Constraints on Minute-Scale Transient Astrophysical Neutrino Sources

High-energy neutrino emission has been predicted for several short-lived astrophysical transients including gamma-ray bursts (GRBs), core-collapse supernovae with choked jets, and neutron star mergers. IceCube's optical and x-ray follow-up program searches for such transient sources by looking for two or more muon neutrino candidates in directional coincidence and arriving within 100 s. The measured rate of neutrino alerts is consistent with the expected rate of chance coincidences of atmospheric background events and no likely electromagnetic counterparts have been identified in Swift follow-up observations. Here, we calculate generic bounds on the neutrino flux of short-lived transient sources. Assuming an E^{-2.5} neutrino spectrum, we find that the neutrino flux of rare sources, like long gamma-ray bursts, is constrained to <5% of the detected astrophysical flux and the energy released in neutrinos (100 GeV to 10 PeV) by a median bright GRB-like source is <10^{52.5}  erg. For a harder E^{-2.13} neutrino spectrum up to 30% of the flux could be produced by GRBs and the allowed median source energy is <10^{52}  erg. A hypothetical population of transient sources has to be more common than 10^{-5}  Mpc^{-3}  yr^{-1} (5×10^{-8}  Mpc^{-3}  yr^{-1} for the E^{-2.13} spectrum) to account for the complete astrophysical neutrino flux.

Cryo-EM Structure (4.5-Å) of Yeast Kinesin-5-Microtubule Complex Reveals a Distinct Binding Footprint and Mechanism of Drug Resistance

Kinesin-5s are microtubule-dependent motors that drive spindle pole separation during mitosis. We used cryo-electron microscopy to determine the 4.5-Å resolution structure of the motor domain of the fission yeast kinesin-5 Cut7 bound to fission yeast microtubules and explored the topology of the motor–microtubule interface and the susceptibility of the complex to drug binding. Despite their non-canonical architecture and mechanochemistry, Schizosaccharomyces pombe microtubules were stabilized by epothilone at the taxane binding pocket. The overall Cut7 footprint on the S. pombe microtubule surface is altered compared to mammalian tubulin microtubules because of their different polymer architectures. However, the core motor–microtubule interaction is tightly conserved, reflected in similar Cut7 ATPase activities on each microtubule type. AMPPNP-bound Cut7 adopts a kinesin-conserved ATP-like conformation including cover neck bundle formation. However, the Cut7 ATPase is not blocked by a mammalian-specific kinesin-5 inhibitor, consistent with the non-conserved sequence and structure of its loop5 insertion.

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Epothilone binds at the taxane binding site to stabilize S. pombe microtubules.

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S. pombe Cut7 has a distinct binding footprint on S. pombe microtubules.

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The core interface driving microtubule activation of motor ATPase is conserved.

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Loop5 of Cut7 adopts a distinctive conformation rendering Cut7 ATPase insensitive to STLC inhibition.

Search for neutrinos from decaying dark matter with IceCube: IceCube Collaboration

With the observation of high-energy astrophysical neutrinos by the IceCube Neutrino Observatory, interest has risen in models of PeV-mass decaying dark matter particles to explain the observed flux. We present two dedicated experimental analyses to test this hypothesis. One analysis uses 6 years of IceCube data focusing on muon neutrino 'track' events from the Northern Hemisphere, while the second analysis uses 2 years of 'cascade' events from the full sky. Known background components and the hypothetical flux from unstable dark matter are fitted to the experimental data. Since no significant excess is observed in either analysis, lower limits on the lifetime of dark matter particles are derived: we obtain the strongest constraint to date, excluding lifetimes shorter than10 28 s at 90% CL for dark matter masses above 10 TeV .

Fine- and coarse-scale movements and habitat use by Wood Turtles (Glyptemys insculpta) based on probabilistic modeling of radiotelemetry and GPS-telemetry data

Understanding animal movement and habitat use is critical for the delineation of habitat requiring protection for species at risk. Defining critical habitat requires studies with observations at a fine enough scale to reflect how animals use and move among habitats and include enough individuals to generalize findings to the population. We present results of a multiyear study on 48 adult Wood Turtles (Glyptemys insculpta (Le Conte, 1830)) from two different populations monitored with low-frequency radiotelemetry and high-frequency GPS telemetry. Results demonstrated the propensity for conventional radiotelemetry to underestimate cumulative distances moved and overestimate the amount of habitat used by Wood Turtles. Together the two data sets demonstrate the propensity for Wood Turtles to remain in close proximity to the river and that some differences in habitat use occur between the sexes; males tended to move parallel to the river, whereas females moved perpendicular to the river. The GPS-telemetry data provided a robust spatiotemporal data set that provided a better understanding of frequently used habitat types and features. Overall, study results suggest that currently delineated areas of protected habitat are likely to be effective in conserving these two populations and provides significantly improved, spatially explicit knowledge that can be used to inform further mitigation efforts if necessary.

