, 90-95% ostial stenosis of the left anterior descending artery nearly completely regressed following the dietary intervention. All patients subjectively reported significant clinical improvements, including less angina, shortness of breath and fatigue. CONCLUSION: As an adjunct treatment, a defined plant-based diet may contribute to the reversal of cardiac morphological and functional abnormalities in the setting of CHF.

Consumption of a defined, plant-based diet reduces lipoprotein(a), inflammation, and other atherogenic lipoproteins and particles within 4 weeks.

BACKGROUND: Lipoprotein(a) [Lp(a)] is a highly atherogenic lipoprotein and is minimally effected by lifestyle changes. While some drugs can reduce Lp(a), diet has not consistently shown definitive reduction of this biomarker. The effect of consuming a plant-based diet on serum Lp(a) concentrations have not been previously evaluated. HYPOTHESIS: Consumption of a defined, plant-based for 4 weeks reduces Lp(a). METHODS: Secondary analysis of a previous trial was conducted, in which overweight and obese individuals (n = 31) with low-density lipoprotein cholesterol concentrations >100 mg/dL consumed a defined, plant-based diet for 4 weeks. Baseline and 4-week labs were collected. Data were analyzed using a paired samples t-test. RESULTS: Significant reductions were observed for serum Lp(a) (-32.0 ± 52.3 nmol/L, P = 0.003), apolipoprotein B (-13.2 ± 18.3 mg/dL, P < 0.0005), low-density lipoprotein (LDL) particles (-304.8 ± 363.0 nmol/L, P < 0.0005) and small-dense LDL cholesterol (-10.0 ± 9.2 mg/dL, P < 0.0005). Additionally, serum interleukin-6 (IL-6), total white blood cells, lipoprotein-associated phospholipase A2 (Lp-PLA2), high-sensitivity c-reactive protein (hs-CRP), and fibrinogen were significantly reduced (P ≤ 0.004). CONCLUSIONS: A defined, plant-based diet has a favorable impact on Lp(a), inflammatory indicators, and other atherogenic lipoproteins and particles. Lp(a) concentration was previously thought to be only minimally altered by dietary interventions. In this protocol however, a defined plant-based diet was shown to substantially reduce this biomarker. Further investigation is required to elucidate the specific mechanisms that contribute to the reductions in Lp(a) concentrations, which may include alterations in gene expression.

A defined, plant-based diet utilized in an outpatient cardiovascular clinic effectively treats hypercholesterolemia and hypertension and reduces medications.

BACKGROUND: Cardiovascular disease (CVD) is a major economic burden in the United States. CVD risk factors, particularly hypertension and hypercholesterolemia, are typically treated with drug therapy. Five-year efficacy of such drugs to prevent CVD is estimated to be 5%. Plant-based diets have emerged as effective mitigators of these risk factors. HYPOTHESIS: The implementation of a defined, plant-based diet for 4 weeks in an outpatient clinical setting may mitigate CVD risk factors and reduce patient drug burden. METHODS: Participants consumed a plant-based diet consisting of foods prepared in a defined method in accordance with a food-classification system. Participants consumed raw fruits, vegetables, seeds, and avocado. All animal products were excluded from the diet. Participant anthropometric and hemodynamic data were obtained weekly for 4 weeks. Laboratory biomarkers were collected at baseline and at 4 weeks. Medication needs were assessed weekly. Data were analyzed using paired-samples t tests and 1-way repeated-measures ANOVA. RESULTS: Significant reductions were observed for systolic (-16.6 mmHg) and diastolic (-9.1 mmHg) blood pressure (P < 0.0005), serum lipids (P ≤ 0.008), and total medication usage (P < 0.0005). Other CVD risk factors, including weight (P < 0.0005), waist circumference (P < 0.0005), heart rate (P = 0.018), insulin (P < 0.0005), glycated hemoglobin (P = 0.002), and high-sensitivity C-reactive protein (P = 0.001) were also reduced. CONCLUSION: A defined, plant-based diet can be used as an effective therapeutic strategy in the clinical setting to mitigate cardiovascular risk factors and reduce patient drug burden.

Skill sets required for the management of military head, face and neck trauma: a multidisciplinary consensus statement.

