Gaseous Monitoring for the Integrated Life Support System at Langley Research Center

The Integrated Life Support System was conceived to study the problems of integrating regenerative equipment designed to operate in a negligible gravitational field. It is the first to fully integrate the three major contributors to atmospheric contamination: man, machine, and materials

70 Years of Human Rights in Global Health: Drawing on a Contentious Past to Secure a Hopeful Future

The Universal Declaration of Human Rights, adopted on Dec 10, 1948, established a modern human rights foundation that has become a cornerstone of global health, central to public health policies, programmes, and practices. To commemorate the 70th anniversary of this seminal declaration, we trace the evolution of human rights in global health, linking the past, present, and future of health as a human right. This future remains uncertain. As contemporary challenges imperil continuing advancements, threatening both human rights protections and global health governance, the future will depend, as it has in the past, on sustained political engagement to realise human rights in global health

Nanoscale spatially resolved infrared spectra from single microdroplets

Droplet microfluidics has emerged as a powerful platform allowing a large number of individual reactions to be carried out in spatially distinct microcompartments. Due to their small size, however, the spectroscopic characterisation of species encapsulated in such systems remains challenging. In this paper, we demonstrate the acquisition of infrared spectra from single microdroplets containing aggregation-prone proteins. To this effect, droplets are generated in a microfluidic flow-focussing device and subsequently deposited in a square array onto a ZnSe prism using a micro stamp. After drying, the solutes present in the droplets are illuminated locally by an infrared laser through the prism, and their thermal expansion upon absorption of infrared radiation is measured with an atomic force microscopy tip, granting nanoscale resolution. Using this approach, we resolve structural differences in the amide bands of the spectra of monomeric and aggregated lysozyme from single microdroplets with picolitre volume.Comment: 5 pages, 3 Figure

Adenomatous polyposis coli is required for early events in the normal growth and differentiation of the developing cerebral cortex

<p>Abstract</p> <p>Background</p> <p>Adenomatous polyposis coli (Apc) is a large multifunctional protein known to be important for Wnt/β-catenin signalling, cytoskeletal dynamics, and cell polarity. In the developing cerebral cortex, <it>Apc </it>is expressed in proliferating cells and its expression increases as cells migrate to the cortical plate. We examined the consequences of loss of Apc function for the early development of the cerebral cortex.</p> <p>Results</p> <p>We used <it>Emx1</it>^{<it>Cre </it>}to inactivate <it>Apc </it>specifically in proliferating cerebral cortical cells and their descendents starting from embryonic day 9.5. We observed reduction in the size of the mutant cerebral cortex, disruption to its organisation, and changes in the molecular identity of its cells. Loss of Apc leads to a decrease in the size of the proliferative pool, disrupted interkinetic nuclear migration, and increased apoptosis. β-Catenin, pericentrin, and N-cadherin proteins no longer adopt their normal high concentration at the apical surface of the cerebral cortical ventricular zone, indicating that cell polarity is disrupted. Consistent with enhanced Wnt/β-catenin signalling resulting from loss of Apc we found increased levels of TCF/LEF-dependent transcription and expression of endogenous Wnt/β-catenin target genes (<it>Axin2 </it>(<it>conductin</it>), <it>Lef1</it>, and <it>c-myc</it>) in the mutant cerebral cortex. In the <it>Apc </it>mutant cerebral cortex the expression of transcription factors <it>Foxg1</it>, <it>Pax6</it>, <it>Tbr1</it>, and <it>Tbr2 </it>is drastically reduced compared to normal and many cells ectopically express <it>Pax3</it>, <it>Wnt1</it>, and <it>Wt1 </it>(but not <it>Wnt2b</it>, <it>Wnt8b</it>, <it>Ptc</it>, <it>Gli1</it>, <it>Mash1</it>, <it>Olig2</it>, or <it>Islet1</it>). This indicates that loss of Apc function causes cerebral cortical cells to lose their normal identity and redirect to fates normally found in more posterior-dorsal regions of the central nervous system.</p> <p>Conclusion</p> <p>Apc is required for multiple aspects of early cerebral cortical development, including the regulation of cell number, interkinetic nuclear migration, cell polarity, and cell type specification.</p

