Application of dynamical systems theory to the high angle of attack dynamics of the F-14

Dynamical systems theory has been used to study the nonlinear dynamics of the F-14. An eight degree of freedom model that does not include the control system present in operational F-14's has been analyzed. The aerodynamic model, supplied by NASA, includes nonlinearities as functions of the angles of attack and sideslip, the rotation rate, and the elevator deflection. A continuation method has been used to calculate the steady states of the F-14 as continuous functions of the control surface deflections. Bifurcations of these steady states have been used to predict the onset of wing rock, spiral divergence, and jump phenomena which cause the aircraft to enter a spin. A simple feedback control system was designed to eliminate the wing rock and spiral divergence instabilities. The predictions were verified with numerical simulations

Effect of sample dimensions on observed photoluminescence from Er³⁺ ions in GeGaS and LaGaS glass hosts

The 4I9/2 - 4I13/2 emission band of trivalent Er3+ is potentially interesting light source for methane (CH4) detection because of its closeness to CH4 absorption band at 1.67 µm. In the present paper we report the influence of glass sample geometry on the shape of spectra and relative emission intensity of 4I9/2 - 4I13/2 band as well as three main 4I13/2 - 4I15/2 , 4I11/2 - 4I15/2 and 4I9/2 - 4I15/2 emission bands in sulfide glasses (GeGaS and LaGaS) doped with 0.5 at.% of Er. We show that the increase of sample size leads to a significant broadening of emission spectra as well as to the substantial suppression of 4I13/2 - 4I15/2 and 4I11/2 - 4I15/2 bands. The observed effects are explained by excitation diffusion or photon trapping (consecutive absorption and emission of light by Er3+ ions [1,2]) which turns out to be more effective in large samples. We present the results of Monte-Carlo simulations supporting our considerations and we discuss the possibility of increasing the 4I9/2 - 4I13/2 emission by controlling photon trapping

The British documentary photograph as a medium of information and propaganda during the Second World War 1939 - 1945

The use of the documentary photograph as a means of recording war and human conflict is widely accepted, yet rarely analysed in terms of the evidence such images claim to portray. Existing studies have been directed towards the photograph as an end in itself, rather than as a means to an end in a broader context. This Thesis will trace the development of the documentary movement in outline, expanding in depth when referring to the British involvement within the tradition during the Second World War. The centrality of the Thesis will rest upon the need to discern between the actuality photograph as evidence when framed or presented within persuasive and propaganda terms, and the record photograph which informs and illustrates by factual content alone. Parallel to this study will be an analysis of the control and censorship process by which photography was disseminated within the media of the period when employed as an instrument reflecting governmental concerns in matters of national morale and the maintenance of social cohesion. Such official considerations have affected the contemporary use of photographs, which in retrospect have created discrepancies and anomalies in our appreciation of chronological sequences of events and military enterprises. Furthermore, such propaganda constraints have been instrumental in the creation of personas - and the myths that often surround them - both in terms of context and historical perspective. A methodology will be offered by which these tensions of control and censorship allied to the documentary tradition may be demystified, so that both the propaganda and record photograph can be assessed not only in their original contemporary context, but as sources of historical data and information

KC-135 aero-optical turbulent boundary layer/shear layer experiment revisited

The aero-optical effects associated with propagating a laser beam through both an aircraft turbulent boundary layer and artificially generated shear layers are examined. The data present comparisons from observed optical performance with those inferred from aerodynamic measurements of unsteady density and correlation lengths within the same random flow fields. Using optical instrumentation with tens of microsecond temporal resolution through a finite aperture, optical performance degradation was determined and contrasted with the infinite aperture time averaged aerodynamic measurement. In addition, the optical data were artificially clipped to compare to theoretical scaling calculations. Optical instrumentation consisted of a custom Q switched Nd:Yag double pulsed laser, and a holographic camera which recorded the random flow field in a double pass, double pulse mode. Aerodynamic parameters were measured using hot film anemometer probes and a five hole pressure probe. Each technique is described with its associated theoretical basis for comparison. The effects of finite aperture and spatial and temporal frequencies of the random flow are considered

Mothering at a distance and disclosure of maternal HIV to children in Kingston, Jamaica