INTRODUCTION: The evolution of medical practice is resulting in increasing subspecialisation, with head, face and neck (HFN) trauma in a civilian environment usually managed by a combination of surgical specialties working as a team. However, the full combination of HFN specialties commonly available in the NHS may not be available in future UK military-led operations, necessitating the identification of a group of skill sets that could be delivered by one or more deployed surgeons. METHOD: A systematic review was undertaken to identify those surgical procedures performed to treat acute military head, face, neck and eye trauma. A multidisciplinary consensus group was convened following this with military HFN trauma expertise to define those procedures commonly required to conduct deployed, in-theatre HFN surgical combat trauma management. RESULTS: Head, face, neck and eye damage control surgical procedures were identified as comprising surgical cricothyroidotomy, cervico-facial haemorrhage control and decompression of orbital haemorrhage through lateral canthotomy. Acute in-theatre surgical skills required within 24 hours consist of wound debridement, surgical tracheostomy, decompressive craniectomy, intracranial pressure monitor placement, temporary facial fracture stabilisation for airway management or haemorrhage control and primary globe repair. Delayed in-theatre procedures required within 5 days prior to predicted evacuation encompass facial fracture fixation, delayed lateral canthotomy, evisceration, enucleation and eyelid repair. CONCLUSIONS: The identification of those skill sets required for deployment is in keeping with the General Medical Council's current drive towards credentialing consultants, by which a consultant surgeon's capabilities in particular practice areas would be defined. Limited opportunities currently exist for trainees and consultants to gain experience in the management of traumatic head, face, neck and eye injuries seen in a kinetic combat environment. Predeployment training requires that the surgical techniques described in this paper are covered and should form the curriculum of future military-specific surgical fellowships. Relevant continued professional development will be necessary to maintain required clinical competency.

A Novel Technique of Paravertebral Thoracic and Preperitoneal Analgesia Enhances Early Recovery After Oesophagectomy.

BACKGROUND: Excellent analgesia following oesophagectomy facilitates patient comfort, early extubation, physiotherapy and mobilisation, reduces post-operative complications and should enhance recovery. Thoracic epidural analgesia (TEA), the gold standard analgesic regimen for this procedure, is often associated with systemic hypotension treated with inotropes or fluid. This may compromise enhanced recovery and be complicated by anastomotic ischaemia or tissue oedema. METHODS: We report a novel analgesic regimen to reduce post-operative inotrope usage. Infusion of ropivicaine via bilateral preperitoneal and right paravertebral catheters was used. Patient-controlled epidural pethidine provided rescue analgesia (WC) (n = 21). A retrospective audit of inotrope requirement, mean pain scores, episodes of respiratory depression and excessive sedation, need for reintubation, reoperation in the first 5 post-operative days, time to mobilisation, time in intensive care, time in hospital and 30-day mortality were measured. These results were compared with those of an earlier patient group who received a thoracic epidural infusion of low-dose local anaesthetic and fentanyl (TEA) (n = 21). RESULTS: Inotrope use was reduced by 29% in the WC group (p = 0.03) and the mean intensive care stay reduced by 2.4 days (p = 0.03), as was reintubation rate (p = 0.01) and early mobilisation (p = 0.03). The pain score was comparable in both groups, and there was no difference in the other outcomes examined. CONCLUSION: The data demonstrated that it was possible to provide excellent post-oesophagectomy analgesia equivalent to thoracic epidural infusions of local anaesthetic with reduction in inotrope requirements, intensive care stay, more rapid mobilisation, facilitating enhanced recovery.

Dark Matter Search Results from the PICO-60 C_{3}F_{8} Bubble Chamber.

New results are reported from the operation of the PICO-60 dark matter detector, a bubble chamber filled with 52 kg of C_{3}F_{8} located in the SNOLAB underground laboratory. As in previous PICO bubble chambers, PICO-60 C_{3}F_{8} exhibits excellent electron recoil and alpha decay rejection, and the observed multiple-scattering neutron rate indicates a single-scatter neutron background of less than one event per month. A blind analysis of an efficiency-corrected 1167-kg day exposure at a 3.3-keV thermodynamic threshold reveals no single-scattering nuclear recoil candidates, consistent with the predicted background. These results set the most stringent direct-detection constraint to date on the weakly interacting massive particle (WIMP)-proton spin-dependent cross section at 3.4×10^{-41} cm^{2} for a 30-GeV c^{-2} WIMP, more than 1 order of magnitude improvement from previous PICO results.

