Rotorcraft convertible engine study

The objective of the Rotorcraft Convertible Engine Study was to define future research and technology effort required for commercial development by 1988 of convertible fan/shaft gas turbine engines for unconventional rotorcraft transports. Two rotorcraft and their respective missions were defined: a Fold Tilt Rotor aircraft and an Advancing Blade Concept (ABC) rotorcraft. Sensitivity studies were conducted with these rotorcraft to determine parametrically the influence of propulsion characteristics on aircraft size, mission fuel requirements, and direct operating costs (DOC). The two rotorcraft were flown with conventional propulsion systems (separate lift/cruise engines) and with convertible propulsion systems to determine the benefits to be derived from convertible engines. Trade-off studies were conducted to determine the optimum engine cycle and staging arrangement for a convertible engine. Advanced technology options applicable to convertible engines were studied. Research and technology programs were identified which would ensure technology readiness for commercial development of convertible engines by 1988

MM Algorithms for Geometric and Signomial Programming

This paper derives new algorithms for signomial programming, a generalization of geometric programming. The algorithms are based on a generic principle for optimization called the MM algorithm. In this setting, one can apply the geometric-arithmetic mean inequality and a supporting hyperplane inequality to create a surrogate function with parameters separated. Thus, unconstrained signomial programming reduces to a sequence of one-dimensional minimization problems. Simple examples demonstrate that the MM algorithm derived can converge to a boundary point or to one point of a continuum of minimum points. Conditions under which the minimum point is unique or occurs in the interior of parameter space are proved for geometric programming. Convergence to an interior point occurs at a linear rate. Finally, the MM framework easily accommodates equality and inequality constraints of signomial type. For the most important special case, constrained quadratic programming, the MM algorithm involves very simple updates.Comment: 16 pages, 1 figur

Electronic tuning and uniform superconductivity in CeCoIn5

We report a globally reversible effect of electronic tuning on the magnetic phase diagram in CeCoIn_{5} driven by electron (Pt and Sn) and hole (Cd, Hg) doping. Consequently, we are able to extract the superconducting pair breaking component for hole and electron dopants with pressure and co-doping studies, respectively. We find that these nominally non-magnetic dopants have a remarkably weak pair breaking effect for a d-wave superconductor. The pair breaking is weaker for hole dopants, which induce magnetic moments, than for electron dopants. Furthermore, both Pt and Sn doping have a similar effect on superconductivity despite being on different dopant sites, arguing against the notion that superconductivity lives predominantly in the CeIn_{3} planes of these materials. In addition, we shed qualitative understanding on the doping dependence with density functional theory calculations.Comment: Accepted for publication in Phys. Rev. Lett. (October 1, 2012

Dissecting a complex chemical stress: chemogenomic profiling of plant hydrolysates.

The efficient production of biofuels from cellulosic feedstocks will require the efficient fermentation of the sugars in hydrolyzed plant material. Unfortunately, plant hydrolysates also contain many compounds that inhibit microbial growth and fermentation. We used DNA-barcoded mutant libraries to identify genes that are important for hydrolysate tolerance in both Zymomonas mobilis (44 genes) and Saccharomyces cerevisiae (99 genes). Overexpression of a Z. mobilis tolerance gene of unknown function (ZMO1875) improved its specific ethanol productivity 2.4-fold in the presence of miscanthus hydrolysate. However, a mixture of 37 hydrolysate-derived inhibitors was not sufficient to explain the fitness profile of plant hydrolysate. To deconstruct the fitness profile of hydrolysate, we profiled the 37 inhibitors against a library of Z. mobilis mutants and we modeled fitness in hydrolysate as a mixture of fitness in its components. By examining outliers in this model, we identified methylglyoxal as a previously unknown component of hydrolysate. Our work provides a general strategy to dissect how microbes respond to a complex chemical stress and should enable further engineering of hydrolysate tolerance

Polylectrolyte- versus membrane-coated electrodes for energy production by Capmix salinity exchange methods