Multimessenger observations of a flaring blazar coincident with high-energy neutrino IceCube-170922A

Previous detections of individual astrophysical sources of neutrinos are limited to the Sun and the supernova 1987A, whereas the origins of the diffuse flux of high-energy cosmic neutrinos remain unidentified. On 22 September 2017, we detected a high-energy neutrino, IceCube-170922A, with an energy of ~290 tera–electron volts. Its arrival direction was consistent with the location of a known γ-ray blazar, TXS 0506+056, observed to be in a flaring state. An extensive multiwavelength campaign followed, ranging from radio frequencies to γ-rays. These observations characterize the variability and energetics of the blazar and include the detection of TXS 0506+056 in very-high-energy γ-rays. This observation of a neutrino in spatial coincidence with a γ-ray–emitting blazar during an active phase suggests that blazars may be a source of high-energy neutrinos.

Nucleotide- and Mal3-dependent changes in fission yeast microtubules suggest a structural plasticity view of dynamics

Using cryo-electron microscopy, we characterize the architecture of microtubules assembled from Schizosaccharomyces pombe tubulin, in the presence and absence of their regulatory partner Mal3. Cryo-electron tomography reveals that microtubules assembled from S. pombe tubulin have predominantly B-lattice interprotofilament contacts, with protofilaments skewed around the microtubule axis. Copolymerization with Mal3 favors 13 protofilament microtubules with reduced protofilament skew, indicating that Mal3 adjusts interprotofilament interfaces. A 4.6-Å resolution structure of microtubule-bound Mal3 shows that Mal3 makes a distinctive footprint on the S. pombe microtubule lattice and that unlike mammalian microtubules, S. pombe microtubules do not show the longitudinal lattice compaction associated with EB protein binding and GTP hydrolysis. Our results firmly support a structural plasticity view of microtubule dynamics in which microtubule lattice conformation is sensitive to a variety of effectors and differently so for different tubulins.

Microtubules are vital and highly conserved components of the cytoskeleton. Here the authors carry out a structural analysis of fission yeast microtubules in the presence and absence of the microtubule end-binding protein Mal3 that demonstrates structural plasticity amongst microtubule polymers.

Measurement of the ν μ energy spectrum with IceCube-79: IceCube Collaboration

IceCube is a neutrino observatory deployed in the glacial ice at the geographic South Pole. The ν μ energy unfolding described in this paper is based on data taken with IceCube in its 79-string configuration. A sample of muon neutrino charged-current interactions with a purity of 99.5% was selected by means of a multivariate classification process based on machine learning. The subsequent unfolding was performed using the software Truee. The resulting spectrum covers an E ν -range of more than four orders of magnitude from 125 GeV to 3.2 PeV. Compared to the Honda atmospheric neutrino flux model, the energy spectrum shows an excess of more than 1.9 σ in four adjacent bins for neutrino energies E ν ≥ 177.8 TeV . The obtained spectrum is fully compatible with previous measurements of the atmospheric neutrino flux and recent IceCube measurements of a flux of high-energy astrophysical neutrinos.

Constraints on Ultrahigh-Energy Cosmic-Ray Sources from a Search for Neutrinos above 10 PeV with IceCube

We report constraints on the sources of ultrahigh-energy cosmic rays (UHECRs) above 10^{9}  GeV, based on an analysis of seven years of IceCube data. This analysis efficiently selects very high- energy neutrino-induced events which have deposited energies from 5×10^{5}  GeV to above 10^{11}  GeV. Two neutrino-induced events with an estimated deposited energy of (2.6±0.3)×10^{6}  GeV, the highest neutrino energy observed so far, and (7.7±2.0)×10^{5}  GeV were detected. The atmospheric background-only hypothesis of detecting these events is rejected at 3.6σ. The hypothesis that the observed events are of cosmogenic origin is also rejected at >99% CL because of the limited deposited energy and the nonobservation of events at higher energy, while their observation is consistent with an astrophysical origin. Our limits on cosmogenic neutrino fluxes disfavor the UHECR sources having a cosmological evolution stronger than the star formation rate, e.g., active galactic nuclei and γ-ray bursts, assuming proton-dominated UHECRs. Constraints on UHECR sources including mixed and heavy UHECR compositions are obtained for models of neutrino production within UHECR sources. Our limit disfavors a significant part of parameter space for active galactic nuclei and new-born pulsar models. These limits on the ultrahigh-energy neutrino flux models are the most stringent to date.

