Discovery of a 3.6-hr Eclipsing Luminous X-Ray Binary in the Galaxy NGC 4214

We report the discovery of an eclipsing X-ray binary with a 3.62-hr period within 24" of the center of the dwarf starburst galaxy NGC 4214. The orbital period places interesting constraints on the nature of the binary, and allows for a few very different interpretations. The most likely possibility is that the source lies within NGC 4214 and has an X-ray luminosity of up to 7 e38 ergs/s. In this case the binary may well be comprised of a naked He-burning donor star with a neutron-star accretor, though a stellar-mass black-hole accretor cannot be completely excluded. There is no obvious evidence for a strong stellar wind in the X-ray orbital light curve that would be expected from a massive He star; thus, the mass of the He star should be <3-4 solar masses. If correct, this would represent a new class of very luminous X-ray binary -- perhaps related to Cyg X-3. Other less likely possibilities include a conventional low-mass X-ray binary that somehow manages to produce such a high X-ray luminosity and is apparently persistent over an interval of years; or a foreground AM Her binary of much lower luminosity that fortuitously lies in the direction of NGC 4214. Any model for this system must accommodate the lack of an optical counterpart down to a limiting magnitude of 22.6 in the visible.Comment: 7 pages, ApJ accepted versio

Electron paramagnetic resonance (EPR) in medical dosimetry

This paper describes the fundamentals of electron paramagnetic resonance (EPR) and its application to retrospective measurements of clinically significant doses of ionizing radiation. X-band is the most widely used in EPR dosimetry because it represents a good compromise between sensitivity, sample size and water content in the sample. Higher frequency bands (e.g., W and Q) provide higher sensitivity, but they are also greatly influenced by water content. L and S bands can be used for EPR measurements in samples with high water content but they are less sensitive than X-band. Quality control for therapeutic radiation facilities using X-band EPR spectrometry of alanine is also presented

Simulation of Heavily Irradiated Silicon Pixel Sensors and Comparison with Test Beam Measurements

Charge collection measurements performed on heavily irradiated p-spray DOFZ pixel sensors with a grazing angle hadron beam provide a sensitive determination of the electric field within the detectors. The data are compared with a complete charge transport simulation of the sensor which includes signal trapping and charge induction effects. A linearly varying electric field based upon the standard picture of a constant type-inverted effective doping density is inconsistent with the data. A two-trap double junction model implemented in the ISE TCAD software can be tuned to produce a doubly-peaked electric field which describes the data reasonably well. The modeled field differs somewhat from previous determinations based upon the transient current technique. The model can also account for the level of charge trapping observed in the data.Comment: 8 pages, 11 figures. Talk presented at the 2004 IEEE Nuclear Science Symposium, October 18-21, Rome, Italy. Submitted to IEEE Transactions on Nuclear Scienc

Full-Shell X-Ray Optics Development at NASA Marshall Space Flight Center

NASAs Marshall Space Flight Center (MSFC) maintains an active research program toward the development of high-resolution, lightweight, grazing-incidence x-ray optics to serve the needs of future x-ray astronomy missions such as Lynx. MSFC development efforts include both direct fabrication (diamond turning and deterministic computer-controlled polishing) of mirror shells and replication of mirror shells (from figured, polished mandrels). Both techniques produce full-circumference monolithic (primary + secondary) shells that share the advantages of inherent stability, ease of assembly, and low production cost. However, to achieve high-angular resolution, MSFC is exploring significant technology advances needed to control sources of figure error including fabrication- and coating-induced stresses and mounting-induced distortions

Adjuvant-free immunization with infective filarial larvae as lymphatic homing antigen carriers

International audienceControlled infection with intestinal nematodes has therapeutic potential for preventing the symptoms of allergic and autoimmune diseases. Here, we engineered larvae of the filarial nematode Litomosoides sigmodontis as a vaccine strategy to induce adaptive immunity against a foreign, crosslinked protein, chicken egg ovalbumin (OVA), in the absence of an external adjuvant. The acylation of filarial proteins with fluorescent probes or biotin was not immediately detrimental to larval movement and survival, which died 3 to 5 days later. At least some of the labeled and skin-inoculated filariae migrated through lymphatic vessels to draining lymph nodes. The immunization potential of OVA-biotin-filariae was compared to that of an OVA-bound nanoparticulate carrier co-delivered with a CpG adjuvant in a typical vaccination scheme. Production of IFNγ and TNFα by restimulated CD4+ cells but not CD8+ confirmed the specific ability of filariae to stimulate CD4+ T cells. This alternative method of immunization exploits the intrinsic adjuvancy of the attenuated nematode carrier and has the potential to shift the vaccination immune response towards cellular immunity