Accepted for publication in a forthcoming issue of Population Horizons, an open access peer-reviewed journal by The Oxford Institute of Population Ageing.Existing guidelines (WHO, 2011) advise caretakers and professionals to disclose children’s and their caretakers’ HIV status to children, despite a lack of evidence concerning the potential implications in resource-constrained settings. Our research uses feminist Interpretative Phenomenological Analysis (IPA) to explore the experiences of HIV positive mothers in Kingston, Jamaica, focusing on their lived experiences of talking to their children about maternal HIV. This paper will focus on the concept of mothering at a distance and how this presents additional challenges for HIV positive mothers who are trying to establish emotional closeness in relation to talking to their children about their HIV. Using Hochschild’s concept of emotion work and examples from the interviews, we highlight the difficult contexts informing women’s decisions when negotiating discussions about their HIV. Women may choose full, partial or differential disclosure or children may be told their mother’s HIV status by others. Disclosure policy, we argue, reflects Anglo-Northern constructions of the family and parenting which may not adequately reflect the experiences of poor urban mothers in low and middle income countries. We argue that policy needs to recognise culturally-specific family formations, which, in Jamaica includes absent fathers, mothering at a distance and mothering non-biological children. This article reflects on the experiences of an under-researched group, poor urban Jamaican women practising mothering at a distance, using a novel methodological approach (IPA) to bring into relief unique insights into their lived experiences and will contribute to the global policy and research literature on HIV disclosure. Keywords: Feminist IPA, HIV disclosure, mothering, emotion workPeer reviewedFinal Accepted Versio

Sequence-Based Mapping and Genome Editing Reveal Mutations in Stickleback Hps5 Cause Oculocutaneous Albinism and the casper Phenotype.

Here, we present and characterize the spontaneous X-linked recessive mutation casper, which causes oculocutaneous albinism in threespine sticklebacks (Gasterosteus aculeatus). In humans, Hermansky-Pudlak syndrome results in pigmentation defects due to disrupted formation of the melanin-containing lysosomal-related organelle (LRO), the melanosome. casper mutants display not only reduced pigmentation of melanosomes in melanophores, but also reductions in the iridescent silver color from iridophores, while the yellow pigmentation from xanthophores appears unaffected. We mapped casper using high-throughput sequencing of genomic DNA from bulked casper mutants to a region of the stickleback X chromosome (chromosome 19) near the stickleback ortholog of Hermansky-Pudlak syndrome 5 (Hps5). casper mutants have an insertion of a single nucleotide in the sixth exon of Hps5, predicted to generate an early frameshift. Genome editing using CRISPR/Cas9 induced lesions in Hps5 and phenocopied the casper mutation. Injecting single or paired Hps5 guide RNAs revealed higher incidences of genomic deletions from paired guide RNAs compared to single gRNAs. Stickleback Hps5 provides a genetic system where a hemizygous locus in XY males and a diploid locus in XX females can be used to generate an easily scored visible phenotype, facilitating quantitative studies of different genome editing approaches. Lastly, we show the ability to better visualize patterns of fluorescent transgenic reporters in Hps5 mutant fish. Thus, Hps5 mutations present an opportunity to study pigmented LROs in the emerging stickleback model system, as well as a tool to aid in assaying genome editing and visualizing enhancer activity in transgenic fish

How Parents Use Time and Money

[Excerpt] This article examines weekday resource allocation decisions of married couples with a husband employed full time and with children under 18. These decisions relate, among other things, to working for pay; doing unpaid household work; purchasing services such as childcare, laundry and drycleaning, and food away from home; and eating out. Information about spending decisions was obtained from the 2009 Consumer Expenditure Survey (CE) and information about time use was obtained from the 2009 American Time Use Survey (ATUS). Results show that, Regardless of employment status, wives were more likely than husbands to spend time in household activities. On an average weekday, married fathers spent more time working than married mothers did, even married mothers employed full time. The proportion of families reporting childcare expenses and the average amount spent by those reporting were highest for families with full-time working wives and lowest for families with wives not employed for pay. Consistent with other research, working-wife families did not spend more on housekeeping and laundry services than did families with wives not employed for pay. Families with full-time working wives spent the greatest dollar amount on food away from home, but there was no significant difference in spending between families with part-time working wives and families with wives not employed for pay