Revisiting Nuclear Thermal Propulsion for Human Mars Exploration

Nuclear Thermal Propulsion (NTP) has long been considered as a viable in-space transportation alternative for delivering crew and cargo to the Martian system. While technology development work in nuclear propulsion has continued over the year, general interest in NTP propulsion applications has historically been tied directly to the ebb and flow of interest in sending humans to explore Mars. As far back as the 1960s, plans for NTP-based human Mars exploration have been proposed and periodically revisited having most recently been considered as part of NASA Design Reference Architecture (DRA) 5.0. NASA has been investigating human Mars exploration strategies tied to its current Journey to Mars for the past few years however, NTP has only recently been added into the set of alternatives under consideration for in-space propulsion under the Mars Study Capability (MSC) team, formerly the Evolvable Mars Campaign (EMC) team. The original charter of the EMC was to find viable human Mars exploration approaches that relied heavily on technology investment work already underway, specifically related to the development of large Solar Electric Propulsion (SEP) systems. The EMC team baselined several departures from traditional Mars exploration ground rules to enable these types of architectures. These ground rule changes included lower energy conjunction class trajectories with corresponding longer flight times, aggregation of mission elements in cis-Lunar space rather than Low Earth Orbit (LEO) and, in some cases, the pre-deployment of Earth return propulsion systems to Mars. As the MSC team continues to refine the in-space transportation trades, an NTP-based architecture that takes advantage of some of these ground rule departures is being introduced

Forced Sale Risk: Class, Race, and the Double Discount

What impact does a forced sale have upon a property owner\u27s wealth? And do certain characteristics of a property owner such as whether they are rich or poor or whether they are black or white, tend to affect the price yielded at a forced sale? This Article addresses arguments made by some courts and legal scholars who have claimed that certain types of forced sales result in wealth maximizing, economic efficiencies. The Article addresses such economic arguments by returning to first principles and reviewing the distinction between sales conducted under fair market value conditions and sales conducted under forced sale conditions. This analysis makes it clear that forced sales of real or personal property are conducted under conditions that are rarely likely to yield market value prices. In addition, the Article addresses the fact that judges and legal scholars have utilized a flawed economic analysis of forced sales in cases that often involve property that is owned by low- to middle-class property owners in part because those who are wealthier own their property under more stable ownership structures or utilize private ordering to avoid the chance that a court might order a forced sale under the default rules of certain common ownership structures. The Article also raises the possibility for the first time that the race or ethnicity of a property owner may affect the sales price for property sold at a forced sale, resulting in a double discount, i.e. a discount from market value for the forced sale and a further discount attributable to the race of the property owner. If minorities are more susceptible to forced sales of their property than white property owners or if there does exist a phenomenon in which minorities suffer a double discount upon the sale of their property at a forced sale, then forced sales of minority-owned property could be contributing to persistent and yawning racial wealth gaps

An Unusually Colored Red-backed Salamander (Plethodon cinerus) From Northern Virginia

We describe an orange-pink, patternless, translucent morph of the Red-backed Salamander (Plethodon cinereus) found in northern Virginia on 27 September 2001. This is the first description of this unusual phenotype in this terrestrial salamander

The Origin And Loss Of Periodic Patterning In The Turtle Shell

The origin of the turtle shell over 200 million years ago greatly modified the amniote body plan, and the morphological plasticity of the shell has promoted the adaptive radiation of turtles. The shell, comprising a dorsal carapace and a ventral plastron, is a layered structure formed by basal endochondral axial skeletal elements (ribs, vertebrae) and plates of bone, which are overlain by keratinous ectodermal scutes. Studies of turtle development have mostly focused on the bones of the shell; however, the genetic regulation of the epidermal scutes has not been investigated. Here, we show that scutes develop from an array of patterned placodes and that these placodes are absent from a soft-shelled turtle in which scutes were lost secondarily. Experimentally inhibiting Shh, Bmp or Fgf signaling results in the disruption of the placodal pattern. Finally, a computational model is used to show how two coupled reaction-diffusion systems reproduce both natural and abnormal variation in turtle scutes. Taken together, these placodal signaling centers are likely to represent developmental modules that are responsible for the evolution of scutes in turtles, and the regulation of these centers has allowed for the diversification of the turtle shell