Unveiling the nature of the highly obscured AGN in NGC5643 with XMM-Newton

We present results from an XMM-Newton observation of the nearby Seyfert 2 galaxy NGC5643. The nucleus exhibits a very flat X-ray continuum above 2 keV, together with a prominent K-alpha fluorescent iron line. This indicates heavy obscuration. We measure an absorbing column density N_H in the range 6-10 x 10^{23} atoms/cm/cm, either directly covering the nuclear emission, or covering its Compton-reflection. In the latter case, we might be observing a rather unusual geometry for the absorber, whereby reflection from the inner far side of a torus is in turn obscured by its near side outer atmosphere. The nuclear emission might be then either covered by a Compton-thick absorber, or undergoing a transient state of low activity. A second source (christened "X-1" in this paper) at the outskirts of NGC5643 optical surface outshines the nucleus in X-rays. If belonging to NGC5643, it is the third brightest (L_X ~ 4 x 10^{40} erg/s) known Ultra Luminous X-ray source. Comparison with past large aperture spectra of NGC 5643 unveils dramatic X-ray spectral changes above 1 keV. We interpret them as due to variability of the active nucleus and of source X-1 intrinsic X-ray powers by a factor >10 and 5, respectively.Comment: 11 LATEX pages, 12 figures, to appear in Monthly Notices of the Royal Astronomical Societ

X-ray properties of radio-selected star forming galaxies in the Chandra-COSMOS survey

X-ray surveys contain sizable numbers of star forming galaxies, beyond the AGN which usually make the majority of detections. Many methods to separate the two populations are used in the literature, based on X-ray and multiwavelength properties. We aim at a detailed test of the classification schemes and to study the X-ray properties of the resulting samples. We build on a sample of galaxies selected at 1.4 GHz in the VLA-COSMOS survey, classified by Smolcic et al. (2008) according to their optical colours and observed with Chandra. A similarly selected control sample of AGN is also used for comparison. We review some X-ray based classification criteria and check how they affect the sample composition. The efficiency of the classification scheme devised by Smolcic et al. (2008) is such that ~30% of composite/misclassified objects are expected because of the higher X-ray brightness of AGN with respect to galaxies. The latter fraction is actually 50% in the X-ray detected sources, while it is expected to be much lower among X-ray undetected sources. Indeed, the analysis of the stacked spectrum of undetected sources shows, consistently, strongly different properties between the AGN and galaxy samples. X-ray based selection criteria are then used to refine both samples. The radio/X-ray luminosity correlation for star forming galaxies is found to hold with the same X-ray/radio ratio valid for nearby galaxies. Some evolution of the ratio may be possible for sources at high redshift or high luminosity, tough it is likely explained by a bias arising from the radio selection. Finally, we discuss the X-ray number counts of star forming galaxies from the VLA- and C-COSMOS surveys according to different selection criteria, and compare them to the similar determination from the Chandra Deep Fields. The classification scheme proposed here may find application in future works and surveys.Comment: 15 pages, 7 figures, 3 table

The Identification of the X-ray Counterpart to PSR J2021+4026

We report the probable identification of the X-ray counterpart to the gamma-ray pulsar PSR J2021+4026 using imaging with the Chandra X-ray Observatory ACIS and timing analysis with the Fermi satellite. Given the statistical and systematic errors, the positions determined by both satellites are coincident. The X-ray source position is R.A. 20h21m30.733s, Decl. +40 deg 26 min 46.04sec (J2000) with an estimated uncertainty of 1.3 arsec combined statistical and systematic error. Moreover, both the X-ray to gamma-ray and the X-ray to optical flux ratios are sensible assuming a neutron star origin for the X-ray flux. The X-ray source has no cataloged infrared-to-visible counterpart and, through new observations, we set upper limits to its optical emission of i' >23.0 mag and r' > 25.2mag. The source exhibits an X-ray spectrum with most likely both a powerlaw and a thermal component. We also report on the X-ray and visible light properties of the 43 other sources detected in our Chandra observation.Comment: Accepted for publication in the Astrophysical Journa

Risk and Clinical Risk Factors associated With Late Lower Cranial Neuropathy in Long-Term oropharyngeal Squamous Cell Carcinoma Survivors

