Efficacy and toxicity of treatment with the anti-CTLA-4 antibody ipilimumab in patients with metastatic melanoma after prior anti-PD-1 therapy

Background:

Recent phase III clinical trials have established the superiority of the anti-PD-1 antibodies pembrolizumab and nivolumab over the anti-CTLA-4 antibody ipilimumab in the first-line treatment of patients with advanced melanoma. Ipilimumab will be considered for second-line treatment after the failure of anti-PD-1 therapy.

Methods:

We retrospectively identified a cohort of 40 patients with metastatic melanoma who received single-agent anti-PD-1 therapy with pembrolizumab or nivolumab and were treated on progression with ipilimumab at a dose of 3 mg kg⁻¹ for a maximum of four doses.

Results:

Ten percent of patients achieved an objective response to ipilimumab, and an additional 8% experienced prolonged (>6 months) stable disease. Thirty-five percent of patients developed grade 3–5 immune-related toxicity associated with ipilimumab therapy. The most common high-grade immune-related toxicity was diarrhoea. Three patients (7%) developed grade 3–5 pneumonitis leading to death in one patient.

Conclusions:

Ipilimumab therapy can induce responses in patients who fail the anti-PD-1 therapy with response rates comparable to previous reports. There appears to be an increased frequency of high-grade immune-related adverse events including pneumonitis that warrants close surveillance.

Assessing the performance of the Birmingham Vasculitis Activity Score at diagnosis for children with antineutrophil cytoplasmic antibody-associated vasculitis in A Registry for Childhood Vasculitis (ARChiVe)

OBJECTIVE

There are no validated tools for measuring disease activity in pediatric vasculitis. The Birmingham Vasculitis Activity Score (BVAS) is a valid disease activity tool in adult vasculitis. Version 3 (BVAS v.3) correlates well with physician's global assessment (PGA), treatment decision, and C-reactive protein in adults. The utility of BVAS v.3 in pediatric vasculitis is not known. We assessed the association of BVAS v.3 scores with PGA, treatment decision, and erythrocyte sedimentation rate (ESR) at diagnosis in pediatric antineutrophil cytoplasmic antibody-associated vasculitis (AAV).

METHODS

Children with AAV diagnosed between 2004 and 2010 at all ARChiVe centers were eligible. BVAS v.3 scores were calculated with a standardized online tool (www.vasculitis.org). Spearman's rank correlation coefficient (r(s)) was used to test the strength of association between BVAS v.3 and PGA, treatment decision, and ESR.

RESULTS

A total of 152 patients were included. The physician diagnosis of these patients was predominantly granulomatosis with polyangiitis (n = 99). The median BVAS v.3 score was 18.0 (range 0-40). The BVAS v.3 correlations were r(s) = 0.379 (95% CI 0.233 to 0.509) with PGA, r(s) = 0.521 (95% CI 0.393 to 0.629) with treatment decision, and r(s) = 0.403 (95% CI 0.253 to 0.533) with ESR.

CONCLUSION

Applied to children with AAV, BVAS v.3 had a weak correlation with PGA and moderate correlation with both ESR and treatment decision. Prospective evaluation of BVAS v.3 and/or pediatric-specific modifications to BVAS v.3 may be required before it can be formalized as a disease activity assessment tool in pediatric AAV.

Long-term response of juvenile idiopathic arthritis after conditioning with 8 Gy total body irradiation followed by autologous peripheral blood stem cells: case report

Investigations of HCT for refractory JIA have employed high dose immunosuppressive drugs, such as CY and ATG with or without low dose TBI. Initial disease response has been observed in approximately two-thirds of patients; however, relapse occurs in about half of the responders. The current report describes a regimen with substantially increased dose of TBI, previously shown to be associated with high rate of disease response in adult patients with refractory MS and severe SSc. We report outcome of the lead patient in this pilot study, who remains in complete remission now, five yr after HCT. This regimen should be considered for patients with JIA refractory to medical therapies, including previous low intensity regimen HCT.