Normal ventral telencephalic expression of Pax6 is required for normal development of thalamocortical axons in embryonic mice

<p>Abstract</p> <p>Background</p> <p>In addition to its well-known expression in dorsal telencephalic progenitor cells, where it regulates cell proliferation and identity, the transcription factor Pax6 is expressed in some ventral telencephalic cells, including many postmitotic neurons. Its functions in these cells are unknown.</p> <p>Results</p> <p>We generated a new floxed allele of <it>Pax6 </it>and tested the consequences of a highly specific ventral telencephalic depletion of Pax6. We used the <it>Six3</it>^{<it>A1A2</it>}-<it>Cre </it>allele that drives production of Cre recombinase in a specific region of Pax6-expression close to the internal capsule, through which thalamic axons navigate to cerebral cortex. Depletion in this region caused many thalamic axons to take aberrant routes, either failing to turn normally into ventral telencephalon to form the internal capsule or exiting the developing internal capsule ventrally. We tested whether these defects might have resulted from abnormalities of two structural features proposed to guide thalamic axons into and through the developing internal capsule. First, we looked for the early pioneer axons that project from the region of the future internal capsule to the thalamus and are thought to guide thalamocortical axons to the internal capsule: we found that they are present in conditional mutants. Second, we examined the development of the corridor of Islet1-expressing cells that guides thalamic axons through ventral telencephalon and found that it was broader and less dense than normal in conditional mutants. We also examined corticofugal axons that are thought to interact with ascending thalamocortical axons, resulting in each set providing guidance to the other, and found that some are misrouted to lateral telencephalon.</p> <p>Conclusion</p> <p>These findings indicate that ventral telencephalic Pax6 is important for formation of the Islet1-expressing corridor and the thalamic and cortical axons that grow through it. We suggest that Pax6 might affect thalamic axonal growth indirectly via its effect on the corridor.</p

Electronic Structure and Light-Induced Conductivity of a Transparent Refractory Oxide

Combined first-principles and experimental investigations reveal the underlying mechanism responsible for a drastic change of the conductivity (by 10 orders of magnitude) following hydrogen annealing and UV irradiation in a transparent oxide, 12CaO · 7Al2O3, found by Hayashi et al. [Nature (London) 419, 462 (2002).] The charge transport associated with photoexcitation of an electron from H- occurs by electron hopping.We identify the atoms participating in the hops, determine the exact paths for the carrier migration, estimate the temperature behavior of the hopping transport, and predict a way to enhance the conductivity by specific doping

Tunable Conductivity and Conduction Mechanism in a UV light activated electronic conductor

A tunable conductivity has been achieved by controllable substitution of a novel UV light activated electronic conductor. The transparent conducting oxide system H-doped Ca12-xMgxAl14O33 (x = 0; 0.1; 0.3; 0.5; 0.8; 1.0) presents a conductivity that is strongly dependent on the substitution level and temperature. Four-point dc-conductivity decreases with x from 0.26 S/cm (x = 0) to 0.106 S/cm (x = 1) at room temperature. At each composition the conductivity increases (reversibly with temperature) until a decomposition temperature is reached; above this value, the conductivity drops dramatically due to hydrogen recombination and loss. The observed conductivity behavior is consistent with the predictions of our first principles density functional calculations for the Mg-substituted system with x=0, 1 and 2. The Seebeck coefficient is essentially composition- and temperature-independent, the later suggesting the existence of an activated mobility associated with small polaron conduction. The optical gap measured remains constant near 2.6 eV while transparency increases with the substitution level, concomitant with a decrease in carrier content.Comment: Submitted for publicatio