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Magnetars are young, highly magnetized neutron stars that produce extremely rare giant flares of gamma-rays, the most luminous astrophysical phenomena in our Galaxy. The detection of these flares from outside the Local Group of galaxies has been predicted, with just two candidates so far. Here we report on the extremely bright gamma-ray flare GRB 200415A of April 15, 2020, which we localize, using the Interplanetary Network, to a tiny (20 sq. arcmin) area on the celestial sphere, that overlaps the central region of the Sculptor galaxy at 3.5 Mpc from the Milky Way. From the Konus-Wind detections, we find a striking similarity between GRB 200415A and GRB 051103, the even more energetic flare that presumably originated from the M81/M82 group of galaxies at nearly the same distance (3.6 Mpc). Both bursts display a sharp, millisecond-scale, hard-spectrum initial pulse, followed by an approximately 0.2 s long steadily fading and softening tail. Apart from the huge initial pulses of magnetar giant flares, no astrophysical signal with this combination of temporal and spectral properties and implied energy has been reported previously. At the inferred distances, the energy released in both flares is on par with that of the December 27, 2004 superflare from the Galactic magnetar SGR 1806-20, but with a higher peak luminosity. Taken all together, this makes GRB 200415A and its twin GRB 051103 the most significant candidates for extragalactic magnetar giant flares, both a factor of five more luminous than the brightest Galactic magnetar flare observed previously, thus providing an important step towards a better understanding of this fascinating phenomenon., Preprint version of Nature paper

Neurologic complications of Hodgkin's disease (HD) include both metastatic and non-metastatic involvement of the nervous system. There are at least five paraneoplastic syndromes associated with HD but chorea has not been described. We report the first choreiform disorder as a paraneoplastic complication of HD and only the second case of paraneoplastic chorea in the literature.

The Transient Gamma-Ray Spectrometer (TGRS) was launched aboard the GGS/WIND spacecraft on November 1, 1994. After several deep space orbits (∼2 yrs) WIND will eventually be injected into a halo orbit around the Sun-EarthL1 point. TGRS consists of a 215 cm3 high purityn-type Ge crystal which is kept at cryogenic temperatures by a passive radiative cooler. The energy range covered by the instrument is ∼25–8000 keV with an energy resolution of ∼2–3 keV. The primary task of TGRS is to perform high resolution spectroscopy of gamma-ray bursts and solar flares. Additional objectives are the study of transient x-ray pulsars and, using an on-board passive occulter, the long-term monitoring of sources such as the Crab and the Galactic Center. Since launch, TGRS has been performing exceedingly well, and all the important experiment parameters such as background levels, gain, and resolution have proven to be very stable. To date, TGRS has detected 27 GRBs and three solar flares. Preliminary analysis of our data also indicates that TGRS is indeed sensitive to sources such as the Crab and the Galactic Center.

Very Large Array (VLA) radio observations of precisely-located GRB error boxes have been performed to search for fading and quiescent emission associated with γ-ray bursts. These observations were made as quickly as 23 hours and as late as 13 years after the time of the burst. Our measurements presented here have found GRB error boxes to be empty of sources to the 80 µJy level (λ = 3.6 cm) at 9 months, to 1 mJy (20 cm) at 9 days, and probably to 5 mJy (20 cm) at 23 hours after the bursts.

No absorption lines between 15 and 100 keV have been detected in burst spectra accumulated by BATSE. Almost 250 bursts have been inspected visually, and a computerized search has begun. Our simulations show that BATSE could indeed detect lines similar to those observed byGinga in strong bursts, and our tests of the detectors' actual capabilities demonstrate they function as understood. The apparent discrepancy between BATSE andGinga is not yet compelling, and therefore the BATSE nondetections do not invalidate theGinga detections. Nonetheless, the absence of BATSE line detections indicates a low line-occurrence frequency.

The Transient Gamma Ray Spectrometer (TGRS) is a 215 cm3 passivelycooled germanium detector designed primarily to study spectral features of gamma ray bursts. Since shortly after its launch on 1994 Nov. 1 it has been producing high-resolution spectra of GRBs and solar flares. Some of these spectra are presented here.

