Multiwire proportional chamber system of the Fermilab single arm spectrometer.

We describe a system of two groups of multiwire proportional chambers and its special purpose interface used in the Single Arm Spectrometer (SAS) facility at Fermilab. The first set measures the coordinates of the fast particle going into the spectrometer arm with a space resolution down to +/-0.5 mm. The second set, close to the target, measures the multiplicity and angular distributions of charged particles coming from the interaction. The chambers of this set have three sensitive planes with wires at 120 degrees in the same gas volume to measure three coordinates for each physical point, two readout channels per wire to minimize the inefficiency due to the very high flux and insensitive regions at the center of the chambers where they are crossed by the beam.

Comparison of intra-operative analgesia provided by intravenous regional anesthesia or brachial plexus block for pancarpal arthrodesis in dogs.

The aim of this study was to compare intravenous regional anesthesia (IVRA) and brachial plexus block (BPB) for intra-operative analgesia in dogs undergoing pancarpal arthrodesis (PA). Twenty dogs scheduled for PA were intramuscularly sedated with acepromazine (0.03 mg/kg), general anesthesia was intravenously (IV) induced with thiopental (10 mg/kg) and, after intubation, maintained with isoflurane in oxygen. In 10 dogs (GIVRA) IVRA was performed on the injured limb administering 0.6 ml/kg of 0.5% lidocaine. In 10 dogs (GBPB) the BPB was performed at the axillary level with the help of a nerve stimulator and 0.3 ml/kg of a 1:1 solution of 2% lidocaine and 1% ropivacaine was injected. During surgery fentanyl (0.002 mg/kg IV) was administered if there was a 15% increase of HR and/or MAP compared to the values before surgical stimulation. All the standard cardiovascular and respiratory parameters were continuously monitored during surgery. The duration of surgery and the time of extubation were recorded. Data were compared with a 1-way ANOVA test (P<0.05). No patients required fentanyl administration during surgery. All the recorded parameters were similar in the two groups. The two techniques were similar in providing intra-operative analgesia in dogs undergoing orthopaedic surgery.

Alveolar recruiting maneuver in dogs under general anesthesia: effects on alveolar ventilation, gas exchange, and respiratory mechanics.

The aim of this study was to evaluate the effects of a recruiting maneuver (RM) on lung aeration, gas exchange, and respiratory mechanics during general anesthesia in mechanically ventilated dogs. A thoracic computed tomography (CT) scan, an arterial blood sample, and measurement of respiratory mechanics were performed 10 min before (baseline) and both 5 and 30 min after a vital capacity RM in 10 dogs under general anesthesia. The RM was performed by inflating the lung at 40 cm H(2)O for 20 s. Lung aeration was estimated by analyzing the radiographic attenuation of the CT images. Lung aeration and gas exchange improved significantly 5 min after the RM compared to baseline and returned to values similar to baseline by 30 min. Static lung compliance was not significantly affected by the RM. An RM induces a temporary improvement in lung function in healthy dogs under general anesthesia.

[Biomechanical models of the human skull: stability of various segments in three simulations]. / Modello biomeccanico del cranio umano; stabilita' dei diversi segmenti in tre simulazioni.

Three simulations by a computer model of human skull, implemented on finite elements and virtual works principles, were performed by a 15 Kg loading of the structure according rules of mechanical stresses of chewing. First model had all elements in place, second was without vault and third was without orbital walls. Stability of the structure was evaluated in terms of "instability coefficient" as an index of sum of moduli and number of considered nodes such moduli give spatial displacement of nodes after loading and deformation of shell elements. All parts of the structure are involved in ensuring stability so that it decreases as different segments or elements are not considered during simulation. The vault plays a great role in total stability of the model while orbital walls appear as a mechanical link between anterior (frontal) and posterior (occipital) parts of the model.

[Biomechanical model simulating the evolutionary morphology of the human cranium. Preliminary note]. / Modello biomeccanico di simulazione della morfologia evolutiva del cranio umano -nota preliminare-.

A simulation strategy as been pointed in order to evaluate the fate of the chewing stresses exerting at the molars. The human skull's structure is considered as analog of a built-up arch and/or vault system well adapted for such mechanical fitting. The shallow shell routine of Ices-STRUDL program was worked out. The preliminary results are reported.

[Biomechanical simulation model of the developmental morphology of the human skull. Further observations on the model construction]. / Modello biomeccanico di simulazione della morfologia evolutiva del cranio umano. Ulteriori osservazioni circa la costruzione del modello.

The implementation of a software simulation of a biomechanical model of the human skull, requires a high complexity construction made by a different ellipsoids and planes. At present our model is made by a facial, post-facial, occipital and palatal ellipsoids, a basal plane with a hole, walls of the nasal cavity and conic walls of the orbital cavities. Dimension of the model resemble closely an adult human skull. The physical constants given for the constituting material those of compact bone. The cavity of the model is closed except for the hole of the basal plane and for the posterior openings of the orbital cavities. The number of elements of the model is 416.

