The birth of airplane stability theory

Airplane stability theory was born at the end of the XIX century and matured around 100 years ago, when airplanes were hardly controllable yet. The success and safety of flights in the pioneer years depended upon largely unknown stability and control characteristics. Understanding the modes of airplane motion has been of paramount importance for the development of aviation. The contributions made by a few scientists in the decades preceding and following the first flight by the Wright brothers set the concepts and equations that, with minor notation aspects, have remained almost unchanged till present day.Magraner Rullan, JP.; Martinez-Val, R. (2014). The birth of airplane stability theory. Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering. 228(9):1498-1506. doi:10.1177/0954410013494139S149815062289PERKINS, C. D. (1970). Development of airplane stability and control technology /1970 Von Karman Lecture/. Journal of Aircraft, 7(4), 290-301. doi:10.2514/3.44167Abzug, M. J., & Larrabee, E. E. (2002). Airplane Stability and Control, Second Edition. doi:10.1017/cbo9780511607141Graham, W. R. (1999). Asymptotic analysis of the classical aircraft stability equations. The Aeronautical Journal, 103(1020), 95-103. doi:10.1017/s0001924000027792Bryan, G. H., & Williams, W. E. (1904). The Longitudinal Stability of Aerial Gliders. Proceedings of the Royal Society of London, 73(488-496), 100-116. doi:10.1098/rspl.1904.0017Wegener, P. P. (1997). What Makes Airplanes Fly? doi:10.1007/978-1-4612-2254-5Pradeep, S., & Kamesh, S. (1999). Does the Phugoid Frequency Depend on Speed? Journal of Guidance, Control, and Dynamics, 22(2), 372-373. doi:10.2514/2.4391Phillips, W. F. (2000). Phugoid Approximation for Conventional Airplanes. Journal of Aircraft, 37(1), 30-36. doi:10.2514/2.2586Pamadi, B. N. (2004). Performance, Stability, Dynamics, and Control of Airplanes, Second Edition. doi:10.2514/4.862274Ananthkrishnan, N., & Ramadevi, P. (2002). Consistent Approximations to Aircraft Longitudinal Modes. Journal of Guidance, Control, and Dynamics, 25(4), 820-824. doi:10.2514/2.4952McRuer, D. T., Graham, D., & Ashkenas, I. (1990). Aircraft Dynamics and Automatic Control. doi:10.1515/978140085598

Classical skyrmions in SU(N)/SO(N) cosets

We construct the skyrmion solutions appearing in the coset spaces SU(N)/SO(N) for N > 2 and compute their classical mass. For N = 3, the third homotopy group pi_3(SU(3)/SO(3)) = Z_4 implies the existence of two distinct solutions: the skyrmion of winding number two has spherical symmetry and is found to be the lightest non-trivial field configuration; the skyrmion and antiskyrmion of winding number plus and minus one are slightly heavier and of toroidal shape. For N >= 4, there is only one skyrmion since the third homotopy group is Z_2. It is found to have spherical symmetry and is significantly lighter than the N = 3 solutions.Comment: 14 pages, 3 figures; v2: discussion improve

Epidemiology of Subpatent Plasmodium Falciparum Infection: Implications for Detection of Hotspots with Imperfect Diagnostics.

At the local level, malaria transmission clusters in hotspots, which may be a group of households that experience higher than average exposure to infectious mosquitoes. Active case detection often relying on rapid diagnostic tests for mass screen and treat campaigns has been proposed as a method to detect and treat individuals in hotspots. Data from a cross-sectional survey conducted in north-western Tanzania were used to examine the spatial distribution of Plasmodium falciparum and the relationship between household exposure and parasite density. Dried blood spots were collected from consenting individuals from four villages during a survey conducted in 2010. These were analysed by PCR for the presence of P. falciparum, with the parasite density of positive samples being estimated by quantitative PCR. Household exposure was estimated using the distance-weighted PCR prevalence of infection. Parasite density simulations were used to estimate the proportion of infections that would be treated using a screen and treat approach with rapid diagnostic tests (RDT) compared to targeted mass drug administration (tMDA) and Mass Drug Administration (MDA). Polymerase chain reaction PCR analysis revealed that of the 3,057 blood samples analysed, 1,078 were positive. Mean distance-weighted PCR prevalence per household was 34.5%. Parasite density was negatively associated with transmission intensity with the odds of an infection being subpatent increasing with household exposure (OR 1.09 per 1% increase in exposure). Parasite density was also related to age, being highest in children five to ten years old and lowest in those > 40 years. Simulations of different tMDA strategies showed that treating all individuals in households where RDT prevalence was above 20% increased the number of infections that would have been treated from 43 to 55%. However, even with this strategy, 45% of infections remained untreated. The negative relationship between household exposure and parasite density suggests that DNA-based detection of parasites is needed to provide adequate sensitivity in hotspots. Targeting MDA only to households with RDT-positive individuals may allow a larger fraction of infections to be treated. These results suggest that community-wide MDA, instead of screen and treat strategies, may be needed to successfully treat the asymptomatic, subpatent parasite reservoir and reduce transmission in similar settings