IMPORTANCE: Lower cranial neuropathy (LCNP) is a rare, but permanent, late effect of radiotherapy and other cancer therapies. Lower cranial neuropathy is associated with excess cancer-related symptoms and worse swallowing-related quality of life. Few studies have investigated risk and clinical factors associated with late LCNP among patients with long-term survival of oropharyngeal squamous cell carcinoma (OPSCC survivors). OBJECTIVE: to estimate the cumulative incidence of and identify clinical factors associated with late LCNP among long-term OPSCC survivors. DESIGN, SETTING, AND PARTICIPANTS: This single-institution cohort study included disease-free adult OPSCC survivors who completed curative treatment from January 1, 2000, to December 31, 2013. Exclusion criteria consisted of baseline LCNP, recurrent head and neck cancer, treatment at other institutions, death, and a second primary, persistent, or recurrent malignant neoplasm of the head and neck less than 3 months after treatment. Median survival of OPSCC among the 2021 eligible patients was 6.8 (range, 0.3-18.4) years. Data were analyzed from October 12, 2019, to November 13, 2020. MAIN OUTCOMES AND MEASURES: Late LCNP events were defined by neuropathy of the glossopharyngeal, vagus, and/or hypoglossal cranial nerves at least 3 months after cancer therapy. Cumulative incidence of LCNP was estimated using the Kaplan-Meier method, and multivariable Cox proportional hazards models were fit. RESULTS: Among the 2021 OPSCC survivors included in the analysis of this cohort study (1740 [86.1%] male; median age, 56 [range, 28-86] years), 88 (4.4%) were diagnosed with late LCNP, with median time to LCNP of 5.4 (range, 0.3-14.1) years after treatment. Cumulative incidence of LCNP was 0.024 (95% CI, 0.017-0.032) at 5 years, 0.061 (95% CI, 0.048-0.078) at 10 years, and 0.098 (95% CI, 0.075-0.128) at 15 years of follow-up. Multivariable Cox proportional hazards regression identified T4 vs T1 classification (hazard ratio [HR], 3.82; 95% CI, 1.85-7.86) and accelerated vs standard radiotherapy fractionation (HR, 2.15; 95% CI, 1.34-3.45) as independently associated with late LCNP status, after adjustment. Among the subgroup of 1986 patients with nonsurgical treatment, induction chemotherapy regimens including combined docetaxel, cisplatin, and fluorouracil (TPF) (HR, 2.51; 95% CI, 1.35-4.67) and TPF with cetuximab (HR, 5.80; 95% CI, 1.74-19.35) along with T classification and accelerated radiotherapy fractionation were associated with late LCNP status after adjustment. CONCLUSIONS AND RELEVANCE: This single-institution cohort study found that, although rare in the population overall, cumulative risk of late LCNP progressed to 10% during the survivors\u27 lifetime. As expected, clinical factors associated with LCNP primarily reflected greater tumor burden and treatment intensity. Further efforts are necessary to investigate risk-reduction strategies as well as surveillance and management strategies for this disabling late effect of cancer treatment

Sars-Cov-2 Serostatus and Covid-19 Illness Characteristics By Variant Time Period in Non-Hospitalized Children and adolescents

OBJECTIVE: to describe COVID-19 illness characteristics, risk factors, and SARS-CoV-2 serostatus by variant time period in a large community-based pediatric sample. DESIGN: Data were collected prospectively over four timepoints between October 2020 and November 2022 from a population-based cohort ages 5 to 19 years old. SETTING: State of Texas, USA. PARTICIPANTS: Participants ages 5 to 19 years were recruited from large pediatric healthcare systems, Federally Qualified Healthcare Centers, urban and rural clinical practices, health insurance providers, and a social media campaign. EXPOSURE: SARS-CoV-2 infection. MAIN OUTCOME(S) AND MEASURE(S): SARS-CoV-2 antibody status was assessed by the Roche Elecsys RESULTS: Over half (57.2%) of the sample (N = 3911) was antibody positive. Symptomatic infection increased over time from 47.09% during the pre-Delta variant time period, to 76.95% during Delta, to 84.73% during Omicron, and to 94.79% during the Omicron BA.2. Those who were not vaccinated were more likely (OR 1.71, 95% CI 1.47, 2.00) to be infected versus those fully vaccinated. CONCLUSIONS: Results show an increase in symptomatic COVID-19 infection among non-hospitalized children with each progressive variant over the past two years. Findings here support the public health guidance that eligible children should remain up to date with COVID-19 vaccinations