Novel dual single sided silicon strip detector chip for radiotherapy verification

A novel dual single sided silicon strip detector (SSSSD) chip was designed to meet clinical requirements in radiotherapy verification. An available design from Micron Semiconductor Ltd. (BB7, 500 µ m thick) was the base of a two-dimensional detector adapted into a special configuration with the aim of uniforming and minimizing foreing materials around the active area (64 × 64 mm2). With this purpose, two independent BB7 SSSSDs were mounted in a perpendicular configuration, separated by a 500 µ m kapton dielectric film with the same dimensions as the silicon wafers, thus minimizing air gaps in between. This new configuration, called the dual SSSSD chip design, was mounted on kapton printed circuit board (PCB). Both silicon wafers were divided into 32 strips, 2 mm width each. The aim of developing this detector was to allow 2D dose measurements, improve spatial resolution and perform radiotherapy treatment verification faster than with a previous prototype. Characteristics and performance of the novel detector are presented

HIV-exposed infants with acute respiratory failure secondary to acute lower respiratory infections managed with and without mechanical ventilation

Objectives. The decision to provide mechanical ventilation (intermittent positive pressure ventilation (IPPV)) to HIV-exposed infants in resource-poor settings has remained difficult owing to problems in confirming HIV infection and the lack of data on outcome. We evaluated the predictive value of the HIV antibody test in confirming infection in infants requiring mechanical ventilation for acute lower respiratory infections (ALRis), and compared the outcome for children denied access with the outcome for similar subjects who were ventilated.Setting and design. This investigative study was conducted over a 12-month period at the paediatric intensive care unit (PICU) at King Edward VIII Hospital (KEH) in Durban, and at Ngwelezana Hospital in northern KwaZulu-Natal.Subjects. HIV-exposed patients with acute respiratory failure (ARF) secondary to ALRI entering the PICU at KEH were enrolled into the IPPV arm, while similar children who were refused such care at Ngwelezana Hospital were admitted into the non-IPPV arm. Standardised protocols for entry and management of enrolled subjects were utilised.Outcome measures. HIV DNA polymerase chain reaction (PCR) testing was performed to establish HIV status. Clinical and laboratory parameters were correlated with HIV status to determine predictors of infection and outcome (survival to discharge).Results. One hundred and sixteen HIV-exposed infants were enrolled, 49 into the IPPV arm and 67 into the non-IPPV arm. The median age of both groups was 3.0 months (0.5 - 11 months), and the male/female ratio and proportion of infants under 3 months of age were similar in both groups. The predictive values of the HIV antibody test in determining HIV infection in the IPPV and non-IPPV arms were 87.8% and 85.0% respectively. Splenomegaly and a serum globulin of >35 g/l increased the likelihood of being HIV PCR- positive (p = 0.006 and p = 0.04 respectively). Survival to discharge rates for HIV-infected children in the IPPV and non-IPPV arms were 41.9% and 24.6% respectively (p = 0.08). Age less than 3 months (p = 0.04) and very severe pneumonia (p = 0.007) were the only indicators of poor outcome.Conclusion. Mechanical ventilation provided little benefit in HIV-infected children with ARF from ALRI. An HIV antibody test in infants with ALRI and ARF is highly suggestive of HIV infection. Splenomegaly and a serumglobulin of greater than 35 g/l were the only useful markers in identifying HIV infection

Semiclassical Inequivalence of Polygonalized Billiards

Polygonalization of any smooth billiard boundary can be carried out in several ways. We show here that the semiclassical description depends on the polygonalization process and the results can be inequivalent. We also establish that generalized tangent-polygons are closest to the corresponding smooth billiard and for de Broglie wavelengths larger than the average length of the edges, the two are semiclassically equivalent.Comment: revtex, 4 ps figure

Classical and quantum decay of one dimensional finite wells with oscillating walls

To study the time decay laws (tdl) of quasibounded hamiltonian systems we have considered two finite potential wells with oscillating walls filled by non interacting particles. We show that the tdl can be qualitatively different for different movement of the oscillating wall at classical level according to the characteristic of trapped periodic orbits. However, the quantum dynamics do not show such differences.Comment: RevTeX, 15 pages, 14 PostScript figures, submitted to Phys. Rev.

