38 research outputs found
Helmet of a laminate construction of polycarbonate and polysulfone polymeric material
An article of laminate construction is disclosed which is comprised of an underlayer of polycarbonate polymer material to which is applied a chemically resistant outer layer of polysulfone. The layers which are joined by compression-heat molding, are molded to form the shape of a body protective shell such as a space helmet comprising a shell of polycarbonate, polysulfone laminate construction attached at its open end to a sealing ring adapted for connection to a space suit. The front portion of the shell provides a transparent visor for the helmet. An outer visor of polycarbonate polysulfone laminate construction is pivotally mounted to the sealing ring for covering the transparent visor portion of the shell during extravehicular activities. The polycarbonate under layer of the outer visor is coated on its inner surface with a vacuum deposit of gold to provide additional thermal radiation resistance
Hazards protection for space suits and spacecraft
A flexible multi-layered covering article for protection against the hazards of exposure to the environment of outer space is disclosed. The covering includes an outer layer section comprising an outermost lamina of woven expanded tetrafluoroethylene yarns (Gore Tex) for protecting against abrasion and tearing, an underlying weave of meta-aramid yarns (Nomex) and para-aramid yarns (Kevlar) for particle impart protection, and electrostatic charge dissipation and control system incorporated therein, and a chemical contaminants control barrier applied as a coating. A middle section includes a succession of thermal insulating layers of polymeric thermoplastic or thermoforming material, each of which is coated with a metal deposit of high infra-red emissivity and low solar radiation absorption characteristics and separated from adjacent insulating layers by a low thermal conductance material. The covering further includes a radiation attenuating layer of a tungsten-loaded polymeric elastomer binder for protecting against bremsstrahlung radiation and an inner layer of rip-stop polyester material for abrasion protection. A chloroprene coating may be supplied the polyester-material for added micrometeroid protection. Securing means of low heat conductance material secures the multi-layers together as a laminar composite
Improving Orbit Estimates for Incomplete Orbits with a New Approach to Priors -- with Applications from Black Holes to Planets
We propose a new approach to Bayesian prior probability distributions
(priors) that can improve orbital solutions for low-phase-coverage orbits,
where data cover less than approximately 40% of an orbit. In instances of low
phase coverage such as with stellar orbits in the Galactic center or with
directly-imaged exoplanets, data have low constraining power and thus priors
can bias parameter estimates and produce under-estimated confidence intervals.
Uniform priors, which are commonly assumed in orbit fitting, are notorious for
this. We propose a new observable-based prior paradigm that is based on
uniformity in observables. We compare performance of this observable-based
prior and of commonly assumed uniform priors using Galactic center and
directly-imaged exoplanet (HR 8799) data. The observable-based prior can reduce
biases in model parameters by a factor of two and helps avoid under-estimation
of confidence intervals for simulations with less than about 40% phase
coverage. Above this threshold, orbital solutions for objects with sufficient
phase coverage such as S0-2, a short-period star at the Galactic center with
full phase coverage, are consistent with previously published results. Below
this threshold, the observable-based prior limits prior influence in regions of
prior dominance and increases data influence. Using the observable-based prior,
HR 8799 orbital analyses favor lower eccentricity orbits and provide stronger
evidence that the four planets have a consistent inclination around 30 degrees
to within 1-sigma. This analysis also allows for the possibility of
coplanarity. We present metrics to quantify improvements in orbital estimates
with different priors so that observable-based prior frameworks can be tested
and implemented for other low-phase-coverage orbits.Comment: Published in AJ. 23 pages, 14 figures. Monte Carlo chains are
available in the published article, or are available upon reques
Method for forming a glove attachment
An attachment principally for the palm of an astronaut glove to enhance the gripping area of the palm without detracting from the flexibility and utility of the glove is presented. The attachment is a composite construction formed from a layer of silicone rubber having an outer surface with a friction configuration and another layer of silicone rubber in which a Nomex Aramid mesh fabric is embedded prior to curing. The method of construction involves the use of a mold with a friction configuration surface. A first layer of silicone rubber or sealant is disposed in the mold and allowed to set for an hour. A second layer of silicone rubber or sealant is layered over the first layer and leveled. A Nomex Aramid mesh fabric is embedded into the second layer and the composite is permitted to cure. When cured, a configured area of the composite construction is glued or stitched to the palm area of the glove
Testing the gravitational theory with short-period stars around our Galactic Center
Motion of short-period stars orbiting the supermassive black hole in our
Galactic Center has been monitored for more than 20 years. These observations
are currently offering a new way to test the gravitational theory in an
unexplored regime: in a strong gravitational field, around a supermassive black
hole. In this proceeding, we present three results: (i) a constraint on a
hypothetical fifth force obtained by using 19 years of observations of the two
best measured short-period stars S0-2 and S0-38 ; (ii) an upper limit on the
secular advance of the argument of the periastron for the star S0-2 ; (iii) a
sensitivity analysis showing that the relativistic redshift of S0-2 will be
measured after its closest approach to the black hole in 2018.Comment: 4 pages, 2 figures, proceedings of the 52nd Rencontres de Moriond,
Gravitation Sessio
Phase 1 Trial of Fruquintinib in Patients with Advanced Solid Tumors: Results of the Dose Escalation Phase.