Identification and analysis of in planta expressed genes of Magnaporthe oryzae

<p>Abstract</p> <p>Background</p> <p>Infection of plants by pathogens and the subsequent disease development involves substantial changes in the biochemistry and physiology of both partners. Analysis of genes that are expressed during these interactions represents a powerful strategy to obtain insights into the molecular events underlying these changes. We have employed expressed sequence tag (EST) analysis to identify rice genes involved in defense responses against infection by the blast fungus <it>Magnaporthe oryzae </it>and fungal genes involved in infectious growth within the host during a compatible interaction.</p> <p>Results</p> <p>A cDNA library was constructed with RNA from rice leaves (<it>Oryza sativa </it>cv. Hwacheong) infected with <it>M. oryzae </it>strain KJ201. To enrich for fungal genes, subtraction library using PCR-based suppression subtractive hybridization was constructed with RNA from infected rice leaves as a tester and that from uninfected rice leaves as the driver. A total of 4,148 clones from two libraries were sequenced to generate 2,302 non-redundant ESTs. Of these, 712 and 1,562 ESTs could be identified to encode fungal and rice genes, respectively. To predict gene function, Gene Ontology (GO) analysis was applied, with 31% and 32% of rice and fungal ESTs being assigned to GO terms, respectively. One hundred uniESTs were found to be specific to fungal infection EST. More than 80 full-length fungal cDNA sequences were used to validate <it>ab initio</it> annotated gene model of <it>M. oryzae</it> genome sequence.</p> <p>Conclusion</p> <p>This study shows the power of ESTs to refine genome annotation and functional characterization. Results of this work have advanced our understanding of the molecular mechanisms underpinning fungal-plant interactions and formed the basis for new hypothesis.</p

Concordance between a neuroradiologist, a consultant radiologist and trained reporting radiographers interpreting MRI head examinations: An empirical study

Introduction: This study assessed agreement between MRI reporting radiographers and a consultant radiologist compared with an index neuroradiologist when reporting MRI head (brain/internal auditory meati [IAMs]) examinations. The effect on patient management of any discordant reports was also examined. Methods: Two trained MRI reporting radiographers (RRs), a consultant radiologist (CR) and an index neuroradiologist (INR) reported on a random sample of 210 MRI examinations. The radiographers reported during clinical practice and the radiologists in clinical practice conditions. Two independent consultant physicians (neuro-rehabilitation and neuropsychiatry) compared these reports with the index neuroradiologist report for agreement and the clinical importance of discrepant reports. Results: Overall observer agreement between the RRs and CR was comparable in relation to agreement with the INR: RR; 93/210 (44.3%); and the CR; 83/210 (39.4%) for all head MRI examinations (p = 0.32). For brain examinations the difference was similar: RR; 64/180 (35.6%); and CR; 54/190 (30.0%), p = 0.26. Agreement rates for the IAMs examinations were identical, 29/30 (97.7%). For all head MRI examinations (n = 210) there was a very small observed difference of <0.5% in mean agreement between the reporting radiographers and the consultant radiologist (p = 0.92) for examinations where a major disagreement would have been likely to have led to a change in patient management. Conclusion: MRI reporting radiographers reported during clinical practice on MRI head examinations to a level of agreement comparable with a consultant radiologist. Implications for practice: This is an area in which radiographers could provide additional reporting roles to the reporting service to increase capacity. Wider potential benefits include cost-effectiveness and role development/retention of radiographers

Quantum phase transition in quantum dot trimers

We investigate a system of three tunnel-coupled semiconductor quantum dots in a triangular geometry, one of which is connected to a metallic lead, in the regime where each dot is essentially singly occupied. Both ferro- and antiferromagnetic spin-1/2 Kondo regimes, separated by a quantum phase transition, are shown to arise on tuning the interdot tunnel couplings and should be accessible experimentally. Even in the ferromagnetically-coupled local moment phase, the Kondo effect emerges in the vicinity of the transition at finite temperatures. Physical arguments and numerical renormalization group techniques are used to obtain a detailed understanding of the problem.Comment: 5 pages, 5 figure

An exploration of Service Design Jam and its ability to Foster Social Enterprise

Social enterprises (SE) are valued as innovative solutions to complex problems but require conditions to nurture and support them. Most support systems rely on individuals who already have an SE idea, and there is very little research on understanding what conditions can support to cultivate the willingness and motivation to engage individuals in this activity. An exploratory study was led to understand whether a particular event, Service Design Jams can provide such conditions. The paper introduces the study of the Lufbra Jam, organised at Loughborough University, from which two social enterprises, Crop Club in 2013, and FrenPal in 2014 emerged. Through literature review desirability and feasibility were extrapolated as key variables to the formation process of social enterprises. A focus group with three Lufbra Jam organisers was led to identify important organisational elements of the Jam that were perceived to have an impact on the formation of the successful SE thus influencing the perception of desirability and feasibility of SE in individuals. The integration of the two created a thematic matrix that was used to analyse findings from the research with the participants of the two successful SE Cases. The research findings suggest that Lufbra Jam enabled individuals to identify socially and environmentally focused issues and formulate service solutions that they deemed to be desirable and feasible ideas. It also provided an insight that winning and an enterprising workshop were important SDJ elements that helped teams to recognise their service ideas not only as feasible solutions but as SE opportunity for the team to take forward

An experimental study of the rearrangements of valence protons and neutrons amongst single-particle orbits during double {\beta} decay in 100Mo

The rearrangements of protons and neutrons amongst the valence single-particle orbitals during double {\beta} decay of 100Mo have been determined by measuring cross sections in (d,p), (p,d), (3He,{\alpha}) and (3He,d) reactions on 98,100Mo and 100,102Ru targets. The deduced nucleon occupancies reveal significant discrepancies when compared with theoretical calculations; the same calculations have previously been used to determine the nuclear matrix element associated with the decay probability of double {\beta} decay of the 100Mo system.Comment: 18 pages, 13 figures, 37 pages of supplemental informatio