1,144 research outputs found
Regenerable metallic oxide systems for removal of carbon dioxide: A concept
Design concepts for portable canisters for removal of carbon dioxide are described. One is screen pack configuration consisting of brazed rectangular canister with four metal oxide packs inserted. Other is radial flow canister with perforated central tube. Methods of production and operating principles are presented
Solid amine compounds as sorbents for carbon dioxide: A concept
Solid amine compounds were examined as possible absorbents for removal of carbon dioxide in life support systems of type which may be employed in high altitude aircraft, spacecraft, or submarines. Many solid amine compounds release absorbed carbon dioxide when heated in vacuum, therefore, when properly packaged spent amine compounds can be readily regenerated and put back into service
Phosphonium chloride for thermal storage
Development of systems for storage of thermal energy is discussed. Application of phosphonium chloride for heat storage through reversible dissociation is described. Chemical, physical, and thermodynamic properties of phosphonium chloride are analyzed and dangers in using phosphonium chloride are explained
Advanced extravehicular protective system Interim report, 1 Jul. 1970 - 31 May 1971
Regenerable portable life support systems concepts for EVA use in 1980 and technology assessmen
Analytic Representation of The Dirac Equation
In this paper we construct an analytical separation (diagonalization) of the
full (minimal coupling) Dirac equation into particle and antiparticle
components. The diagonalization is analytic in that it is achieved without
transforming the wave functions, as is done by the Foldy-Wouthuysen method, and
reveals the nonlocal time behavior of the particle-antiparticle relationship.
We interpret the zitterbewegung and the result that a velocity measurement (of
a Dirac particle) at any instant in time is, as reflections of the fact that
the Dirac equation makes a spatially extended particle appear as a point in the
present by forcing it to oscillate between the past and future at speed c. From
this we infer that, although the form of the Dirac equation serves to make
space and time appear on an equal footing mathematically, it is clear that they
are still not on an equal footing from a physical point of view. On the other
hand, the Foldy-Wouthuysen transformation, which connects the Dirac and square
root operator, is unitary. Reflection on these results suggests that a more
refined notion (than that of unitary equivalence) may be required for physical
systems
Exhaled nitric oxide during infancy as a risk factor for asthma and airway hyperreactivity
Childhood asthma is often characterised by elevated exhaled nitric oxide (eNO), decreased lung function, increased airway reactivity and atopy; however, our understanding of when these phenotypic airway characteristics develop remains unclear. This study evaluated whether eNO, lung function, airway reactivity and immune characteristics during infancy are risk factors of asthma at age 5 years. Infants with eczema, enrolled prior to wheezy illness (n=116), had eNO, spirometry, airway reactivity and allergen sensitisation assessed at entry to the study and repeated at age 5 years (n=90). Increasing eNO at entry was associated with an increased risk of asthma (p=0.037) and increasing airway reactivity (p=0.015) at age 5 years. Children with asthma at 5 years of age had a greater increase in eNO between infancy and age 5 years compared with those without asthma (p=0.002). Egg sensitisation at entry was also associated with an increased risk of asthma (p=0.020), increasing eNO (p = 0.002) and lower forced expiratory flows (p=0.029) as a 5 year-old. Our findings suggest that, among infants at high risk for developing asthma, eNO early in life may provide important insights into the subsequent risk of asthma and its airway characteristics
An implantable microdevice to perform high-throughput in vivo drug sensitivity testing in tumors
Current anticancer chemotherapy relies on a limited set of in vitro or indirect prognostic markers of tumor response to available drugs. A more accurate analysis of drug sensitivity would involve studying tumor response in vivo. To this end, we have developed an implantable device that can perform drug sensitivity testing of several anticancer agents simultaneously inside the living tumor. The device contained reservoirs that released microdoses of single agents or drug combinations into spatially distinct regions of the tumor. The local drug concentrations were chosen to be representative of concentrations achieved during systemic treatment. Local efficacy and drug concentration profiles were evaluated for each drug or drug combination on the device, and the local efficacy was confirmed to be a predictor of systemic efficacy in vivo for multiple