Spacecraft induced error sources

The attitude control and measurement systems aboard the LANDSAT 2 and D satellites are described and associated errors are discussed. Also, the ephemeris errors from various tracking systems are examined. Use of the Global Positioning System and improved attitude control instruments is expected to greatly reduce the errors in LANDSAT D in comparison with previous LANDSATS

The Isospin Distribution of Fragments in Reactions 96Ru+96Ru, 96Ru+96Zr, 96Zr+96Ru, and 96Zr+96Zr at Beam Energy 400 AMeV

The isospin distribution of particles and fragments in collisions 96Ru+96Ru, 96Ru+96Zr, 96Zr+96Ru, and 96Zr+96Zr at beam energy 400 AMeV is studied with isospin dependent QMD model. We find that the rapidity distribution of differential neutron-proton counting in neutron rich nucleus-nucleus collisions at intermediate energies is sensitive to the isospin dependent part of nuclear potential. The study of the N/Z ratio of nucleons, light charged particles (LCP) and intermediate mass fragments (IMF) shows that the isospin dependent part of nuclear potential drives IMF to be more isospin symmetric and emitted nucleons to be more neutron rich. From the study of the time evolution of the isospin distribution in emitted nucleons, LCP and IMF we find that neutrons diffuse much faster than protons at beginning and the final isospin distribution is a result of dynamical balance of symmetry potential and Coulomb force under the charge conservation.Comment: 10 pages, 5 figure

Fracturas de implantes de tibia. Consecuencias para los ensayos de los implantes

El objetivo de este trabajo es estudiar los modelos de fracturas de prótesis de tibia descritos en la literatura y, sobre la base de dichos conocimientos, desarrollar un ensayo para implantes en la cual se logren simular condiciones fisiológicas. El caso descrito con mayor frecuencia en la literatura es la migración de la parte medial de la prótesis, fenómeno que, a menudo, antecede a la fractura de la prótesis. La posición defectuosa resultante de dicha migración modifica el eje mecánico y provoca una sobrecarga en la parte medial de la prótesis. Se ha desarrollado un ensayo de implantes que simula el modelo de fallo in-vivo. Dos bases de material sintético de diferente dureza simulan la diferente densidad ósea medial y lateral, para permitir una migración del lado medial del platillo. En el ensayo dinámico el platillo tibial es sometido a una carga de un solo lado y el vástago de la prótesis se apuntala con un contrasoporte. Para simular el entorno fisiológico, todo el dispositivo se encuentra sumergido en una solución de Ringer a 37°. El implante de tibia es expuesto durante 10 millones de ciclos a una carga que corresponde al quíntuple del peso del cuerpo (4.000 N). El punto de aplicación de la fuerza fue tomado de datos de análisis del caminar (marcha en superficie plana, ascendente y descendente, subir escaleras). Con esta carga fisiológica se efectuaron los primeros ensayos. En éstas quedó demostrado que productos clínicamente exitosos podían superar el ensayo. Por el contrario, los productos con modelos de fracturas conocidos no la superaron. Los primeros resultados con estos productos demostraron también que el ensayo generaba muestras de fractura semejantes a las que se producen in vivo. Debido a la configuración fisiológica del dispositivo se somete el sistema completo es decir el platillo, el vástago de la prótesis y la unión - generalmente modular - entre ambos a ensayo. El "ensayo fisiológico de tibia " descrito ayuda a evaluar los diseños de tibia antes de que se autorice su venta. Nuevos implantes y modificaciones de diseño en implantes ya existentes son puestos a la venta después de cumplir con las exigencias del ensayo.Peer Reviewe

Bacterial protein microarrays for identification of new potential diagnostic markers for Neisseria meningitidis infections

Neisseria meningitidis is the most common cause of meningitis and causes epidemic outbreaks. One trait of N. meningitidis, which is associated with most of the currently recognized virulence determinants, is the presence of phase-variable genes that are suspected to enhance its ability to cause an invasive disease. To detect the immune responses to phase-variable expressed proteins, we applied protein microarray technology for the screening of meningitis patient sera. We amplified all 102 known phase-variable genes from N. meningitidis serogroup B strain MC58 by polymerase chain reaction and subcloned them for expression in Escherichia coli. With this approach, we were able to express and purify 67 recombinant proteins representing 66% of the annotated genes. These were spotted robotically onto coated glass slides to generate protein microarrays, which were screened using 20 sera of patients suffering from meningitis, as well as healthy controls. From these screening experiments, 47 proteins emerged as immunogenic, exhibiting a variable degree of seroreactivity with some of the patient sera. Nine proteins elicited an immune response in more than three patients, with one of them, the phase-variable opacity protein OpaV (NMB0442), showing responses in 11 patient sera. This is the first time that protein microarray technology has been applied for the investigation of genetic phase variation in pathogens. The identification of disease-specific proteins is a significant target in biomedical research, as such proteins may have medical, diagnostic, and commercial potential as disease markers