Leaving the Past (Self) Behind: Non-Reporting Rape Survivors' Narratives of Self and Action

Using a symbolic interactionist framework, this study considers the narratives of non-reporting rape survivors. We use interviews to examine the complex processes that inform a survivor’s decision not to report. Rape is not interpreted as an isolated event; it is something that is seen as caused by, connected to, and affecting the survivor’s sense of self and agency. Rape forces the survivor to reconstruct a sense of agency in the aftermath of the traumatic attack. Rather than report the rape, the survivors constructed narratives that direct blame and accountability toward the “old self”. This less visible, yet still agentic strategy, allows the survivors to regain a sense of agency and control. As a result, a more positive, optimistic self can be constructed, while pursuing legal justice would force them to reenact an “old” self that cannot be disentangled from the rape

Pedestrian, Crowd, and Evacuation Dynamics

This contribution describes efforts to model the behavior of individual pedestrians and their interactions in crowds, which generate certain kinds of self-organized patterns of motion. Moreover, this article focusses on the dynamics of crowds in panic or evacuation situations, methods to optimize building designs for egress, and factors potentially causing the breakdown of orderly motion.Comment: This is a review paper. For related work see http://www.soms.ethz.c

Health-related quality of life following a clinical weight loss intervention among overweight and obese adults: intervention and 24 month follow-up effects

BACKGROUND: Despite a growing literature on the efficacy of behavioral weight loss interventions, we still know relatively little about the long terms effects they have on HRQL. Therefore, we conducted a study to investigate the immediate post-intervention (6 months) and long-term (12 and 24 months) effects of clinically based weight management programs on HRQL. METHODS: We conducted a randomized clinical trial in which all participants completed a 6 month clinical weight loss program and were randomized into two 6-month extended care groups. Participants then returned at 12 and 24 months for follow-up assessments. A total of 144 individuals (78% women, M age = 50.2 (9.2) yrs, M BMI = 32.5 (3.8) kg/m(2)) completed the 6 month intervention and 104 returned at 24 months. Primary outcomes of weight and HRQL using the SF-36 were analyzed using multivariate repeated measures analyses. RESULTS: There was complete data on 91 participants through the 24 months of the study. At baseline the participants scored lower than U.S. age-specific population norms for bodily pain, vitality, and mental health. At the completion of the 6 month clinical intervention there were increases in the physical and mental composite measures as well as physical functioning, general health, vitality, and mental health subscales of the SF-36. Despite some weight regain, the improvements in the mental composite scale as well as the physical functioning, vitality, and mental health subscales were maintained at 24 months. There were no significant main effects or interactions by extended care treatment group or weight loss group (whether or not they maintained 5% loss at 24 months). CONCLUSION: A clinical weight management program focused on behavior change was successful in improving several factors of HRQL at the completion of the program and many of those improvements were maintained at 24 months. Maintaining a significant weight loss (> 5%) was not necessary to have and maintain improvements in HRQL

Meteorological Controls on Local and Regional Volcanic Ash Dispersal

Volcanic ash has the capacity to impact human health, livestock, crops and infrastructure, including international air traffic. For recent major eruptions, information on the volcanic ash plume has been combined with relatively coarse-resolution meteorological model output to provide simulations of regional ash dispersal, with reasonable success on the scale of hundreds of kilometres. However, to predict and mitigate these impacts locally, significant improvements in modelling capability are required. Here, we present results from a dynamic meteorological-ash-dispersion model configured with sufficient resolution to represent local topographic and convectively-forced flows. We focus on an archetypal volcanic setting, Soufrière, St Vincent, and use the exceptional historical records of the 1902 and 1979 eruptions to challenge our simulations. We find that the evolution and characteristics of ash deposition on St Vincent and nearby islands can be accurately simulated when the wind shear associated with the trade wind inversion and topographically-forced flows are represented. The wind shear plays a primary role and topographic flows a secondary role on ash distribution on local to regional scales. We propose a new explanation for the downwind ash deposition maxima, commonly observed in volcanic eruptions, as resulting from the detailed forcing of mesoscale meteorology on the ash plume

Inducible Costimulator Expression Regulates the Magnitude of Th2-Mediated Airway Inflammation by Regulating the Number of Th2 Cells