drugs and tumor models. Currently, up to 16 individual drugs or combinations can be assessed independently, without systemic drug exposure, through minimally invasive biopsy of a small region of a single tumor. This assay takes into consideration physiologic effects that contribute to drug response by allowing drugs to interact with the living tumor in its native microenvironment. Because these effects are crucial to predicting drug response, we envision that these devices will help identify optimal drug therapy before systemic treatment is initiated and could improve drug response prediction beyond the biomarkers and in vitro and ex vivo studies used today. These devices may also be used in clinical drug development to safely gather efficacy data on new compounds before pharmacological optimization.National Cancer Institute (U.S.) (Innovative Molecular Analysis Technologies Program R21-CA177391)Kibur Medical, Inc
Measuring kinetic coefficients by molecular dynamics simulation of zone melting
Molecular dynamics simulations are performed to measure the kinetic
coefficient at the solid-liquid interface in pure gold. Results are obtained
for the (111), (100) and (110) orientations. Both Au(100) and Au(110) are in
reasonable agreement with the law proposed for collision-limited growth. For
Au(111), stacking fault domains form, as first reported by Burke, Broughton and
Gilmer [J. Chem. Phys. {\bf 89}, 1030 (1988)]. The consequence on the kinetics
of this interface is dramatic: the measured kinetic coefficient is three times
smaller than that predicted by collision-limited growth. Finally,
crystallization and melting are found to be always asymmetrical but here again
the effect is much more pronounced for the (111) orientation.Comment: 8 pages, 9 figures (for fig. 8 : [email protected]). Accepted for
publication in Phys. Rev.
Restriction of AID activity and somatic hypermutation by PARP-1
Affinity maturation of the humoral immune response depends on somatic hypermutation (SHM) of immunoglobulin (Ig) genes, which is initiated by targeted lesion introduction by activation-induced deaminase (AID), followed by error-prone DNA repair. Stringent regulation of this process is essential to prevent genetic instability, but no negative feedback control has been identified to date. Here we show that poly(ADP-ribose) polymerase-1 (PARP-1) is a key factor restricting AID activity during somatic hypermutation. Poly(ADP-ribose) (PAR) chains formed at DNA breaks trigger AID-PAR association, thus preventing excessive DNA damage induction at sites of AID action. Accordingly, AID activity and somatic hypermutation at the Ig variable region is decreased by PARP-1 activity. In addition, PARP-1 regulates DNA lesion processing by affecting strand biased A:T mutagenesis. Our study establishes a novel function of the ancestral genome maintenance factor PARP-1 as a critical local feedback regulator of both AID activity and DNA repair during Ig gene diversification
Geriatric Assessment as a Predictor of Tolerance, Quality of Life, and Outcomes in Older Patients With Head and Neck Cancers and Lung Cancers Receiving Radiation Therapy
Purpose To evaluate the association between functional status based on a geriatric assessment (GA) and outcomes of tolerance to treatment in patients with lung or head and neck cancer receiving radiation therapy (RT) or chemoradiation (CRT). Methods and Materials A prospective cohort study was conducted in patients aged ≥65 years with head and neck cancer or lung cancer undergoing curative intent RT or CRT. Pretreatment GA, health-related quality of life (HRQoL), and patient-reported outcomes (PRO) were obtained. Questionnaires were repeated biweekly during RT and at 6 weeks after treatment. Dysfunction was defined as scores 3-day treatment delay, change in RT or CRT regimen, or death. Associations of dysfunction with tolerance to radiation therapy, HRQoL changes, and PRO ratings were evaluated. Results Of the 50 patients accrued, 46 had evaluable data. Mean age was 72.5 years (range, 65-92 years). At baseline, 37% had dysfunction. Poor tolerance to RT or CRT occurred in 39%. There was no association between dysfunction and tolerance. Patients with dysfunction had lower baseline HRQoL scores. From baseline to end of RT, those with baseline dysfunction had less of a decline in Role Functioning (P=.01) and Global Health Score (P=.04) domains. However, from end of RT to 6-week follow-up, those with dysfunction were more likely to continue to drop in the Physical, Role Functioning, and Social domains (all P<.01). Dysfunction at baseline was also associated with higher severity of certain PROs. Conclusions Pretreatment dysfunction was associated with continued decline and lack of recovery of HRQoL in this patient population. Larger studies could further elucidate the GA's predictive value
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