Weight Changes Post-Phentermine Use

Purpose: Evaluate weight maintenance in subjects who lost weight while taking phentermine (PTM). Methods: This study was conducted by utilizing a validated survey to collect self-reported data about weight changes post-PTM use. The survey was sent to 19,986 email addresses of current and former patients of a PTM-based outpatient clinic, located in Chicago, IL; 546 participants completed the survey. Results were analyzed using a variety of techniques. Results: At the time of the survey, 42% of responders maintained all the weight lost while on PTM, and 25.2% had maintained a weight loss of at least 10% of their body weight. The average weight lost and maintained at the time of the survey was 3.75% ± 13.8% of body weight or 8.74 lbs ± 27.45 lbs. Nineteen responders had no net weight change. Fifty-nine responders reported a net weight gain, ranging from 2 to 70 lbs with a mean net weight gain of 16.07 lbs ± 13.87 lbs. The duration of time since discontinuing PTM use had a significant correlation with weight maintenance: r = 0.340, p value = .000. There was no significant correlation between duration of time using PTM and weight maintenance. No correlations were identified between education, income, or ethnicity and weight maintenance. A correlation was identified between weight maintenance and current exercise level: r = 0.218, p value = .000. Conclusions: Although more research is needed, with the results of this study, the investigators suggest that post-PTM use, weight regain is not significantly higher than weight regain through other weight loss programs. In order to achieve long-term weight loss maintenance, it may behoove patients to receive professional guidance about behavior modifications to maintain weight lost, particularly related to exercise and dietary changes. The investigators of this study suggest greater emphasis on behavior modification in patients taking PTM is indicated

Sector coupling via hydrogen to lower the cost of energy system decarbonization

There is growing interest in hydrogen (H$_2$) use for long-duration energy storage in a future electric grid dominated by variable renewable energy (VRE) resources. Modelling the role of H$_2$ as grid-scale energy storage, often referred as "power-to-gas-to-power (P2G2P)" overlooks the cost-sharing and emission benefits from using the deployed H$_2$ production and storage assets to also supply H$_2$ for decarbonizing other end-use sectors where direct electrification may be challenged. Here, we develop a generalized modelling framework for co-optimizing energy infrastructure investment and operation across power and transportation sectors and the supply chains of electricity and H$_2$, while accounting for spatio-temporal variations in energy demand and supply. Applying this sector-coupling framework to the U.S. Northeast under a range of technology cost and carbon price scenarios, we find a greater value of power-to-H$_2$ (P2G) versus P2G2P routes. P2G provides flexible demand response, while the extra cost and efficiency penalties of P2G2P routes make the solution less attractive for grid balancing. The effects of sector-coupling are significant, boosting VRE generation by 12-55% with both increased capacities and reduced curtailments and reducing the total system cost (or levelized costs of energy) by 6-14% under 96% decarbonization scenarios. Both the cost savings and emission reductions from sector coupling increase with H$_2$ demand for other end-uses, more than doubling for a 96% decarbonization scenario as H$_2$ demand quadraples. Moreover, we found that the deployment of carbon capture and storage is more cost-effective in the H$_2$ sector because of the lower cost and higher utilization rate. These findings highlight the importance of using an integrated multi-sector energy system framework with multiple energy vectors in planning energy system decarbonization pathways.Comment: 19 pages, 7 figure

Impacted maxillary canines and root resorptions of neighbouring teeth: a radiographic analysis using cone-beam computed tomography

The study analyses the location of impacted maxillary canines and factors influencing root resorptions of adjacent teeth using cone-beam computed tomography (CBCT). In addition, the interrater reliability between observers of two different dental specialties for radiographic parameters will be evaluated. CBCT images of patients who were referred for radiographic localization of impacted maxillary canines and/or suspicion of root resorptions of adjacent teeth were included. The study analysed the exact three-dimensional location of the impacted canines in the anterior maxilla, frequency and extent of root resorptions, and potential influencing factors. To assess interrater agreement, Cohen's correlation parameters were calculated. This study comprises 113 patients with CBCT scans, and 134 impacted canines were analysed retrospectively. In the patients evaluated, 69 impacted canines were located palatally (51.49 per cent), 41 labially (30.60 per cent), and 24 (17.91 per cent) in the middle of the alveolar process. Root resorptions were found in 34 lateral incisors (25.37 per cent), 7 central incisors (5.22 per cent), 6 first premolars (4.48 per cent), and 1 second premolar (0.75 per cent). There was a significant correlation between root resorptions on adjacent teeth and localization of the impacted canine in relation to the bone, as well as vertical localization of the canine. Interrater agreement showed values of 0.546-0.877. CBCT provides accurate information about location of the impacted canine and prevalence and degree of root resorption of neighbouring teeth with high interrater correlation. This information is of great importance for surgeons and orthodontists for accurate diagnostics and interdisciplinary treatment plannin

What is the evidence for giving chemoprophylaxis to children or students attending the same preschool, school or college as a case of meningococcal disease?

We performed a systematic literature review to assess the effectiveness of chemoprophylaxis for contacts of sporadic cases of invasive meningococcal disease (IMD) in educational settings. No studies directly compared IMD risk in contacts with/without chemoprophylaxis. However, compared to the background incidence, an elevated IMD risk was identified in settings without a general recommendation for chemoprophylaxis in pre-schools [pooled risk difference (RD) 58·2/10⁵, 95% confidence interval (CI) 27·3-89·0] and primary schools (pooled RD 4·9/10⁵, 95% CI 2·9-6·9) in the ~30 days after contact with a sporadic IMD case, but not in other educational settings. Thus, limited but consistent evidence suggests the risk of IMD in pre-school contacts of sporadic IMD cases is significantly increased above the background risk, but lower than in household contacts (pooled RD for household contacts with no chemoprophylaxis vs. background incidence: 480·1/10⁵, 95% CI 321·5-639·9). We recommend chemoprophylaxis for pre-school contacts depending on an assessment of duration and closeness of contact