Unusual Near-Horizon Cosmic-Ray-like Events Observed by ANITA-IV.

ANITA's fourth long-duration balloon flight in 2016 detected 29 cosmic-ray (CR)-like events on a background of 0.37_{-0.17}^{+0.27} anthropogenic events. CRs are mainly seen in reflection off the Antarctic ice sheets, creating a phase-inverted waveform polarity. However, four of the below-horizon CR-like events show anomalous noninverted polarity, a p=5.3×10^{-4} chance if due to background. All anomalous events are from locations near the horizon; ANITA-IV observed no steeply upcoming anomalous events similar to the two such events seen in prior flights.

Accelerator Measurements of Magnetically Induced Radio Emission from Particle Cascades with Applications to Cosmic-Ray Air Showers.

For 50 years, cosmic-ray air showers have been detected by their radio emission. We present the first laboratory measurements that validate electrodynamics simulations used in air shower modeling. An experiment at SLAC provides a beam test of radio-frequency (rf) radiation from charged particle cascades in the presence of a magnetic field, a model system of a cosmic-ray air shower. This experiment provides a suite of controlled laboratory measurements to compare to particle-level simulations of rf emission, which are relied upon in ultrahigh-energy cosmic-ray air shower detection. We compare simulations to data for intensity, linearity with magnetic field, angular distribution, polarization, and spectral content. In particular, we confirm modern predictions that the magnetically induced emission in a dielectric forms a cone that peaks at the Cherenkov angle and show that the simulations reproduce the data within systematic uncertainties.

Observation of ultrahigh-energy cosmic rays with the ANITA balloon-borne radio interferometer.

We report the observation of 16 cosmic ray events with a mean energy of 1.5 × 10¹9 eV via radio pulses originating from the interaction of the cosmic ray air shower with the Antarctic geomagnetic field, a process known as geosynchrotron emission. We present measurements in the 300-900 MHz range, which are the first self-triggered, first ultrawide band, first far-field, and the highest energy sample of cosmic ray events collected with the radio technique. Their properties are inconsistent with current ground-based geosynchrotron models. The emission is 100% polarized in the plane perpendicular to the projected geomagnetic field. Fourteen events are seen to have a phase inversion due to reflection of the radio beam off the ice surface, and two additional events are seen directly from above the horizon. Based on a likelihood analysis, we estimate angular pointing precision of order 2° for the event arrival directions.

New limits on the ultrahigh energy cosmic neutrino flux from the ANITA experiment.

We report initial results of the first flight of the Antarctic Impulsive Transient Antenna (ANITA-1) 2006-2007 Long Duration Balloon flight, which searched for evidence of a diffuse flux of cosmic neutrinos above energies of E(nu) approximately 3 x 10(18) eV. ANITA-1 flew for 35 days looking for radio impulses due to the Askaryan effect in neutrino-induced electromagnetic showers within the Antarctic ice sheets. We report here on our initial analysis, which was performed as a blind search of the data. No neutrino candidates are seen, with no detected physics background. We set model-independent limits based on this result. Upper limits derived from our analysis rule out the highest cosmogenic neutrino models. In a background horizontal-polarization channel, we also detect six events consistent with radio impulses from ultrahigh energy extensive air showers.

Observations of the Askaryan effect in ice.

We report on observations of coherent, impulsive radio Cherenkov radiation from electromagnetic showers in solid ice. This is the first observation of the Askaryan effect in ice. As part of the complete validation process for the ANITA experiment, we performed an experiment at the Stanford Linear Accelerator Center in June 2006 using a 7.5 metric ton ice target. We measure for the first time the large-scale angular dependence of the radiation pattern, a major factor in determining the solid-angle acceptance of ultrahigh-energy neutrino detectors.

Constraints on cosmic neutrino fluxes from the Antarctic Impulsive Transient Antenna experiment.

We report new limits on cosmic neutrino fluxes from the test flight of the Antarctic Impulsive Transient Antenna (ANITA) experiment, which completed an 18.4 day flight of a prototype long-duration balloon payload, called ANITA-lite, in early 2004. We search for impulsive events that could be associated with ultrahigh energy neutrino interactions in the ice and derive limits that constrain several models for ultrahigh energy neutrino fluxes and rule out the long-standing -burst model.

Experimental limit on the cosmic diffuse ultrahigh energy neutrino flux.

We report results from 120 h of live time with the Goldstone lunar ultrahigh energy neutrino experiment (GLUE). The experiment searches for < or = 10 ns microwave pulses from the lunar regolith, appearing in coincidence at two large radio telescopes separated by 22 km and linked by optical fiber. Such pulses would arise from subsurface electromagnetic cascades induced by interactions of > or = 100 EeV (1 EeV = 10(18) eV neutrinos in the lunar regolith. No candidates are yet seen, and the implied limits constrain several current models for ultrahigh energy neutrino fluxes.

Observation of the Askaryan effect: coherent microwave Cherenkov emission from charge asymmetry in high-energy particle cascades.

We present the first direct experimental evidence for the charge excess in high-energy particle showers and corresponding radio emission predicted nearly 40 years ago by Askaryan. We directed picosecond pulses of GeV bremsstrahlung photons at the SLAC Final Focus Test Beam into a 3.5 ton silica sand target, producing electromagnetic showers several meters long. A series of antennas spanning 0.3 to 6 GHz detected strong, subnanosecond radio-frequency pulses produced by the showers. Measurements of the polarization, coherence, timing, field strength vs shower depth, and field strength vs frequency are completely consistent with predictions. These measurements thus provide strong support for experiments designed to detect high-energy cosmic rays such as neutrinos via coherent radio emission from their cascades.