First Demonstration of a Scintillating Xenon Bubble Chamber for Detecting Dark Matter and Coherent Elastic Neutrino-Nucleus Scattering.

A 30-g xenon bubble chamber, operated at Northwestern University in June and November 2016, has for the first time observed simultaneous bubble nucleation and scintillation by nuclear recoils in a superheated liquid. This chamber is instrumented with a CCD camera for near-IR bubble imaging, a solar-blind photomultiplier tube to detect 175-nm xenon scintillation light, and a piezoelectric acoustic transducer to detect the ultrasonic emission from a growing bubble. The time of nucleation determined from the acoustic signal is used to correlate specific scintillation pulses with bubble-nucleating events. We report on data from this chamber for thermodynamic "Seitz" thresholds from 4.2 to 15.0 keV. The observed single- and multiple-bubble rates when exposed to a ^{252}Cf neutron source indicate that, for an 8.3-keV thermodynamic threshold, the minimum nuclear recoil energy required to nucleate a bubble is 19±6 keV (1σ uncertainty). This is consistent with the observed scintillation spectrum for bubble-nucleating events. We see no evidence for bubble nucleation by gamma rays at any of the thresholds studied, setting a 90% C.L. upper limit of 6.3×10^{-7} bubbles per gamma interaction at a 4.2-keV thermodynamic threshold. This indicates stronger gamma discrimination than in CF_{3}I bubble chambers, supporting the hypothesis that scintillation production suppresses bubble nucleation by electron recoils, while nuclear recoils nucleate bubbles as usual. These measurements establish the noble-liquid bubble chamber as a promising new technology for the detection of weakly interacting massive particle dark matter and coherent elastic neutrino-nucleus scattering.

Compact spherical neutron polarimeter using high-T(c) YBCO films.

We describe a simple, compact device for spherical neutron polarimetry measurements at small neutron scattering angles. The device consists of a sample chamber with very low (<0.01 G) magnetic field flanked by regions within which the neutron polarization can be manipulated in a controlled manner. This allows any selected initial and final polarization direction of the neutrons to be obtained. We have constructed a prototype device using high-T(c) superconducting films and mu-metal to isolate regions with different magnetic fields and tested device performance in transmission geometry. Finite-element methods were used to simulate the device's field profile and these have been verified by experiment using a small solenoid as a test sample. Measurements are reported using both monochromatic and polychromatic neutron sources. The results show that the device is capable of extracting sample information and distinguishing small angular variations of the sample magnetic field. As a more realistic test, we present results on the characterization of a 10 µm thick Permalloy film in zero magnetic field, as well as its response to an external magnetic field.

Dark Matter Search Results from the PICO-2L C3F8 Bubble Chamber.

New data are reported from the operation of a 2 liter C3F8 bubble chamber in the SNOLAB underground laboratory, with a total exposure of 211.5 kg days at four different energy thresholds below 10 keV. These data show that C3F8 provides excellent electron-recoil and alpha rejection capabilities at very low thresholds. The chamber exhibits an electron-recoil sensitivity of <3.5×10(-10) and an alpha rejection factor of >98.2%. These data also include the first observation of a dependence of acoustic signal on alpha energy. Twelve single nuclear recoil event candidates were observed during the run. The candidate events exhibit timing characteristics that are not consistent with the hypothesis of a uniform time distribution, and no evidence for a dark matter signal is claimed. These data provide the most sensitive direct detection constraints on WIMP-proton spin-dependent scattering to date, with significant sensitivity at low WIMP masses for spin-independent WIMP-nucleon scattering.

Spin echo small angle neutron scattering using a continuously pumped (3)He neutron polarisation analyser.

We present a new instrument for spin echo small angle neutron scattering (SESANS) developed at the Low Energy Neutron Source at Indiana University. A description of the various instrument components is given along with the performance of these components. At the heart of the instrument are a series of resistive coils to encode the neutron trajectory into the neutron polarisation. These are shown to work well over a broad range of neutron wavelengths. Neutron polarisation analysis is accomplished using a continuously operating neutron spin filter polarised by Rb spin-exchange optical pumping of (3)He. We describe the performance of the analyser along with a study of the (3)He polarisation stability and its implications for SESANS measurements. Scattering from silica Stöber particles is investigated and agrees with samples run on similar instruments.