We evaluated the significance of the line candidates identified by the visual search of burst spectra from BATSE's spectroscopy detectors. None of the candidates satisfy the detection criteria: anF-test probability less than 10−4 for a feature in one detector and consistency among the detectors which viewed the burst. Most of the candidates are not very significant, and are likely to be fluctuations. Because of the expectation of finding absorption lines, the search was biased towards absorption features. We do not have a quantitative measure of the completeness of the search which would form the basis of a comparison with previous missions. Therefore a more objective computerized search has begun.

The Cambridge Low Frequency Synthesis Telescope (CLFST) is being used to search for prompt radio emission from GRBs at 151 MHz. For this search a special observing mode has recently been developed; the antennas of the CLFST are split into seven groups which are spaced about 30° apart. When triggered by the real-time signals from the BACODINE system the antennas are slewed to the GRB position, with data being sampled at 1.5 or 3-s intervals. The antennas slew at about 10° per minute, so that an appreciable fraction of the sky can be accessed on timescales of a few minutes - any prompt radio emission from a GRB might be delayed by this timescale due to propagation effects.

Malaysia is a complex social and political phenomenon that could easily have become mired in ethnic conflict and economic stagnation. Malaysia has had to manage a shift from a natural resource-based economy to an export-oriented manufacturing system while balancing delicate racial and religious divisions in a democratic, constitutional federation. A proud and nationalist history has been confronted by global economic interdependence. Malaysia’s political leadership has been able to balance competing and almost contradictory domestic and international demands to carve out a prominent position for the country in world affairs while bringing forth a progressive economic entity. That success is neither accidental nor incidental.

Soft gamma repeaters are high-energy transient sources associated with neutron stars in young supernova remnants. They emit sporadic, short (~ 0.1 s) bursts with soft energy spectra during periods of intense activity. The event of March 5, 1979 was the most intense and the only clearly periodic one to date. Here we report on an even more intense burst on August 27, 1998, from a different soft gamma repeater, which displayed a hard energy spectrum at its peak, and was followed by a ~300 s long tail with a soft energy spectrum and a dramatic 5.16 s period. Its peak and time integrated energy fluxes at Earth are the largest yet observed from any cosmic source. This event was probably initiated by a massive disruption of the neutron star crust, followed by an outflow of energetic particles rotating with the period of the star. Comparison of these two bursts supports the idea that magnetic energy plays an important role, and that such giant flares, while rare, are not unique, and may occur at any time in the neutron star's activity cycle., Accepted for publication in Nature

BackgroundDeer mice (Peromyscus maniculatus) are among the most common mammals in North America and are important reservoirs of several human pathogens, including Sin Nombre hantavirus (SNV). SNV can establish a life-long apathogenic infection in deer mice, which can shed virus in excrement for transmission to humans. Patients that die from hantavirus cardiopulmonary syndrome (HCPS) have been found to express several proinflammatory cytokines, including lymphotoxin (LT), in the lungs. It is thought that these cytokines contribute to the pathogenesis of HCPS. LT is not expressed by virus-specific CD4+T cells from infected deer mice, suggesting a limited role for this pathway in reservoir responses to hantaviruses.ResultsWe have cloned the genes encoding deer mouse LTα and LTβ and have found them to be highly similar to orthologous rodent sequences but with some differences in promoters elements. The phylogenetic analyses performed on the LTα, LTβ, and combined data sets yielded a strongly-supported sister-group relationship between the two murines (the house mouse and the rat). The deer mouse, a sigmodontine, appeared as the sister group to the murine clade in all of the analyses. High bootstrap values characterized the grouping of murids.ConclusionNo conspicuous differences compared to other species are present in the predicted amino acid sequences of LTα or LTβ; however, some promoter differences were noted in LTβ. Although more extensive taxonomic sampling is required to confirm the results of our analyses, the preliminary findings indicate that both genes (analyzed both separately and in combination) hold potential for resolving relationships among rodents and other mammals at the subfamily level.