Recognition, diagnosis, and treatment of histoplasmosis complicating tumor necrosis factor blocker therapy

Life-threatening histoplasmosis is one of the most common opportunistic infections in patients receiving tumor necrosis factor (TNF) blockers. Delays in considering the diagnosis may lead to increased morbidity and mortality. Most affected patients present with pneumonitis, usually accompanied by additional signs of progressive dissemination, or with signs of progressive dissemination alone. The diagnosis often can be promptly established using antigen detection or direct examination of bronchoalveolar lavage specimens. If histoplasmosis is diagnosed promptly, antifungal therapy is highly effective. After a favorable clinical response, the safety of both discontinuation of antifungal therapy and the resumption of TNF blocker remains undetermined. The management of the immune reconstitution inflammatory syndrome that may follow discontinuation of TNF blockers also requires investigation. Prescribers should become aware of the recognition, diagnosis, and treatment of histoplasmosis and educate recipients about decreasing their risk of exposure and both recognizing and reporting signs of early infection.

Prevalence of and annual ambulatory health care visits for pediatric arthritis and other rheumatologic conditions in the United States in 2001-2004

OBJECTIVE

To estimate the prevalence of and the annual number of ambulatory health care visits for pediatric arthritis and other rheumatologic conditions.

METHODS

We used physician office visit, outpatient department visit, and emergency department visit data from the 2001-2004 National Ambulatory Medical Care Survey and 2001-2004 National Hospital Ambulatory Medical Care Survey to estimate annual visits for the International Classification of Diseases, Ninth Revision, Clinical Modification codes thought to represent significant pediatric arthritis and other rheumatologic conditions (SPARC). We converted visit estimates into prevalence estimates using data on the number of prior annual visits per patient. Synthetic estimates for states were produced using national rates.

RESULTS

The average annualized estimate of the number of children with SPARC was 294,000 (95% confidence interval [95% CI] 188,000-400,000). The annualized number of ambulatory health care visits for SPARC was 827,000 (95% CI 609,000-1,044,000).

CONCLUSION

Pediatric arthritis estimates have varied widely because it is an umbrella term for which there are many definitions and because it is a relatively uncommon condition from a population surveillance perspective. Our estimates suggest that arthritis-related health care visits impose a substantial burden on the pediatric health care system. One advantage of this surveillance paradigm is that it has established a starting point for tracking the national prevalence of arthritis and rheumatologic conditions in children on an ongoing basis using existing infrastructure rather than expensive new surveys. This surveillance system will help us monitor and predict the health care needs of patients with these conditions.

Macrophage activation syndrome and other systemic inflammatory conditions after BMT

Autologous hematopoietic cell transplantation (HCT) is being used to treat autoimmune diseases refractory to conventional therapy, including rheumatoid arthritis. Macrophage activation syndrome (MAS) is a descriptive term for a systemic inflammatory disorder that has been described in patients with juvenile rheumatoid arthritis (JRA). This case report describes a young adult with systemic JRA (sJRA) who developed MAS on day # 12 post-autologous transplantation. The patient developed high fever, laboratory evidence of disseminated intravascular coagulation (DIC), hepatocellular injury, pancytopenia and hyper-ferritinemia. All viral, bacterial and fungal studies were negative and the patient improved with high-dose glucocorticosteroid and cyclosporine therapy. Extreme elevation of serum ferritin was documented and helpful in monitoring response to therapy. A number of systemic inflammatory syndromes have been described in association with HCT. These include DIC, 'engraftment syndrome,' infection-associated hemophagocytic syndrome and familial hemophagocytic lymphohistiocytosis. Macrophage activation syndrome presents with features of DIC and is closely related or identical to infection-associated hemophagocytic syndrome. The diagnosis needs to be established in a timely fashion because early and appropriate treatment may improve outcome.

A randomized controlled trial of calcium supplementation to increase bone mineral density in children with juvenile rheumatoid arthritis

OBJECTIVE

To examine the effects of daily supplementation with calcium (Ca) in combination with vitamin D on total body and lumbar spine bone mineral density (BMD) in patients with juvenile rheumatoid arthritis (JRA) who had not taken corticosteroids for at least 3 months prior to the beginning of the study.

METHODS

One hundred ninety-eight children and adolescents (141 girls and 57 boys) with JRA, ages 6 to 18 years, with a mean +/- SD age of 11.7 +/- 3.3 years and a mean +/- SD disease duration of 5.6 +/- 3.8 years at the beginning of the study, were enrolled in this randomized double-blind, placebo-controlled trial to receive either daily oral supplements of 1,000 mg of Ca and 400 IU of vitamin D (n = 103) or matched placebo tablets and 400 IU of vitamin D (n = 95) for 24 months. Total body BMD (TBBMD) was measured by dual x-ray absorptiometry at baseline and every 6 months for 24 months.

