Commercial photodiodes and phototransistors as dosimeters of photon beams for radiotherapy.

PURPOSE: The response to radiation typically used in radiotherapy treatments has been experimentally evaluated for three samples of two phototransistors (BPW85B and OP505A) and two PIN photodiodes types (VTB8440BH and BPW34S). METHODS: To that end, a staggered irradiation cycle has been applied which included dose rate values from 0.81 to 4.87 cGy/s, achieving a total absorbed dose of 21.4 Gy. The samples have been irradiated with a linear accelerator and the relations between the induced photocurrent and the average and instantaneous dose rates, and between the accumulated charge and the absorbed dose, have been determined. The radiation-induced output currents were measured by means of an external interface of the devices to a previously designed readout unit. RESULTS: Experimental results of Si PIN photodiode BPW34S have shown a sensitivity of (13.9 ± 0.5) nC/cGy, slight sensitivity dependence on dose rate, and a high linearity of the current with the average and instantaneous dose rate, requiring only 10 V of reverse bias voltage. This device thermal drift has characterized and modeled for temperature effect compensation. CONCLUSIONS: Silicon PIN photodiode BPW34S, previously tested for X-rays and Co-60 gamma ray source, can also be a reliable candidate for dose rate and absorbed skin dose determination in typical radiotherapy treatments irradiations. A low sensitivity loss below 2% up to 21.4 Gy has been measured, allowing its use as an affordable reusable skin dosimeter. Moreover, no significant difference has been observed between its response to dose-per-pulse and changing pulse repetition frequency in terms of sensitivity and dependence with dose-rate value.

Effect of psychoeducation on self-esteem and self-efficacy among college students

Authors suggest efforts are needed to further explore the usefulness and utilization of psychoeducation at the community and professional levels as applied to various settings and populations. In addition, if developed and implemented carefully, psychoeducational interventions have promising application on other life challenges across levels of the public health, social, and educational systems. This quasiexperimental three group pre-test post-test study aims to investigate the effect of psychoeducation on the self-esteem and self-efficacy of college students. A total of 105 college students (35 subjects per group) who were enrolled at Saint Louis University, Baguio City, Philippines were included as sample. Sampling technique was purposive. The Rosenberg's Self-esteem Scale and Schwarzer's General Selfefficacy Scale were used as data gathering tools. A self-made psychoeducational module that was validated by experts in mental health and psychiatric nursing was utilized as intervention. SPSS version 20 was used for the statistical analysis. The results on the post-test scores of both treatment arms (informational and comprehensive model) were significantly higher compared to control group after eight sessions of psychoeducation. The researchers therefore conclude that both psychoeducation models (informational and comprehensive) showed evidence of effectiveness in increasing the self-esteem and self-efficacy levels of college students. 

Erratum: Child health promotion program in South Korea in collaboration with US National Aeronautics and Space Administration: Improvement in dietary and nutrition knowledge of young children

The paper was printed with an error in the order of the authors.

Child health promotion program in South Korea in collaboration with US National Aeronautics and Space Administration: Improvement in dietary and nutrition knowledge of young children

BACKGROUND/OBJECTIVES: Childhood obesity has become a global epidemic. Development of effective and sustainable programs to promote healthy behaviors from a young age is important. This study developed and tested an intervention program designed to promote healthy eating and physical activity among young children in South Korea by adaptation of the US National Aeronautics and Space Administration (NASA) Mission X (MX) Program. SUBJECTS/METHODS: The intervention program consisted of 4 weeks of fitness and 2 weeks of nutrition education. A sample of 104 subjects completed pre- and post-surveys on the Children's Nutrition Acknowledgement Test (NAT). Parents were asked for their children's characteristics and two 24-hour dietary records, the Nutrition Quotient (NQ) at baseline and a 6-week follow-up. Child weight status was assessed using Korean body mass index (BMI) percentiles. RESULTS: At baseline, 16.4% (boy: 15.4%; girl: 19.2%) of subjects were overweight or obese (based on BMI≥85%tile). Fat consumption significantly decreased in normal BMI children (48.6 ± 16.8 g at baseline to 41.9 ± 18.1 g after intervention, P < 0.05); total NQ score significantly increased from 66.4 to 67.9 (P < 0.05); total NAT score significantly improved in normal BMI children (74.3 at baseline to 81.9 after the program), children being underweight (from 71.0 to 77.0), and overweight children (77.1 at baseline vs. 88.2 after intervention, P < 0.001). CONCLUSIONS: The 6-week South Korean NASA MX project is feasible and shows favorable changes in eating behaviors and nutritional knowledge among young children.