Defining combat helmet coverage for protection against explosively propelled fragments.

INTRODUCTION: Prevention against head wounds from explosively propelled fragments is currently the Mark 7 general service combat helmet, although only limited evidence exists to define the coverage required for the helmet to adequately protect against such a threat. The Royal Centre for Defence Medicine was tasked by Defence Equipment and Support to provide a framework for determining the optimum coverage of future combat helmets in order to inform the VIRTUS procurement programme. METHOD: A systematic review of the literature was undertaken to identify potential solutions to three components felt necessary to define the ideal helmet coverage required for protection against explosively propelled fragments. RESULTS: The brain and brainstem were identified as the structures requiring coverage by a helmet. No papers were identified that directly defined the margins of these structures to anatomical landmarks, nor how these could be related to helmet coverage. CONCLUSIONS: We recommend relating the margins of the brain to three identifiable anatomical landmarks (nasion, external auditory meatus and superior nuchal line), which can in turn be related to the coverage provided by the helmet. Early assessments using an anatomical mannequin indicate that the current helmet covers the majority of the brain and brainstem from projectiles with a horizontal trajectory but not from ones that originate from the ground. Protection from projectiles with ground-originating trajectories is reduced by helmets with increased stand-off from the skin. Future helmet coverage assessments should use a finite element numerical modelling approach with representative material properties assigned to intracranial anatomical structures to enable differences in projectile trajectory and helmet coverage to be objectively compared.

Superconducting magnetic Wollaston prism for neutron spin encoding.

A magnetic Wollaston prism can spatially split a polarized neutron beam into two beams with different neutron spin states, in a manner analogous to an optical Wollaston prism. Such a Wollaston prism can be used to encode the trajectory of neutrons into the Larmor phase associated with their spin degree of freedom. This encoding can be used for neutron phase-contrast radiography and in spin echo scattering angle measurement (SESAME). In this paper, we show that magnetic Wollaston prisms with highly uniform magnetic fields and low Larmor phase aberration can be constructed to preserve neutron polarization using high temperature superconducting (HTS) materials. The Meissner effect of HTS films is used to confine magnetic fields produced electromagnetically by current-carrying HTS tape wound on suitably shaped soft iron pole pieces. The device is cooled to ~30 K by a closed cycle refrigerator, eliminating the need to replenish liquid cryogens and greatly simplifying operation and maintenance. A HTS film ensures that the magnetic field transition within the prism is sharp, well-defined, and planar due to the Meissner effect. The spin transport efficiency across the device was measured to be ~98.5% independent of neutron wavelength and energizing current. The position-dependent Larmor phase of neutron spins was measured at the NIST Center for Neutron Research facility and found to agree well with detailed simulations. The phase varies linearly with horizontal position, as required, and the neutron beam shows little depolarization. Consequently, the device has advantages over existing devices with similar functionality and provides the capability for a large neutron beam (20 mm × 30 mm) and an increase in length scales accessible to SESAME to beyond 10 µm. With further improvements of the external coupling guide field in the prototype device, a larger neutron beam could be employed.

Brachial plexopathy: a review of traumatic and nontraumatic causes.

OBJECTIVE: This article reviews brachial plexus anatomy in the context of key landmarks, illustrates common findings of traumatic and nontraumatic causes of brachial plexopathies, describes symptoms associated with these maladies, and explains how proper diagnosis impacts clinical decisions. CONCLUSION: Knowledge of brachial plexus anatomy and of the imaging sequelae of traumatic and nontraumatic plexopathies enables the radiologist to more easily identify these afflictions, thereby facilitating a multidisciplinary treatment plan and improving patient outcome.

Anterior chamber gas bubbles in open globe injury.

We present a case of a 40-year-old soldier who was in close proximity to the detonation of an improvised explosive device (IED). Bubbles of gas were visible within the anterior chamber of his left eye. The authors propose that intraocular gas, present acutely after trauma, is diagnostic of open globe injury and is of particular importance in remote military environments.