Childhood asthma and passive smoking. Urinary cotinine as a biomarker of exposure.

To assess the relationship between passive smoking and asthma, we investigated (1) whether passive smoking was more prevalent among asthmatic than control children and (2) whether exposure to tobacco smoke was higher in acute asthma than in nonacute asthma. Three groups were recruited into a case-control study: 72 acute asthmatic children from the emergency room (ER), 35 nonacute asthmatic children from the asthma clinic, and 121 control children from the ER. Both questionnaire and urinary cotinine/creatinine ratio (CCR) were used to assess passive smoking. Levels of CCR greater than or equal to 30 ng/mg were used to identify children exposed at home. Mean CCR was also computed. Acute and nonacute asthmatic children had similar prevalences of passive smoking at home. Acute cases showed a higher mean CCR than nonacute cases, but this was not significant. In comparing all asthmatic to control children, smoking by the maternal caregiver was more prevalent among asthmatic children (odds ratio OR = 2.0, 95% CI 1.1, 3.4). This was confirmed by CCR greater than or equal to 30 ng/mg (OR = 1.9, 95% CI 1.04, 3.35) and by the difference in mean CCR (43.6 versus 25.8 ng/mg, p = 0.06). We conclude that smoking by the maternal caregiver is associated with clinically significant asthma in children. We could not show that it is a trigger of acute asthma attacks.

Cryptosporidium infection in acquired immunodeficiency syndrome: not always a poor prognosis.

Chronic diarrhea and malabsorption accompanied by simultaneous infection with the protozoa Giardia lamblia and Cryptosporidium occurred in a 22-year-old homosexual man with antibody to human immunodeficiency virus (HIV). Small bowel biopsy demonstrated total villous atrophy and marked mononuclear infiltration in the lamina propria simulating celiac disease. Treatment with metronidazole resulted in resolution of diarrhea, clearance of parasites, and marked improvement in small bowel histology. Although diarrhea and malabsorption in immunocompromised patients with cryptosporidiosis are regarded as ominous, our patient remained disease free for the next 3 years. Thus, infection with Cryptosporidium in patients with HIV does not always lead to intractable diarrhea or death.

Isolated ventral pancreatitis in a patient with pancreas divisum.

A previously healthy 22-yr-old woman was found to have chronic pancreatitis restricted to the ventral pancreas in association with pancreas divisum. When conservative treatment failed, sphincteroplasty of both papillae was performed with good results. This well-documented case represents a clear exception to the commonly held concept that obstruction of the dorsal duct is the essential pathogenic factor in the development of pancreatitis associated with pancreas divisum. The importance of visualizing both the dorsal and ventral pancreatic ducts to direct therapy for patients with idiopathic pancreatitis is discussed. Theories of the pathogenesis of concomitant pancreatitis and pancreas divisum are reviewed.

Impact of age, sex, race, and functional complaints on hydrogen (H2) production.

In order to evaluate factors that may influence H2 generation, the effects of age, sex, race, and functional complaints on breath H2 were studied in 62 subjects. These included 34 young hospital employees, 17 healthy ambulatory elderly subjects, and 11 patients with functional bowel disease. The ability to produce H2 was defined by an increase in breath H2 to greater than 20 parts per million within 4 hr of ingesting 10 g of the nonabsorbable sugar lactulose. Overall, 21% of subjects were nonproducers, and the incidence of nonproduction did not vary among the groups. The elderly subjects had significantly greater breath H2 concentrations than the younger subjects at 150 minutes (P less than 0.05). Sex, race, and functional complaints did not influence H2 production. These findings indicate that patient's age and potential inability to make H2 need to be considered in the routine interpretation of H2 breath tests.

Colocutaneous fistula: an unusual complication of percutaneous endoscopic gastrostomy.

We describe an unusual complication of percutaneous endoscopic gastrostomy, the formation of a colocutaneous fistula. The complication resulted from penetration of both the colon and stomach at the time of catheter placement. This problem went unrecognized for several months until the feeding catheter was removed, and its replacement could be advanced only as far as the colon. Complications of percutaneous endoscopic gastrostomy are reviewed, and the problem of gastrocolic fistula formation secondary to gastrostomy placement is discussed.

Fulminant amebic colitis in a homosexual man.

This report describes a case of fulminant amebic colitis leading to perforation and death in a 35-yr-old homosexual man. Although Entamoeba histolytica may be isolated from stool specimens in 20 to 30% of selected homosexual populations, reports of severe or invasive disease are rare. Some workers have suggested that amebae are only passive colonizers of the colon in homosexual men. In our patient, pathological examination confirmed the presence of extensive colitis with penetration of amebae through the bowel wall. Pertinent data concerning pathogenicity of E. histolytica in homosexuals are reviewed and the public health implications of a virulent strain of amebae are discussed.

Feeding tube-induced pneumothorax.

A case of accidental bronchial perforation by the metal stylet of a silastic feeding tube is reported. The misplacement of the feeding tube resulted in a pneumothorax. This is a previously unreported complication of enteral feeding in adults. Pulmonary complications of enteral feeding and recommendations for prevention of these complications are discussed.

Scanning electron microscope study of the junction between restorations and gingival cavosurface margins.

This study demonstrates a definite interfacial void between the cervical margins of the tooth preparation and gold inlay, composite resin, and amalgam restorations. In addition, these marginal defects permit plaque formation within them. Furthermore, microleakage may be a complicating factor in this lack of fit. Restorations which may be "clinically acceptable" may not, in fact, be ideal because of the properties of the restorative materials. It would seem desirable, therefore, to encourage the development of new restorative materials that will bond to the tooth surface.