RESULTS

At baseline, the mean +/- SD TBBMD was 0.89 +/- 0.14 gm/cm2 among patients randomized to the Ca group and 0.87 +/- 0.14 gm/cm2 among those randomized to placebo (P = 0.445). At 24 months, the mean +/- SD TBBMD among those receiving Ca was 0.95 +/- 0.13 gm/cm2, compared with 0.92 +/- 0.14 gm/cm2 among those receiving placebo. A longitudinal random-effects mixed model analysis that controlled for differences in the subject's initial BMD, sex, Tanner stage, adherence to the study medication regimen, and body composition revealed significantly higher TBBMD among patients who received Ca compared with patients who received placebo during the study period (P = 0.03).

CONCLUSION

Ca supplementation resulted in a small, but statistically significant, increase in TBBMD compared with placebo in children with JRA.

Prevalence of elevated antithyroid antibodies and antinuclear antibodies in children with immune thrombocytopenic purpura

The prevalence and significance of autoantibodies found at the time of diagnosis of childhood ITP were studied to correlate their presence with risk for development of chronic ITP. Children presenting with acute or chronic ITP to The James Whitcomb Riley Hospital for Children between July 1993 and September 1994 were tested at study entry and followed for the presence of antithyroid antibodies (ATA), antinuclear antibodies (ANA), Coombs' reactivity, and anti-human immunodeficiency virus (HIV) antibodies. Grouped data were evaluated for significance using Fisher's exact t-test. Thirty-one patients were enrolled in the study with a median age of 8 years (range 17 months-16 years) and male-to-female ratio of 1:1.8. Forty-two percent of these children had an acute course of ITP, and 58% of children had a chronic course of ITP. Of children with acute ITP, three (23%) of the patients had an acute nonplatelet autoantibody detected. Of the children with chronic ITP, six (33%) of the children had at least one abnormal antibody value. Five children (16%) tested positive for ATA: 2 children with acute ITP and 3 with chronic ITP. Five children had positive ANA, and of these children, 4 (80%) had chronic ITP. Sixty-seven percent of patients testing positive for autoantibodies were female, and 67% of all patients were 12 years of age or older. Three patients, 1 with acute ITP and 1 with chronic ITP, had insignificant abnormal thyroid function tests (these children had minimally elevated T3 with otherwise normal thyroid function, and none of these children had autoantibodies). No patients included in the study tested positive for HIV. Our results suggest that patients with acute ITP who also have other autoantibodies may be more likely to develop chronic ITP than those lacking these autoantibodies. Larger studies are needed to determine whether the presence of ATA or ANA is predictive of clinically significant autoimmune disease.

Diffuse Extreme-Ultraviolet Emission from the Coma Cluster: Evidence for Rapidly Cooling Gases at Submegakelvin Temperatures

The central region of the Coma cluster of galaxies was observed in the energy band from 0.065 to 0.245 kiloelectron volts by the Deep Survey telescope aboard the Extreme Ultraviolet Explorer. A diffuse emission halo of angular diameter approximately 30 arc minutes was detected. The extreme-ultraviolet (EUV) emission level exceeds that expected from the x-ray temperature gas in Coma. This halo suggests the presence of two more phases in the emitting gas, one at a temperature of approximately 2 x 10(6) kelvin and the other at approximately 8 x 10(5) kelvin. The latter phase cools rapidly and, in steady state, would have produced cold matter with a mass of approximately 10(14) solar masses within the EUV halo. Although a similar EUV enhancement was discovered in the Virgo cluster, this detection in Coma applies to a noncooling flow system.

Extreme-Ultraviolet Flux from the Virgo Cluster: Further Evidence for a 500,000-Kelvin Component

A surprising discovery in x-ray astronomy was that clusters of galaxies often contain vast quantities of hot (20 million kelvin) diffuse gas. Substantial diffuse extreme-ultraviolet (EUV) emission has recently been detected in the Virgo cluster of galaxies. Depending on the character of the interstellar medium in our galaxy, this emission could be either an aspect of the hot cluster gas or a previously undetected 500,000-kelvin component. Analysis of the observational data in combination with our current knowledge of the interstellar medium revealed that the EUV flux cannot be an effect of the interstellar medium. Hence, a warm cluster component appears likely.