Descripción de tres protocolos anestésicos fijos en cerdas sometidas a trasferencia embrionaria quirúrgica

La utilización del cerdo como modelo en investigación biomédica ha dado lugar a múltiples descripciones de protocolos anestésicos. El presente trabajo tiene por objeto socializar las dosis y drogas utilizadas en tres protocolos. Las tres cerdas anestesiadas, una por protocolo, son parte de la puesta a punto de la técnica de transferencia embrionaria quirúrgica. Protocolo 1: Medicación preanestésica: ketamina 15 mg/kg vía intramuscular, xilacina 3 mg/kg intramuscular. Inducción: midazolam 0,15 mg/kg vía EV. Mantenimiento: xilacina 0,6 mg/kg EV, y ketamina 3 mg/kg EV + dos refuerzos de ketamina 2 mg/kg EV. Protocolo 2: Medicación preanestésica: ketamina 15 mg/kg vía intramuscular, xilacina 3 mg/kg intramuscular. Inducción: midazolam 0,14 mg/kg vía endovenosa. Mantenimiento por vía endovenosa: Ketamina 1,5 mg/kg, Xilacina 0,6 mg/kg, Ketamina 2 mg/kg. Protocolo 3: Medicación preanestésica: ketamina 15 mg/kg vía intramuscular, xilacina 3 mg/kg intramuscular. Inducción: ketamina 5 mg/kg vía endovenosa. Mantenimiento por vía endovenosa: Xilacina 0,6 mg/kg, Ketamina 3 mg/kg, Ketamina 2 mg/kg, Ketamina 2 mg/kg. El planteo farmacológico del protocolo 3 requirió mayor frecuencia y dosis de drogas utilizada

Lipase mediated enzymatic kinetic resolution of phenylethyl halohydrins acetates: A case of study and rationalization

Racemic phenylethyl halohydrins acetates containing several groups attached to the aromatic ring were resolved via hydrolysis reaction in the presence of lipase B from Candida antarctica (Novozym\uae 435). In all cases, the kinetic resolution was highly selective (E > 200) leading to the corresponding (S)-\u3b2-halohydrin with ee > 99 %. However, the time required for an ideal 50 % conversion ranged from 15 min for 2,4-dichlorophenyl chlorohydrin acetate to 216 h for 2-chlorophenyl bromohydrin acetate. Six chlorohydrins and five bromohydrins were evaluated, the latter being less reactive. For the \u3b2-brominated substrates, steric hindrance on the aromatic ring played a crucial role, which was not observed for the \u3b2-chlorinated derivatives. To shed light on the different reaction rates, docking studies were carried out with all the substrates using MD simulations. The computational data obtained for the \u3b2-brominated substrates, based on the parameters analysed such as NAC (near attack conformation), distance between Ser-O and carbonyl-C and oxyanion site stabilization were in agreement with the experimental results. On the other hand, the data obtained for \u3b2-chlorinated substrates suggested that physical aspects such as high hydrophobicity or induced change in the conformation of the enzymatic active site are more relevant aspects when compared to steric hindrance effects

Melting of a colloidal crystal

A melting transition for a system of hard spheres interacting by a repulsive Yukawa potential of DLVO form is studied. To find the location of the phase boundary, we propose a simple theory to calculate the free energies for the coexisting liquid and solid. The free energy for the liquid phase is approximated by a virial expansion. The free energy of the crystalline phase is calculated in the spirit of the Lenard-Jonnes and Devonshire (LJD) theory. The phase boundary is found by equating the pressures and chemical potentials of the coexisting phases. When the approximation leading to the equation of state for the liquid breakes down, the first order transition line is also obtained by applying the Lindemann criterion to the solid phase. Our results are then compared with the Monte Carlo simulations.Comment: 7 pages, Revtex (using twocolumn style), four figures and postscript file. Submitted to Physica

Radia2: A New Tool for Radiotherapy Verification

Radiotherapy is nowadays a proven technique in cancer treatments. Within the evolution of radiotherapy treatments towards more complex techniques, the need of new dosimetric methods for treatment verifications has appeared. In order to reach an improved dosimetric method, a collaboration was started to transfer knowledge from nuclear reaction instrumentation to medical applications, involving several departments from the University of Seville, Centro Nacional de Aceleradores (CNA), the Hospital Universitario Virgen Macarena and the company Inabensa. The first prototype, patent pending [2], gave very promising results. Currently, a critical review is being carried out to create an improved system

Genome-Wide Linkage Scan of Bipolar Disorder in a Colombian Population Isolate Replicates Loci on Chromosomes 7p21–22, 1p31, 16p12 and 21q21–22 and Identifies a Novel Locus on Chromosome 12q

Background/Aims: Bipolar disorder (BP) is a severe psychiatric illness, characterised by alternating episodes of depression and mania, which ranks among the top ten causes of morbidity and life-long disability world-wide. We have previously performed a whole-genome linkage scan on 6 pedigrees segregating severe BP from the well-characterised population isolate of Antioquia, Colombia. We recently collected genotypes for the same set of 382 autosomal microsatellite markers in 9 additional Antioquian BP pedigrees. Here, we report the analysis of the combined pedigree set