ANGEL et al.1 recently showed how an artificial neural network could be used to measure optical phase distortion induced by atmospheric turbulence, and demonstrated by numerical simulation that such a system could be used to control the six 1.8-m mirrors of the Multiple Mirror Telescope by constantly adjusting them to compensate for atmospheric distortion of the image. The neural network estimates the phase distortion using two images of a reference star, or of a laser-produced guide star2, one image being at the best focus of the telescope while the other is intentionally out of focus. Here we report the successful test of a neural network with a real star. We applied a neural network to in- and out-of-focus images of Vega obtained with the 1.5-m single-mirror telescope at the Starfire Optical Range of the Air Force Phillips Laboratory near Albuquerque, New Mexico. The experimental results agree well with phase reconstructions obtained simultaneously with a conventional wave-front sensor.

The Burst and All Sky Imaging Survey (BASIS) is a proposed mission to provide ∼3 arc second locations of approximately 90 Gamma-Ray Bursts (GRBs) per year. The BASIS coded aperture imaging system requires a segmented detector plane able to detect the interaction position of (10 - 150 keV) photons to less than 100 μm. To develop prototype detector arrays with such fine position resolution we have fabricated many 15 mm × 15 mm × 2 mm 100 μm pitch CdZnTe strip detectors. We have assembled these fine pitch CdZnTe strip detectors into prototype 2 × 2 and 6 × 6 element arrays read out by ASIC electronics. The assembly and electronics readout of the 6 × 6 flight prototype array will be discussed, and preliminary data illustrating the uniformity and efficiency of the array will be presented.

A CdZnTe strip detector large area array (∼ 60 cm2 with 36 detectors) with capabilities for high resolution imaging and spectroscopy has been built as a prototype for a space flight gamma ray burst instrument. The detector array also has applications in nuclear medical imaging. Two dimensional orthogonal strip detectors with 100 gm pitch have been fabricated and tested. Details for the array design, fabrication and evaluation of the detectors will be presented.

Gamma-ray Bursts (GRBs) are bright flashes of high energy photons that can last from about 10 milliseconds to 10 minutes. Their origin and nature have puzzled the scientific community for about 25 years until 1997, when the first X-ray afterglows of long (> 2 s duration) bursts were detected and the first optical and radio counterparts were found. These measurements established that long GRBs are typically at high redshift (z 1.6) and are in sub-luminous star-forming host galaxies. They are likely produced in core-collapse explosions of a class of massive stars that give rise to highly relativistic jets (collapsar model). Internal inhomogeneities in the velocity field of the relativistic expanding flow lead to collisions between fast moving and slow moving fluid shells and to the formation of internal shock waves. These shocks are believed to produce the observed prompt emission in the form of irregularly shaped and spaced pulses of gamma-rays, each pulse corresponding to a distinct internal collision. The expansion of the jet outward into the circumstellar medium is believed to give rise to ``external'' shocks, responsible for producing the smoothly fading afterglow emission seen in the X-ray, optical and radio bands. Here we report on the gamma-ray and x-ray observation of the most distant gamma-ray burst ever observed: its redshift of 6.29 translates to a distance of 13 billion light-years from Earth, corresponding to a time when the Universe was just 700 million to 750 million years old. The discovery of a gamma-ray burst at such a large redshift implies the presence of massive stars only 700 million years after the Big Bang. The very high redshift bursts represent a good way to study the re-ionization era soon after the Universe came out of the Dark Ages.

Contact between surfaces usually occurs at asperities under compression or at connecting ligaments, depending on how the interface is formed. This paper deals with the nondestructive evaluation of the topology of contact and with the use of this information to predict the effects that loads borne by these contacts have on mechanical properties. Two specific examples are discussed: a fatigue crack and a diffusion bond. Asperity contact along the fracture surface of a fatigue crack partially shields the crack tip from the externally applied driving force. Using information from acoustic experiments, the geometry of the asperities, the contacting stress, and the shielding stress intensity factor have been estimated. Acoustically, a diffusion bonded interface looks very similar to that joining the two sides of a partially closed crack. In this particular case, the acoustically determined geometry of well-bonded ligaments can be verified by fractography of destructively tested samples whose bond strength has also been determined. Models to determine the bond strength from the ligament geometry are being suggested.