Pediatric rheumatology clinic populations in the United States: results of a 3 year survey. Pediatric Rheumatology Database Research Group

OBJECTIVE

To describe the patient population referred to pediatric rheumatology centers (PRC) across the US 1992-95; and to compare these results to data on regional PRC populations.

METHODS

A Pediatric Rheumatology Disease Registry was established in 1992. Data on new patients seen at 25 PRC across the US were submitted to the registry for a 36 month period from 1992 through 1995.

RESULTS

A total of 12,939 patients were submitted to the registry. Of these patients, 5245 (40.5%) had rheumatological diagnoses. Patients with juvenile rheumatoid arthritis were the largest group of the patient population (2071 patients-16% of total diagnoses). There were 1568 patients with other forms of childhood arthritis (12%), 1172 with collagen vascular diseases (9%), and 434 with vasculitis (3.3%). Over 50% of the patients had nonrheumatologic diagnoses, including 1577 with idiopathic pain syndromes (12%). Other diagnoses included infections, orthopedic conditions, and malignancies. Fourteen percent of the patients were not given a diagnosis at the time of the initial visit.

CONCLUSION

PRC see a wide variety of patients. Although the majority do have rheumatologic conditions, over 50% of new patients have conditions not autoimmune in origin. Fourteen percent of the patients cannot be diagnosed at the time of their first clinic visit, requiring time to see the evolution of their symptoms before a definitive diagnosis can be assigned.

A technique for sequential measurements of DC neuromagnetic fields

Magnetoencephalography (MEG) has the capability of detecting DC neuromagnetic fields which might arise from migraine, stroke, head trauma, etc. However, such fields are not readily measured in serial fashion for technical reasons, including arbitrary neuromagnetometer baselines, residual DC fields which vary from place to place inside conventional magnetically shielded rooms, and especially the high sensitivity of such measurements to small changes in distance between the probe and head. A technique is described to carry out such measurements by raising and lowering the subject under the probe and calibrating the DC shift against the amplitude of spontaneous activity.

Investigation into the attitudes of general practitioners in Staffordshire to medical audit

OBJECTIVES

To investigate the attitudes of general practitioners to medical audit, and any associations between their attitudes and their personal characteristics.

DESIGN

Postal questionnaire survey. SETTING --Staffordshire, United Kingdom.

SUBJECTS

870 Staffordshire general practitioners.

MAIN MEASURES

Agreement or disagreement and associations between the attitudes to 16 statements about audit and the doctors' personal or practice characteristics--namely, sex, number of years since qualification, practice list size, number of partners, and the practices' experience of audit.

RESULTS

601 Staffordshire general practitioners (69%) responded. There was most agreement with the statements that audit is time consuming (86%), that ongoing training and education is needed (71%), that there is a compulsion applied on doctors to audit (68%), and that extra resources for audit should be provided by the medical audit advisory group (65%). There was considerable disagreement (53% of general practitioners) with the statement that ¿government policy to expect general practitioners to do audit will enhance the population's health.¿ The median response by the 601 general practitioners was four positive responses out of 14 statements about audit (two of the 16 statements could not be graded positive or negative to audit). Women doctors generally had more positive attitudes towards audit, and so had those working with smaller mean list sizes, those in larger partnerships, and those in practices that had carried out audit for a longer time.

CONCLUSIONS

There was a generally negative attitude to medical audit, but it was encouraging that those doctors with the most experience of audit obtained the most job satisfaction from it.

IMPLICATIONS

More effort is needed to convince general practitioners of the value of audit. Without this, attempts to involve other members of the primary care team in multidisciplinary clinical audit are unlikely to be effective. Successful audits that are shown to be cost effective as well as leading to improvements in patient care should be publicised and replicated. A higher proportion of resources should be devoted to audit.