[Sleep in a case of hemiballism]. / Evoluzione del sonno in un caso di emiballismo.

Sleep spindles abnormalities in extrapyramidal disorders have already been reported, but in the unilateral syndromes the data are unclear and inconclusive. In the attempt to clarify the problem we describe nocturnal sleep in a patient with hemiballism due to an ischemic damage of the subthalamic nucleus. The patient improved after one month haloperidol therapy and her unilateral (right) hyperkinesias disappeared. Electropolygraphic records (EEG, EOG, EMG of chin muscles, ECG) during spontaneous nocturnal sleep were obtained before therapy and after one month haloperidol treatment. The EEGs from bilateral fronto-central derivations were also recorded on magnetic tape to allow spectral analysis and automatic spindle detection by means of digital filtering. The pattern of spindle appearance rate for each stage 2 and 3 NonREM sleep in each night was investigated. We obtained: spindling index, that is the ratio between total spindle duration and sleep stage length, the mean number of spindle bursts/min, the average duration of sleep spindles, the mean amplitude, the mean time between spindles. Before therapy polygraphic records showed short total sleep time, a prolonged sleep latency, the lack of slow waves sleep and of REM sleep. After haloperidol treatment these parameters improved: total sleep time was longer, sleep latency shorter, slow waves sleep and REM sleep appeared. Before treatment spindle activity predominated in the left hemisphere - homolaterally to the subthalamic nucleus damage -, where the spindling index was higher, the mean number of spindle bursts/min larger, the mean time between spindles lower. After therapy, when hemisomatic hyperkinesias disappeared, spindle activity turned similar in the two hemispheres, since it decreased in the left hemisphere and it was unchanged in the right one.(ABSTRACT TRUNCATED AT 250 WORDS)

Curdlan sulfate (CRDS) in a 21-day intravenous tolerance study in human immunodeficiency virus (HIV) and cytomegalovirus (CMV) infected patients: indication of anti-CMV activity with low toxicity.

This study evaluated tolerance (and possible efficacy) for 21 days of i.v. administration at three dose levels of curdlan sulfate (CRDS) (a semisynthetic sulfated polysaccharide), administered over 30 minutes, in HIV and CMV (in some cases) infected individuals with CD4 levels < 500 cells/mm3. Half of the subjects were previously treated with reverse transcriptase inhibitors (RTI) (which were continued during the CRDS administration) and half the patients had no prior RTI treatment. Evaluation of other sulfated polysaccharides in HIV had been discontinued due to side effects and lack of activity. Three groups of HIV patients (also including subsets with CMV infection) were treated separately with 50 mg/70 Kg, 100 mg/70 Kg and 200 mg/70 Kg of CRDS infused i.v. over thirty minutes daily for 21 days. In each dose group, half of the patients selected were being treated with a RTI and half were on no RTI. Patients were monitored for CD4 cell levels, viral load in some cases, and safety parameters in blood. Samples of urine and semen were additionally taken for CMV by culture and for PCR assay in subsets of participants. CRDS in this 21 day study was well-tolerated and produced few reportable side effects. Systematic decreases in platelets and increases in p24 antigen previously seen with dextran sulfate were not observed in this study with CRDS. In the 21 patients testing positive for CMV at the start of the study, 12 were CMV negative at the end of 21 days. In an untreated historical control group, 0/36 went from CMV positive to negative over a period of 13-15 years. The anti-CMV activity of CRDS in this study, therefore, had a p value < 0.001, based on these historical controls. The marked temporary increases in CD4 levels seen in the single dose and the seven-day CRDS studies on HIV patients were also seen for 21 days in the current study (p = 0.0001). Treatment with CRDS seems promising against CMV in HIV infected patients, even with once daily dosing of this two-hour half-life drug. CRDS was well tolerated and its lack of toxicity makes it an attractive candidate for CMV-infected HIV patients. Multiple daily dosing, or the continuous infusion of CRDS, could lead to increased effectiveness against both HIV and CMV, especially in combination with other agents. Given the toxicity of existing anti-CMV agents, and considering the emerging importance of CMV in atherosclerotic disease, further studies on CRDS are warranted.

First Mass-resolved Measurement of High-Energy Cosmic-Ray Antiprotons.

We report new results for the cosmic-ray antiproton-to-proton ratio from 3 to 50 GeV at the top of the atmosphere. These results represent the first measurements, on an event-by-event basis, of mass-resolved antiprotons above 18 GeV. The results were obtained with the NMSU-WIZARD/CAPRICE98 balloon-borne magnet spectrometer equipped with a gas-RICH (Ring-Imaging Cerenkov) counter and a silicon-tungsten imaging calorimeter. The RICH detector was the first ever flown that is capable of identifying charge-one particles at energies above 5 GeV. The spectrometer was flown on 1998 May 28-29 from Fort Sumner, New Mexico. The measured p&d1;/p ratio is in agreement with a pure secondary interstellar production.