Layers of Diagnosis for Planned Relational Change in Organizations

Planned change innately involves shifting relationships and patterns of interaction. Social network analysis can make these patterns visible and so help target interventions. Yeta great deal of conscious and unconscious interpersonal dynamics that should also be considered exist beneath the surface of such patterns. This in-depth case study illustrates how clinical and network approaches to diagnosis can reveal different change interventions. Three principles for combining clinical and social network techniques are identified. First, in addition to viewing structure as constraining action, networks should be considered as symptoms of deeper organizational issues. Second, networks should be understood normatively in terms of rational task requirements but also in terms of other, less observable (and possibly irrational) needs of organization members. Finally, analysts and change agents are best served by developing relationships of trust when applying social network analysis and interpreting patterns in ways meaningful to those being assessed.

Observer effects occur when estimating alert but not flight-initiation distances

Context The estimation of alert (vigilance) and flight-initiation (escape) distances (AD and FID, respectively) has underpinned theoretical and applied studies of the escape behaviour and management of disturbance to wildlife. Many studies use multiple observers, and some conduct meta-analyses; these efforts assume no observer effects in the estimation of these distances. Aims and methods We compared the estimates of FID and AD under ideal conditions (i.e. of black swans, Cygnus atratus, a large species with obvious behaviour, and at a location where swans allowed close approaches in open habitats), by one experienced and four inexperienced observers. Key results FID did not differ among observers but AD differed between the experienced and all inexperienced observers, and among inexperienced observers. Thus, FID estimates appear more repeatable than those of AD. Experience apparently results in more conservative estimates of AD. Conclusions FID represents a repeatable measure that is consistent across observers. This study supports its broad application in the study of wildlife escape behaviour. Implications We recommend the use of FID rather than AD for comparative analyses that involve multiple observers, because FID is more reliably measured.

Treatment of patients with intermediate cardiovascular risk: Are clinical measures enough?

AIM

Clinical measures of cardiovascular disease risk (CVD) are important tools for establishing therapy to lower CVD risk. Risk assessment has come under criticism because clinical measures can underestimate or overestimate CVD risk. We assessed CVD risk in 252 subjects without evidence of CVD to establish therapy of one or more risk factors from clinical indications. The subjects all had intermediate CVD risk using the Framingham score.

RESULTS

Average age was 59.1 years. 23.8% were smokers, 59.1% were hypertensive, 65.1% had hyperlipidemia. BMI was greater than 30 kg/M(2) in 56% and diabetes was present in 43.7%. In this cohort, 86.9% required therapy for hypertension or hyperlipidemia, and this proportion increased to 95.6% when subjects with diabetes were included. Of the remaining 4.4% (11 subjects), 7 reached intermediate risk based on cigarette smoking and 4 based on age >65 years old. Among diabetics, 94/110 had another risk factor and would require statin and ACE or ARB therapy.

CONCLUSIONS

Of subjects at intermediate risk for CVD, 98.4% would not require further testing to decide on therapy to lower CVD risk. Although 16 diabetic subjects had no other risk factors, current guidelines suggest that these subjects should be treated to reduce CVD risk.

Reducing cardiovascular disease risk in medically underserved urban and rural communities

OBJECTIVES

The aim of this study is to evaluate methods for lowering cardiovascular disease (CVD) risk in asymptomatic urban and rural underserved subjects.

BACKGROUND

Medically underserved populations are at increased CVD risk, and systems to lower CVD risk are needed. Nurse management (NM) and telemedicine (T) systems may provide low-cost solutions for this care.

METHODS

We randomized 465 subjects without overt CVD, with Framingham CVD risk >10% to NM with 4 visits over 1 year, or NM plus T to facilitate weight, blood pressure (BP), and physical activity reporting. The study goal was to reduce CVD risk by 5%.