The 0.8 day orbit of the precataclysmic binary EUVE J1016-053

The optical counterpart of the new extreme ultraviolet source EUVE J1016-053 (=RE 1016-053) is known to show intermittent sharp Balmer and HE I emission and traces of an M dwarf associated with a white dwarf optical spectrum. We present extensive optical spectroscopy showing the emission lines vary in velocity and intensity on a period of 0d.78929 +/- 0d.00003. The phase of the emission-line strengths lags that of the velocities by 0.237 +/- 0.013 cycle, consistent with the quarter-cycle offset expected if emission arises from the side of the secondary facing the hot white dwarf. EUVE J1016-053 is another example of an extreme ultraviolet illumination-effect binary, which only recently emerged from a common-envelope phase of binary evolution. Based on spectroscopic measurements and new BVR photometry, we find that the M dwarf secondary's contribution to the combined light is smaller than previously reported, probably because of the difficulty of avoiding contamination from a third star 3".2 distant. The velocity of the weak H II absorption is in antiphase to the emission, suggesting that it originates in the white dwarf photosphere. The mass function implied by the emission-line motion is f(M) = 0.28 +/- 0.08 M solar. Assuming the He II absorption does follow the white dwarf, the mass ratio MWD/MdM is 1.8 +/- 0.5, and the gravitational redshift is 45 +/- 14 km s-1. The modulation of the emission lines suggests the inclination i > 40 degrees, but plausible masses demand this inclination be well above the value.

Audit activity and quality of completed audit projects in primary care in Staffordshire

OBJECTIVES

To survey audit activity in primary care and determine which practice factors are associated with completed audit; to survey the quality of completed audit projects.

DESIGN

From April 1992 to June 1993 a team from the medical audit advisory group visited all general practices; a research assistant visited each practice to study the best audit project. Data were collected in structured interviews.

SETTING

Staffordshire, United Kingdom.

SUBJECTS

All 189 general practices.

MAIN MEASURES

Audit activity using Oxford classification system. Quality of best audit project by assessing choice of topic; participation of practice staff; setting of standards; methods of data collection and presentation of results; whether a plan to make changes resulted from the audit; and whether changes led to the set standards being achieved.

RESULTS

Audit information was available from 169 practices (89%). 44(26%) practices had carried out at least one full audit; 40(24%) had not started audit. Mean scores with the Oxford classification system were significantly higher with the presence of a practice manager (2.7(95% confidence interval 2.4 to 2.9) v 1.2(0.7 to 1.8), p < 0.0001) and with computerisation (2.8(2.5 to 3.1) v 1.4 (0.9 to 2.0), p < 0.0001), organised notes (2.6(2.1 to 3.0) v 1.7(7.2 to 2.2), p = 0.03), being a training practice (3.5(3.2 to 3.8) v 2.1(1.8 to 2.4), p < 0.0001), and being a partnership (2.8(2.6 to 3.0) v 1.5(1.1 to 2.0), p < 0.0001). Standards had been set in 62 of the 71 projects reviewed. Data were collected prospectively in 36 projects and retrospectively in 35. 16 projects entailed taking samples from a study population and 55 from the whole population. 50 projects had a written summary. Performance was less than the standards set or expected in 56 projects. 62 practices made changes as a result of the audit. 35 of the 53 that had reviewed the changes found that the original standards had been reached.

CONCLUSIONS

Evaluation of audit in primary care should include evaluation of the methods used, whether deficiencies were identified, and whether changes were implemented to resolve any problems found.

The Elemental Composition of the Corona of Procyon: Evidence for the Absence of the FIP Effect

The chemical composition of the solar corona is not the same as that of the underlying photosphere. In the corona, elements with a first ionization potential (FIP) of </=10 electron volts (for example, iron, magnesium, silicon, and calcium) are overabundant relative to those with an FIP of >/=10 electron volts (for example, oxygen, neon, and sulfur) by factors of 3 to 10 with respect to the photosphere. The origin of this FIP effect is unknown. The launch of the Extreme Ultraviolet Explorer Satellite (EUVE) opened up the spectroscopic capability required to determine elemental abundances in the coronae of other stars. Spectroscopic observations of the corona of the nearby F5 IV star Procyon obtained with EUVE have yielded estimates of the relative abundances of high- and low-FIP species. The results provide evidence that Procyon, unlike the sun, does not exhibit the FIP effect. Whether the sun or Procyon is more typical of the general late-type stellar population is of fundamental interest to the physics of stellar outer atmospheres and has a bearing on the origin of cosmic rays.