Inducible Costimulator (ICOS) is an important regulator of Th2 lymphocyte function and a potential immunotherapeutic target for allergy and asthma. A SNP in the ICOS 5' promoter in humans is associated with increased atopy and serum IgE in a founder population and increased ICOS surface expression and Th2 cytokine production from peripheral blood mononuclear cells. However, it is unknown if increased ICOS expression contributes to disease progression or is a result of disease pathology.We developed a mouse model in which ICOS surface expression levels are genetically predetermined to test our hypothesis that genetic regulation of ICOS expression controls the severity of Th2 responses in vivo. Using ICOS+/+ and ICOS+/- mice in a Th2 model of airway inflammation, we found that T cells from the ICOS+/- mice had reduced ICOS expression and decreased Th2-mediated inflammation in vivo. Although the activation status of the T cells did not differ, T cells isolated from the lungs and draining lymph nodes of ICOS+/- mice at the peak of inflammation produced less Th2 cytokines upon stimulation ex vivo. Using 4get mice, which express GFP upon IL-4 transcription, we determined that the decreased Th2 cytokines in ICOS+/- is due to reduced percentage of Th2 cells and not a defect in their ability to produce IL-4.These data suggest that in both mice and humans, the level of ICOS surface expression regulates the magnitude of the in vivo Th2 response, perhaps by influencing Th2 differentiation

Androgen receptor expresion in breast cancer: Relationship with clinicopathological characteristics of the tumors, prognosis, and expression of metalloproteases and their inhibitors

<p>Abstract</p> <p>Background</p> <p>In the present study we analyze, in patients with breast cancer, the tumor expression of androgen receptors (AR), its relationship with clinicopathological characteristics and with the expression of several matrix metalloproteases (MMPs) and their inhibitors (TIMPs), as well as with prognosis.</p> <p>Methods</p> <p>An immunohistochemical study was performed using tissue microarrays and specific antibodies against AR, MMPs -1, -2, -7, -9, -11, -13, -14, and TIMPs -1, -2 and -3. More than 2,800 determinations on tumor specimens from 111 patients with primary invasive ductal carcinoma of the breast (52 with axillary lymph node metastases and 59 without them) and controls were performed. Staining results were categorized using a score based on the intensity of the staining and a specific software program calculated the percentage of immunostained cells automatically.</p> <p>Results</p> <p>A total of 83 cases (74.8%) showed a positive immunostaining for AR, but with a wide variation in the staining score values. There were no significant associations between the total immunostaining scores for AR and any clinicopathological parameters. However, score values for MMP-1, -7 and -13, were significantly higher in AR-positive tumors than in AR-negative tumors. Likewise, when we considered the cellular type expressing each factor, we found that AR-positive tumors had a higher percentage of cases positive for MMP-1, -7, -11, and TIMP-2 in their malignant cells, as well as for MMP-1 in intratumoral fibroblasts. On the other hand, multivariate analysis demonstrated that patients with AR-positive tumors have a significant longer overall survival than those with AR-negative breast carcinomas (<it>p </it>= 0.03).</p> <p>Conclusion</p> <p>Our results confirm that AR are commonly expressed in breast cancer, and are correlated with the expression of some MMPs and TIMP-2. Although we found a specific value of AR expression to be a prognostic indicator in breast cancer, the functional role of AR in these neoplasms is still unclear and further data are needed in order to clarify their biological signification in breast cancer.</p

PhiSiGns: an online tool to identify signature genes in phages and design PCR primers for examining phage diversity

<p>Abstract</p> <p>Background</p> <p>Phages (viruses that infect bacteria) have gained significant attention because of their abundance, diversity and important ecological roles. However, the lack of a universal gene shared by all phages presents a challenge for phage identification and characterization, especially in environmental samples where it is difficult to culture phage-host systems. Homologous conserved genes (or "signature genes") present in groups of closely-related phages can be used to explore phage diversity and define evolutionary relationships amongst these phages. Bioinformatic approaches are needed to identify candidate signature genes and design PCR primers to amplify those genes from environmental samples; however, there is currently no existing computational tool that biologists can use for this purpose.</p> <p>Results</p> <p>Here we present PhiSiGns, a web-based and standalone application that performs a pairwise comparison of each gene present in user-selected phage genomes, identifies signature genes, generates alignments of these genes, and designs potential PCR primer pairs. PhiSiGns is available at (<url>http://www.phantome.org/phisigns/</url>; <url>http://phisigns.sourceforge.net/</url>) with a link to the source code. Here we describe the specifications of PhiSiGns and demonstrate its application with a case study.</p> <p>Conclusions</p> <p>PhiSiGns provides phage biologists with a user-friendly tool to identify signature genes and design PCR primers to amplify related genes from uncultured phages in environmental samples. This bioinformatics tool will facilitate the development of novel signature genes for use as molecular markers in studies of phage diversity, phylogeny, and evolution.</p