Comparison of polystyrene scintillator fiber array and monolithic polystyrene for neutron imaging and radiography.

The neutron imaging diagnostic at the National Ignition Facility has been operating since 2011 generating neutron images of deuterium-tritium (DT) implosions at peak compression. The current design features a scintillating fiber array, which allows for high imaging resolution to discern small-scale structure within the implosion. In recent years, it has become clear that additional neutron imaging systems need to be constructed in order to provide 3D reconstructions of the DT source and these additional views need to be on a shorter line of sight. As a result, there has been increased effort to identify new image collection techniques that improve upon imaging resolution for these next generation neutron imaging systems, such as monolithic deuterated scintillators. This work details measurements performed at the Weapons Neutron Research Facility at Los Alamos National Laboratory that compares the radiographic abilities of the fiber scintillator with a monolithic scintillator, which may be featured in a future short line of sight neutron imaging systems.

Qualitative comparison of bremsstrahlung X-rays and 800 MeV protons for tomography of urania fuel pellets.

We present an assessment of x-rays and proton tomography as tools for studying the time dependence of the development of damage in fuel rods. We also show data taken with existing facilities at Los Alamos National Laboratory that support this assessment. Data on surrogate fuel rods have been taken using the 800 MeV proton radiography (pRad) facility at the Los Alamos Neutron Science Center (LANSCE), and with a 450 keV bremsstrahlung X-ray tomography facility. The proton radiography pRad facility at LANSCE can provide good position resolution (<70 µm has been demonstrate, 20 µm seems feasible with minor changes) for tomography on activated fuel rods. Bremsstrahlung x-rays may be able to provide better than 100 µm resolution but further development of sources, collimation, and detectors is necessary for x-rays to deal with the background radiation for tomography of activated fuel rods.

Mass spectral analysis of organic aerosol formed downwind of the Deepwater Horizon oil spill: field studies and laboratory confirmations.

In June 2010, the NOAA WP-3D aircraft conducted two survey flights around the Deepwater Horizon (DWH) oil spill. The Gulf oil spill resulted in an isolated source of secondary organic aerosol (SOA) precursors in a relatively clean environment. Measurements of aerosol composition and volatile organic species (VOCs) indicated formation of SOA from intermediate-volatility organic compounds (IVOCs) downwind of the oil spill (Science2011, 331, doi 10.1126/science.1200320). In an effort to better understand formation of SOA in this environment, we present mass spectral characteristics of SOA in the Gulf and of SOA formed in the laboratory from evaporated light crude oil. Compared to urban primary organic aerosol, high-mass-resolution analysis of the background-subtracted SOA spectra in the Gulf (for short, "Gulf SOA") showed higher contribution of C(x)H(y)O(+) relative to C(x)H(y)(+) fragments at the same nominal mass. In each transect downwind of the DWH spill site, a gradient in the degree of oxidation of the Gulf SOA was observed: more oxidized SOA (oxygen/carbon = O/C ∼0.4) was observed in the area impacted by fresher oil; less oxidized SOA (O/C ∼0.3), with contribution from fragments with a hydrocarbon backbone, was found in a broader region of more-aged surface oil. Furthermore, in the plumes originating from the more-aged oil, contribution of oxygenated fragments to SOA decreased with downwind distance. Despite differences between experimental conditions in the laboratory and the ambient environment, mass spectra of SOA formed from gas-phase oxidation of crude oil by OH radicals in a smog chamber and a flow tube reactor strongly resembled the mass spectra of Gulf SOA (r(2) > 0.94). Processes that led to the observed Gulf SOA characteristics are also likely to occur in polluted regions where VOCs and IVOCs are coemitted.

Early diagnosis of familial nephropathy in English cocker spaniels.

Two litters of English cocker spaniels (ECSs) produced by familial nephropathy (FN) carriers were evaluated to characterize the early features of this disease. Three puppies developed FN. Proteinuria, which began when these puppies were five-to-eight months old, was the first abnormality detected. Proteinuria persisted while each puppy's growth rate slowed, and renal function gradually deteriorated. The interval from onset of proteinuria to development of azotemia was two-to-nine months. Characteristic glomerular capillary basement membrane (GCBM) lesions were seen with transmission electron microscopy (TEM) of renal biopsy specimens obtained during this interval. Ultrastructural GCBM lesions progressed substantially during the interval from biopsy to necropsy. However, routine light microscopic findings did not allow definitive diagnosis of FN in either biopsy or necropsy specimens. Detection of FN can be accomplished by screening at-risk ECSs for proteinuria. Renal biopsies are required to confirm the diagnosis in dogs for which proteinuria cannot be explained otherwise. Percutaneous needle biopsy specimens sufficient for TEM must be used to examine the GCBM to make a definitive diagnosis.

Mammary somatosensory pathways are not required for suckling-mediated inhibition of luteinizing hormone secretion and delay of ovulation in cows.