William Hunter (1718-1783), the elder of the two famous Hunter brothers, is best known for his remarkable book The Anatomy to the Human Gravid Uterus, and for his contributions to the art of midwifery. However, Hunter also made significant observations in cardiovascular disease, in comparative anatomy, and paleopathology. It is perhaps not sufficiently known that he also made significant contributions in rheumatic disease, and in particular, the anatomy and physiology of cartilage.

There is an increasing tendency for modern electrolytic zinc plants to experience water balance and magnesium control problems because of the simultaneous need to maximize zinc recovery and produce environmentally acceptable leach residues and precipitates. The Selective Zinc Precipitation process developed by the Electrolytic Zinc Company of Australasia involves the precipitation of basic zinc sulfate using limestone. Water balance and magnesium control may be achieved by either discarding the process filtrate, or by using it to wash precipitates in a closed circuit operation. The process filter cake is used as a neutralizing agent in the zinc plant. The process can be operated over a wide range of temperatures and calcined zinc concentrate may be preferred to limestone as a zinc precipitant to minimize the discard of sulfate. This paper is particularly concerned with a quantitative assessment of various modes of integrating the process into modern electrolytic zinc plants.

It has been shown that the acoustic response of imperfect interfaces may be described by a quasi-static spring model. In the present paper, experimental data on the geometry of the contacts between two diffusion-bonded blocks have been used to determine the “spring stiffness” of such interfaces which have been correlated with experimentally determined ultrasonic reflection coefficients. The correlation between the theoretical reflection coefficient and the “spring stiffness” was found to be in excellent agreement with experimentally-observed values, if the disbonds are of infinitesimally small thickness. For disbonds of finite thickness, the agreement is less satisfactory. Reasons for the discrepancy in the latter case are unknown at the present time.

Experimental data are presented for comparison of the determination of oxygen by the16O(3He, p)18F,16O(3He, α)15O and18O(p, α)15N prompt nuclear reactions, and of their use in the lattice location, by the ion-channelling technique, of oxygen atoms in single crystal targets of elements such as niobium, where oxygen contents of ≈0.1 atomic % or more can be obtained. Both reaction cross-sections and lattice-defect production rates are considered in the comparison. Details are given of an arrangement for automatic crystallographic angular scanning of nuclear reaction and backscattering yields in channelling/lattice location measurements.

The application of ultrasonic reflectivity for the characterization of a variety of copper diffusion bonds is described. The quality of each diffusion bond has been described by its ultimate tensile strength. Furthermore, fractography of the failed bonds provided information on the relative fraction of bonded areas as well as the geometry of the bonds. This paper provides the experimental results obtained as well as empirical correlations between the quantities determined.

(AxT6)F1 hybrid mice received s.c. transplants from (AxT6)F1 mammary carcinomas. At 1, 2 or 4 weeks after tumour transplantation, the mice were bled to obtain plasma and then challenged with 25 micron E. coli lipopolysaccharide (LPS) endotoxin i.v. The mice were killed 24 hr later, further plasma was obtained and their liver ratios and spleen ratios were determined. A similar procedure was carried out on non-tumour-bearing mice. Progressive tumour growth was associated with an increase in the liver ratio. In parallel, mice with 4-week tumour transplant showed increased uptake of colloidal carbon particles and 51Cr-labelled sheep red blood cells in the liver. The plasma amino aspartate transaminase (AST) and the ornithine carbamoyl transferase (OCT) showed a constant rise in all groups of mice after LPS injection. However, at 24 hr after LPS injection, the AST level showed the greatest rise in mice with 4-week tumour transplants. By contrast, OCT, which is liberated only from hepatocytes, showed the greatest rise in non-tumour-bearing mice. Images Fig. 2 Fig. 3