La versión final publicada se puede encontrar en: Journal of Power Sources, 302(20): 387-393 (2016). http://dx.doi.org/10.1016/j.jpowsour.2015.10.076In this paper we analyze the energy and power achievable by means of a re- cently proposed salinity gradient technique for energy production. The method, denominated soft electrode or SE, is based on the potential di erence that can be generated between two porous electrodes coated with cationic and anionic polyelectrolytes. It is related to the Capacitive Donnan Potential (CDP) tech- nique, where the electrical potential variations are mostly related to the Donnan potential, of ion-selective membranes in the case of CDP, and of the polyelec- trolyte coating in SE. It is found that although SE is comparable to CDP in terms of energy production, it presents slower rates of voltage change, and lower achieved power. The separate analysis of the response of positively and neg- atively coated electrodes shows that the latter produces most of the voltage rise and also of the response delay. These results, together with electrokinetic techniques, give an idea on how the two types of polyelectrolytes adsorb on the carbon surface and a ect di erently the di usion layer. It is possible to suggest that the SE technique is a promising one, and it may overcome the drawbacks associated to the use of membranes in CDP.MINECO FIS2013-47666-C3-1-RJunta de Andalucía, PE2012-FQM0694European Union 7th Framework Programme (FP7/2007–2013) under agreement No. 25686

The incidence of breast cancer in the General Practice Research Database compared with national cancer registration data

Breast cancer incidence rates in the UK from 1990 to 1996 among women aged 35–69 estimated from the General Practice Research Database (GPRD) were closely similar to those reported by the Office for National Statistics from cancer registration data (ONS). The GPRD is a valuable and up-to-date resource for further study of the incidence of breast cancer in the UK as well as changes in cancer treatment and their relation to survival trends. © 2000 Cancer Research Campaign http://www.bjcancer.co

Increasing access to consumer health organisations among patients with chronic disease - a randomised trial of a print-based intervention

To assess whether a print-based intervention led to increased contact with consumer health organisations (CHOs) by general practice patients with chronic disease. CHOs can enhance people's capacity to manage chronic illness by providing information, education and psychosocial support. However, these organisations appear to be grossly under-utilised by patients and clinicians. A total of 276 patients completed a computer-assisted telephone interview before randomisation to an intervention (n = 141) or control (n = 135) group. The intervention consisted of mailed printed materials designed to encourage contact with a CHO relevant to the patient's main diagnosed chronic condition. Follow-up interviews were conducted 4 and 12 months later. Patients with conditions other than diabetes who received the intervention were twice as likely as those in the control group to contact a consumer health organisation during the 12-month study period: 41% versus 21% (P < 0.001). No such effect was found for diabetes patients, probably because of pre-existing high levels of contact with diabetes organisations. The intervention package received strong patient endorsement. Low-intensity interventions may be effective in improving access to CHOs for patients with chronic disease

Are chimpanzees really so poor at understanding imperative pointing? Some new data and an alternative view of canine and ape social cognition

There is considerable interest in comparative research on different species’ abilities to respond to human communicative cues such as gaze and pointing. It has been reported that some canines perform significantly better than monkeys and apes on tasks requiring the comprehension of either declarative or imperative pointing and these differences have been attributed to domestication in dogs. Here we tested a sample of chimpanzees on a task requiring comprehension of an imperative request and show that, though there are considerable individual differences, the performance by the apes rival those reported in pet dogs. We suggest that small differences in methodology can have a pronounced influence on performance on these types of tasks. We further suggest that basic differences in subject sampling, subject recruitment and rearing experiences have resulted in a skewed representation of canine abilities compared to those of monkeys and apes

Self-pulsing oxide-confined vertical-cavity lasers with ultralow operating current

Includes bibliographical references (page 460).Selectively oxidised vertical-cavity lasers which exhibit self-pulsatin glasing at currents as low as 470nA are reported. Characteristics including linearly polarised emission, narrow linewidths and coherent near- and far-field diffraction indicate that these devices operate as lasers at DC currents 1mA