Cytogenetic and flow cytometric analysis of a pancreatoblastoma

A pancreatoblastoma from a 4-year old male was examined by flow cytometric ploidy analysis and cytogenetics. To detect differences within the tumor, the specimen was divided into four portions and sampled separately. Flow analysis revealed that each sample contained a diploid and a tetraploid population of tumor cells. These findings correlated well with the cytogenetic analysis, which also revealed differences in structural rearrangements between samples. A t(13;22)(q10;q10) was the only rearrangement found in near-diploid cells as well as one near-tetraploid line. Other common structural changes in near-tetraploid cells included t(13;13)(q10;q10), i(6p)(p10), and del(1). Chromosomes 1, 6, 13, and 22 were consistently missing from all near-tetraploid cells lines. To our knowledge, this is the first flow cytometric and cytogenetic study of a pancreatoblastoma.

Hip contracture as the presenting sign in children with HLA-B27 arthritis

Five pediatric patients who presented with hip contractures are described. There were 3 boys and 2 girls ranging in age from 7 to 14. None had morning stiffness and one complained of no pain at all. Each had undergone several diagnostic procedures and had seen an average of 2.5 doctors before receiving the diagnosis of arthritis. All were antinuclear antibody negative and HLA-B27 positive, and they had excellent responses to treatment with nonsteroidals and physical therapy. HLA-B27 positive arthritis should be considered in the differential diagnosis of otherwise unexplained hip contractures in children.

First measurement of helium on Mars: implications for the problem of radiogenic gases on the terrestrial planets

108 +/- 11 photons of the martian He 584-angstroms airglow detected by the Extreme Ultraviolet Explorer satellite during a 2-day exposure (January 22-23, 1993) correspond to the effective disk average intensity of 43 +/- 10 Rayleigh. Radiative transfer calculations, using a model atmosphere appropriate to the conditions of the observation and having an exospheric temperature of 210 +/- 20 K, result in a He mixing ratio of 1.1 +/- 0.4 ppm in the lower atmosphere. Nonthermal escape of helium is due to electron impact ionization and pickup of He+ by the solar wind, to collisions with hot oxygen atoms, and to charge exchange with molecular species with corresponding column loss rates of 1.4 x 10(5), 3 x 10(4), and 7 x 10(3) cm-2 sec-1, respectively. The lifetime of helium on Mars is 5 x 10(4) years. The He outgassing rate, coupled with the 40Ar atmospheric abundance and with the K:U:Th ratio measured in the surface rocks, is used as input to a single two-reservoir degassing model which is applied to Mars and then to Venus. A similar model with known abundances of K, U, and Th is applied to Earth. The models for Earth and Mars presume loss of all argon accumulated in the atmospheres during the first billion years by large-scale meteorite and planetesimal impacts. The models show that the degassing coefficients for all three planets may be approximated by function delta = delta (0)(t(0)/t)1/2 with delta (0) = 0/1, 0.04, and 0.0125 Byr-1 for Earth, Venus, and Mars, respectively. After a R2 correction this means that outgassing processes on Venus and Mars are weaker than on Earth by factors of 3 and 30, respectively. Mass ratios of U and Th are almost the same for all three planets, while potassium is depleted by a factor of 2 in Venus and Mars. Mass ratios of helium and argon are close to 5 x 10(-9) and 2 x 10(-8) g/g in the interiors of all three planets. The implications of these results are discussed.

Extreme ultraviolet spectroscopy of PKS 2155-304

We present the extreme ultraviolet (75-110 angstroms) spectrum of the BL Lac object PKS 2155-304, the first spectrum of an extragalactic source obtained with the Extreme Ultraviolet Explorer. The spectrum shows a generally smooth continuum, which can be modeled by a single power law plus interstellar absorption, and possibly an absorption feature at approximately 80 angstroms. The best fit to the data suggests that the EUV spectrum can be interpreted as a simple extrapolation of the X-ray continuum, with an energy index alpha approximately 1.6; however, shallower or steeper power laws with indices between -0.4 and 2.7 cannot be ruled out by the existing EUV data alone. The data provide strong constraints on the interstellar neutral H and He along the line of sight. Using a column density of 1.36 x 10(20) cm-2 for the Galactic neutral hydrogen along the PKS 2155-304 line of sight, the neutral helium column density is constrained to be 9%-10% of the hydrogen amount.

Detection of rotational modulation in the coronal extreme-ultraviolet emission from V711 Tauri?