Using only the analyticity of the γγπ0 form factor and the experimental lifetime of the π0, we determine the bound $$\int\limits_{4m_\pi ^2 }^\infty {ds s^k \sigma _{tot} (s) \geqslant 35.3 \mu b (MeV)^2 (4m_\pi )^{2k} \{ 5.91 + k^2 + 4.44k + 256a^2 - 32ak - 70.9a\} } $$ (1) where σtot(s) is the total cross-section for e+e−→π0γ,k is an arbitrary real number, anda is the slope of the form factor ats=0. Bounds are also obtained for the isoscalar and isovector cross-sections separately.

A new method of hand-grip assessment has been applied to the problem of quantitative evaluation of morning stiffness. Treatment with indomethacin (known to reduce morning stiffness in rheumatoid patients) was shown to cause significant improvement in grip parameters, particularly in the power output achieved during grip development.

ELECTROSTATIC precipitators are widely used to remove dust particles from gases and the mechanism of this is well understood. One major application is in the cleaning of a sulphur dioxide produced in smelting of metalliferous sulphide ores before its conversion to sulphuric acid and the precipitated material is often found to contain mercury. We have shown that the concentration of mercury is below the saturation level and therefore present as atoms so the accepted mechanism for solid particle collection is not involved in mercury removal. We have investigated the phenomenon in the laboratory using air as the carrier gas at room temperature, and by large scale tests carried out in an 800 tonne d−1 sulphuric acid plant treating the gases formed by roasting zinc sulphide concentrate. In both types of test a discharge wire and earthed collector tube precipitator configuration was used. In the plant tests the roaster gas contained 9% sulphur dioxide and was saturated with water. In both the laboratory and plant tests the gas streams were unsaturated with respect to elemental mercury vapour.

IN a recent communication1 Gulbransen showed that reactions between graphite and hydrogen which are thermo-chemically unfavourable can proceed to a measurable extent under conditions where the reaction products are rapidly removed or the system quenched. In view of this it is considered of interest to report certain observations made in these laboratories during experiments in which graphite was mechanically ground in the presence of hydrogen, and also of nitrogen. It was found that both these gases are taken up by graphite if present in the grinding chamber during the comminution process. The grinding was carried out using a vibratory ball mill fitted with gas-tight grinding chambers to which the gas was metered during grinding to maintain the pressure constant at 1 atm. The graphite was synthetic and contained less than 0.02 per cent of ash by weight, while the gases were of commercial quality at 99.9 per cent purity. The grinding medium was 0.25 in. steel balls. We concluded that the absorption of the gases must be due to some form of chemical reaction with the graphite for the following reasons. First, direct adsorption of the gases by the fresh graphite surface produced cannot wholly account for the uptake, because the extent of uptake is greater than when the graphite is first ground in vacuo and then placed in contact with the gas, even though the amount of fresh surface produced is greater in the latter case. Second, it is reasoned that neither hydrogen nor nitrogen reacts with the active (free radical) sites produced by fracture of the graphite planes, because we have shown that these are most readily neutralized by subsequent treatment with oxygen and that the amount of oxygen absorbed depends only on the fresh surface produced, irrespective of whether the graphite is initially ground in hydrogen, nitrogen or in vacuo. Finally, we have observed that graphite ground in the presence of nitrogen has a strong smell resembling that of hydrogen cyanide, whereas no such smell is detectable if the grinding is carried out in vacuo.

THE behaviour of Hurst's1 range R is incompletely known, but it is evidently closely related to the standard deviation of the sum of N successive quantities, since the sums used in finding R are highly correlated. In fact, for a large number N of independent quantities, of standard deviation σ, R∝σ√N. If the quantities are correlated: where σ2 u(N) is the variance of mean of N successive quantities. If N is large the effect of differences between deviations from the measured mean and deviations from the true mean becomes small.