Elastogenesis at the onset of human cardiac valve development.

Semilunar valve leaflets have a well-described trilaminar histoarchitecture, with a sophisticated elastic fiber network. It was previously proposed that elastin-containing fibers play a subordinate role in early human cardiac valve development; however, this assumption was based on data obtained from mouse models and human second and third trimester tissues. Here, we systematically analyzed tissues from human fetal first (4-12 weeks) and second (13-18 weeks) trimester, adolescent (14-19 years) and adult (50-55 years) hearts to monitor the temporal and spatial distribution of elastic fibers, focusing on semilunar valves. Global expression analyses revealed that the transcription of genes essential for elastic fiber formation starts early within the first trimester. These data were confirmed by quantitative PCR and immunohistochemistry employing antibodies that recognize fibronectin, fibrillin 1, 2 and 3, EMILIN1 and fibulin 4 and 5, which were all expressed at the onset of cardiac cushion formation (~week 4 of development). Tropoelastin/elastin protein expression was first detectable in leaflets of 7-week hearts. We revealed that immature elastic fibers are organized in early human cardiovascular development and that mature elastin-containing fibers first evolve in semilunar valves when blood pressure and heartbeat accelerate. Our findings provide a conceptual framework with the potential to offer novel insights into human cardiac valve development and disease.

Thermo-mechanical stability and strength of peptide nanostructures from molecular dynamics: self-assembled cyclic peptide nanotubes.

Peptide nanostructures present a wide range of opportunities for applications in biomedicine and bionanotechnology; hence experimental and theoretical studies aiming at determination of thermo-mechanical stability of peptide-based nanostructures are critical for the design and development of their technological applications. Here, we present a homogeneous deformation method combined with the finite elasticity theory and molecular dynamics simulations (MD) for the calculation of second-order anisotropic elastic constants for a membrane model made up of self-assembled cyclic peptide nanotubes. We have computed the values of all anisotropic elastic constants at 300 K. The value of the engineering Young's modulus (in the z direction) is 19.6 GPa. We observed a yield behavior in the z direction for a strain value of 6%. Furthermore, we also report calculated heat capacity, thermal expansion coefficient and isothermal compressibility of the system under study.

Conocimientos sobre VIH/sida en un grupo de embarazadas VIH(+)

OBJETIVO: Determinar el grado de conocimiento sobre VIH/SIDA en mujeres embarazadas VIH(+). MATERIALES Y MÉTODOS: El universo estuvo constituido por 58 embarazadas VIH(+) que acudieron a diferentes servicios de obstetricia de hospitales en Caracas durante los años 2003-2005. Se le aplicó una encuesta anónima individual, previo consentimiento asistido de las evaluadas. RESULTADOS: Fundamentalmente no existe un adecuado conocimiento sobre las vías de transmisión de la enfermedad, así como percepción del riesgo ante el VIH. CONCLUSIÓN: La promoción y planificación de la información sobre el VIH/SIDA podría contribuir en la prevención de la infección en la embarazada VIH(+).

OBJECTIVE: To describe the grade of knowledge that HIV pregnant women have about HIV/AIDS and their perception of risk of HIV infection. MATERIALS AND METHODS: Transversal descriptive study in risk women in the Gran Caracas’ hospitals during 2003-2005. They answered an individual, anonym survey with their previous assisted consent. RESULTS: There is not an adequate knowledge about the disease transmission ways. CONCLUSION: The promotion and planning of appropriate information is the key to prevent in HIV pregnant women.