The RS CVn binary V711 Tauri was observed by the Extreme Ultraviolet Explorer satellite (EUVE) twice during the latter half of 1992, for periods lasting several days. Light curves for the waveband 60-180 angstroms derived from the all-sky survey scanning in August and from a pointed calibration observation made in October both exhibit a modulation of about 40%. The modulation in both data sets is very similar, with minimum flux occurring near orbital phase phi=0.5. Analysis using a two-temperature optically thin plasma emission model reveals that most of the detected extreme ultraviolet (EUV) flux emanates from hot (approximately 10(7) K) coronal plasma. The modulation is probably mostly due to either flare-like activity or to rotational occultation of a long-lived, compact, and especially bright coronal structure on the more active star of the system. The phased data support the latter hypothesis. This coronal structure is then likely to be associated with the persistent spot patterns seen on V711 Tau when using Doppler and photometric surface imaging techniques. Comparison with contemporaneous Stromgren b-band photometry indicates that the optical minimum light leads the EUV maximum light by 90 degrees in phase.

Low density of neutral hydrogen and helium in the local interstellar medium: Extreme Ultraviolet Explorer photometry of the Lyman continuum of the hot white dwarfs MCT 0501-2858, MCT 0455-2812, HZ 43, and GD 153

The first comprehensive sky survey of the extreme ultraviolet (EUV) spectral range performed by the Extreme Ultraviolet Explorer (EUVE) has uncovered a handful of very bright sources at wavelengths longer than the He I 504 angstroms photoionization edge. Among these objects are four white dwarfs with exceptionally low interstellar medium (ISM) column densities along the line of sight. Analysis of EUV photometry of the He-rich DO white dwarf MCT 0501-2858 and the H-rich DA white dwarf MCT 0455-2812 along one line of sight and of the DA white dwarfs HZ 43 and GD 153 near the north Galactic pole indicates that the overall minimum column density of the neutral material centered on the Sun is N(H I)= 0.5-1.0 x 10(18) cm-2. In the case of MCT 0501-2858, EUV photometric measurements provide a clear constraint to the effective temperature (60,000-70,000 K). Given these neutral hydrogen columns, the actual contribution to the density of neutral species from the immediate solar environment (the "local fluff") would only cover a distance of approximately 2-3 pc (assuming an average density n(H I) = 0.1 cm-3) leaving these lines of sight almost entirely within the hot phase of the ISM. A preliminary examination of the complete EUVE long-wavelength survey indicates that these lines of sight are exceptional and set a minimum column density in the solar environment.

Astronomy and the Extreme Ultraviolet Explorer satellite

The extreme ultraviolet wave band (100 to 912 angstroms) was thought until recently to be useless to astronomy, primarily because the opacity of the interstellar medium would prevent observations at these wavelengths. However, the interstellar medium has been found to be markedly inhomogeneous in both density and ionization state and the sun is fortunately located in a region of low extreme ultraviolet opacity. The Extreme Ultraviolet Explorer, launched in June 1992, has surveyed the sky in this wave band and has detected a wide variety of astronomical sources at considerable distances, including some extragalactic objects. Studies in the extreme ultraviolet band have already begun to increase our understanding of the contents of the universe.

Continuous emission source covering the 50-300-A band

We have developed a continuous emission source for use in the soft-x-ray and extreme-UV spectral regions. The source and its characteristics are described.

The SERENDIP piggyback SETI project

The SERENDIP project is an ongoing program of monitoring and processing broadband radio signals acquired by existing radio astronomy observatories. SERENDIP operates in a piggyback mode: it makes use of whatever observing plan (sequence of frequencies, sky coordinates, and polarizations) is under way at its host observatory. Moreover, the SERENDIP data acquisition system, once installed, operates autonomously. This approach makes it possible to obtain large amounts of high quality observing time in a manner that is economical and that does not adversely affect ongoing radio astronomy survey work. The SERENDIP II system has been installed at the NRAO 300-foot telescope at Green Bank, West Virginia, and has operated there for several thousand hours. In this report, we summarize our findings from these observations and describe the present status of the project. Two key elements of SERENDIP are the automated data acquisition system that uses adaptive thresholds and logs only statistically significant peaks in the real-time power spectra, and the subsequent off-line analysis programs that identify and reject a variety of interference signals. Several specific correlations have been identified that offer promise. At present, the development and testing of these interference rejection algorithms is the main thrust of our work.