RESULTS

Three hundred eighty-eight subjects completed the study. Cardiovascular disease risk fell by ≥ 5% in 32% of the NM group and 26% of the T group (P, nonsignificant). In hyperlipidemic subjects, total cholesterol decreased (NM -21.9 ± 39.4, T -22.7 ± 41.3 mg/dL) significantly. In subjects with grade II hypertension (systolic BP ≥ 160 mm Hg, 24% of subjects), both NM and T groups had a similar BP response (average study BP: NM 147.4 ± 17.5, T 145.3. ± 18.4, P is nonsignificant), and for those with grade I hypertension (37% of subjects), T had a lower average study BP compared to NM (NM 140.4 ± 16.9, T 134.6 ± 15.0, P = .058). In subjects at high risk (Framingham score ≥ 20%), risk fell 6.0% ± 9.9%; in subjects at intermediate risk (Framingham score ≥ 10, < 20), risk fell 1.3% ± 4.5% (P < .001 compared to high-risk subjects). Medication adherence was similar in both high- and intermediate-risk subjects.

CONCLUSIONS

In 2 underserved populations, CVD risk was reduced by a nurse intervention; T did not add to the risk improvement. Reductions in BP and blood lipids occurred in both high- and intermediate-risk subjects with greatest reductions noted in the high-risk subjects. Frequent communication using a nurse intervention contributes to improved CVD risk in asymptomatic, underserved subjects with increased CVD risk. Telemedicine did not change the effectiveness of the nurse intervention.

Enhanced Liver Fibrosis (ELF) test accurately identifies liver fibrosis in patients with chronic hepatitis C

Assessment of liver fibrosis is important in determining prognosis and evaluating interventions. Due to limitations of accuracy and patient hazard of liver biopsy, non-invasive methods have been sought to provide information on liver fibrosis, including the European liver fibrosis (ELF) test, shown to have good diagnostic accuracy for the detection of moderate and severe fibrosis. Access to independent cohorts of patients has provided an opportunity to explore if this test could be simplified. This paper reports the simplification of the ELF test and its ability to identity severity of liver fibrosis in external validation studies in patients with chronic hepatitis C (CHC). Paired biopsy and serum samples from 347 naïve patients with CHC in three independent cohorts were analysed. Diagnostic performance characteristics were derived (AUROC, sensitivity and specificity, predictive values), and clinical utility modelling performed to determine the proportion of biopsies that could have been avoided if ELF test was used in this patient group. It was possible to simplify the original ELF test without loss of performance and the new algorithm is reported. The simplified ELF test was able to predict severe fibrosis [pooled AUROC of 0.85 (95% CI 0.81-0.89)] and using clinical utility modelling to predict severe fibrosis (Ishak stages 4-6; METAVIR stages 3 and 4) 81% of biopsies could have been avoided (65% correctly). Issues of spectrum effect in diagnostic test evaluations are discussed. In chronic hepatitis C a simplified ELF test can detect severe liver fibrosis with good accuracy.

A metallization and bonding approach for high performance carbon nanotube thermal interface materials

A method has been developed to create vertically aligned carbon nanotube (VACNT) thermal interface materials that can be attached to a variety of metallized surfaces. VACNT films were grown on Si substrates using standard CVD processing followed by metallization using Ti/Au. The coated CNTs were then bonded to metallized substrates at 220 °C. By reducing the adhesion of the VACNTs to the growth substrate during synthesis, the CNTs can be completely transferred from the Si growth substrate and used as a die attachment material for electronic components. Thermal resistance measurements using a photoacoustic technique showed thermal resistances as low as 1.7 mm(2) K W(-1) for bonded VACNT films 25-30 µm in length and 10 mm(2) K W(-1) for CNTs up to 130 µm in length. Tensile testing demonstrated a die attachment strength of 40 N cm(-2) at room temperature. Overall, these metallized and bonded VACNT films demonstrate properties which are promising for next-generation thermal interface material applications.

The fabrication of high aspect ratio carbon nanotube arrays by direct laser interference patterning

High aspect ratio periodic carbon nanotube arrays were fabricated using direct laser interference patterning with a frequency tripled Nd:YAG (YAG: yttrium aluminium garnet) laser (lambda = 355 nm) emitting 10 ns laser pulses. The depth of the fabricated arrays could be adjusted by controlling the number of laser pulses. Application of successive laser pulses (10-20) induced pattern distortion, resulting in the formation of conical organized arrays. The number of laser pulses necessary to produce this distortion is proportional to the spatial period of the interference pattern. Raman spectroscopy analyses confirmed that the chemical form of the carbon nanotubes was preserved after patterning.