Four experiments were conducted to evaluate endocrine, lactational, and reproductive features of an experimental animal model employing complete neural disconnection of the udder in beef cows and then to utilize the validated model to study the role of mammary somatosensory pathways in suckling-mediated anovulation. For experiment 1, crossbred beef cows (n = 16) were randomly assigned to suckled/sham-operated control, weaned (calf removed)/sham-operated control, and suckled/mammary-denervated groups between Days 14 and 18 postcalving. Ten additional cows were randomly divided into weaned or suckled unoperated control groups (experiment 2). Complete mammary anesthesia was attained in all denervated cows (experiment 1), but sensory perception was not affected in sham-operated controls. Prolactin release patterns were markedly depressed by denervation; however, oxytocin release, milk production, and calf growth rates were not affected. Although acute sham surgery attenuated weaning-induced increases in LH pulse and ovulation frequency (experiment 1), normal responses to weaning were observed in unoperated controls (experiment 2) as well as in sham-operated cows 1 yr later (experiment 3). Finally, denervated-suckled cows (n = 22) that had been denervated before conception (experiment 4) exhibited LH secretion patterns and mean postpartum intervals to luteal activity similar to those of intact-suckled cows (n = 16). In contrast, the intact-weaned group (n = 16; calves weaned at birth) responded within 2 wk postcalving with an increased frequency of LH pulses, and intervals to onset of luteal activity were shortened compared to those in the other groups. Suckling-mediated anovulation is not dependent upon mammary somatosensory cues.

Effects of transcutaneous thermal and electrical stimulation of the teat on pituitary luteinizing hormone, prolactin and oxytocin secretion in ovariectomized, estradiol-treated beef cows following acute weaning.

The objective of the study was to determine if chronic electrical or thermal stimulation of sensory neurons on the surface of the teat is able to activate pathways that suppress the weaning-induced increase in luteinizing hormone (LH) secretion in beef cows. Treatment groups (n = 5 per group) consisted of: 1) control suckled (CS); 2) weaned plus electrical stimulation of the teat (ESTT); 3) weaned plus electrical stimulation of the tail (ESTL); 4) weaned plus thermal stimulation of the teat (TTT); 5) weaned plus thermal stimulation of the tail (TTL) and 6) weaned (WN). Cows were ovariectomized on Day 5 post partum (PP) and were treated with estradiol-17beta to maintain a constant tonic baseline. Beginning on Days 17 to 21 post partum, cows were suckled by their own calf (control), weaned or weaned and electrically or thermally stimulated for 10 minutes every 6 hours for 4 days. Chronic transcutaneous electrical and thermal stimulation of the teat or tail failed to impede the unambiguous rise (P < 0.001) in LH pulse frequency and amplitude following weaning. Positive and negative feedback of estradiol on LH secretion was not affected by treatments. Relatively consistent episodes of oxytocin and prolactin release were observed following control-suckling, but responses to electrical and thermal stimulation were inconsistent. Chronic electrical or thermal stimulation of teat-specific or nonspecific loci did not attenuate heightened secretion of LH after weaning. The results are further evidence against a role for mammary somatosensory neurons in the suckling-mediated inhibition of LH secretion.

Intraluminal bypass device for arterial surgery.

Over 50,000 artificial grafts are implanted every year in the United States. Present surgical procedures require either bypass or clamping off of the vessel to be replaced. Complications of these techniques include aneurysms and left ventricular overload. In addition, for aortic procedures paraplegia or even death can occur. A simple surgical procedure that does not require cardiopulmonary bypass, external shunts, or cross-clamping was developed and tested in dogs. An intraluminal bypass device was developed to allow blood to flow through the aorta to the lower limbs during the procedure. Blood flow stoppage was minimized, which should lead to a reduction of morbidity and mortality.

Augmenting retention of a removable partial denture repair.

A simple technique improves the retention of a tooth to be added to an existing removable partial denture. The procedure includes placing a small contoured wire into the space provided for the acrylic resin repairing material.

Brain stem auditory-evoked responses in the dog.

Brain stem auditory-evoked responses (BAER) were recorded from 58 dogs that did not have a known history of hearing problems. The BAER wave forms had an overall mean amplitude approximately 3.0 microV and typically consisted of a series of 4 to 5 vertex-positive peaks (peaks I through V). When acoustic clicks having intensities of 60-dB hearing level (decibels relative to the subjective hearing threshold) were used as stimuli, peak I had a latency of 1.49 +/- 0.13 ms; peak II, 2.32 +/- 0.14 ms; peak III, 3.01 +/- 0.25 ms; peak IV, 4.22 +/- 0.27 ms; and peak V, 5.55 +/- 0.37 ms. Latency values were influenced by a number of nonpathologic factors, including stimulus intensity and the body temperature of the dog. As stimulus intensity was decreased, there was a lengthening of the latency of each peak coupled with a decrease in the overall amplitude of BAER. Decreases in rectal temperature caused a similar lengthening of peak latencies. Age may have an influence on BAER, but under the conditions of the present study, the effect was not significant.

L-pyroglutamate: an alternate neurotoxin for a rodent model of Huntington's disease.

Intrastriatal injections of L-Pyroglutamate (L-PGA) in mice produced behavioral and neuropathological effects that resemble in part the kainate-injected rat striatal model of Huntington's Disease (HD). The behavioral responses induced after unilateral injections of L-PGA included circling, postural asymmetry of head and trunk and possible dyskinesias. The neuropil in the injected striatum contained dilated profiles, degenerating neurons and oligodendroglia, and numerous phagocytic microglial-like cells. A dose response relation existed. The size of the lesion (expressed as a percent volume of the striatum destroyed) ranged from 1 +/- 0.18% at 0.02 mumoles to 20.2 +/- 3.97% at 200 mumoles L-PGA (pH = 7.3). L-PGA is a weak neurotoxin when compared to kainic acid. Several factors raise interest in the possible role of L-PGA in HD, including the recently reported elevated plasma levels of L-PGA in some HD patients, and these considered in the discussion.