Background: Fruquintinib (Fruq) is a potent, highly selective, novel vascular endothelial growth factor receptor (VEGFR) -1, -2, and -3 tyrosine kinase inhibitor. In the Phase III FRESCO trial1 that led to the drug approval in China, Fruq improved the median overall survival in patients with metastatic colorectal cancer (mCRC) in the third line or later setting when compared to placebo (9.3 vs 6.6 months); hazard ratio 0.65 (95% CI, 0.51-0.83; P \u3c .001),
Methods: This is a Phase 1 open-label, dose escalation/dose expansion study conducted in the US (NCT03251378). The primary objectives are to evaluate the safety and tolerability of Fruq in pts with advanced solid tumors and to determine the recommended phase 2 dose (RP2D). A secondary objective is to evaluate anticancer activity. There were 2 dose cohorts: 3mg and 5 mg qd, each on a 3 weeks on, 1 week (3/1) off schedule.
Results: Fourteen pts were enrolled: 7 (6 evaluable) pts in each dose cohort. Fruq was generally well-tolerated. There was 1 dose-limiting toxicity (DLT) of grade 4 hypertension in the 3 mg cohort, and no DLTs in the 5 mg cohort. The RP2D was 5 mg qd (3/1), which is also the approved dose in China. Two other serious adverse events were reported: colon obstruction and left breast cellulitis; neither was suspected to be drug-related. All 14 pts reported AEs; the most common were vomiting (57%), nausea (50%), constipation (50%, proteinuria (50%), hypertension (50%), dysphonia (43%), anorexia (36%), and dyspepsia (36%). Ten pts were evaluable for best objective response; results were partial response 3, stable disease 6, and disease progression 1. Objective response rate was 3/14 (21.4%) and disease control rate was 9/14 (64.3%). Mean duration on study drug was 5.3 months.
Conclusion: Fruq is generally well-tolerated in heavily pretreated patients. The RP2D in US pts is 5 mg qd (3/1). The safety profile is consistent with that of other anti-angiogenic tyrosine kinase inhibitors. There is preliminary evidence of anticancer activity in pts with advanced solid tumors. The dose expansion phase of the study is ongoing. Further investigation of Fruq in pts with mCRC is planned. 1. JAMA 2018; 319:2486
A population of dust-enshrouded objects orbiting the Galactic black hole
The central 0.1 parsecs of the Milky Way host a supermassive black hole
identified with the position of the radio and infrared source Sagittarius A*, a
cluster of young, massive stars (the S stars) and various gaseous features.
Recently, two unusual objects have been found to be closely orbiting
Sagittarius A*: the so-called G sources, G1 and G2. These objects are
unresolved (having a size of the order of 100 astronomical units, except at
periapse, where the tidal interaction with the black hole stretches them along
the orbit) and they show both thermal dust emission and line emission from
ionized gas. G1 and G2 have generated attention because they appear to be
tidally interacting with the supermassive Galactic black hole, possibly
enhancing its accretion activity. No broad consensus has yet been reached
concerning their nature: the G objects show the characteristics of gas and dust
clouds but display the dynamical properties of stellar-mass objects. Here we
report observations of four additional G objects, all lying within 0.04 parsecs
of the black hole and forming a class that is probably unique to this
environment. The widely varying orbits derived for the six G objects
demonstrate that they were commonly but separately formed
Stellar Populations in the Central 0.5 pc of Our Galaxy III: The Dynamical Sub-structures
We measure the 3D kinematic structures of the young stars within the central
0.5 parsec of our Galactic Center using the 10 m telescopes of the W.~M.~Keck
Observatory over a time span of 25 years. Using high-precision measurements of
positions on the sky, and proper motions and radial velocities from new
observations and the literature, we constrain the orbital parameters for each
young star. Our results show two statistically significant sub-structures: a
clockwise stellar disk with 18 candidate stars, as has been proposed before,
but with an improved disk membership; a second, almost edge-on plane of 10
candidate stars oriented East-West on the sky that includes at least one IRS 13
star. We estimate the eccentricity distribution of each sub-structure and find
that the clockwise disk has = 0.39 and the edge-on plane has =
0.68. We also perform simulations of each disk/plane with incompleteness and
spatially-variable extinction to search for asymmetry. Our results show that
the clockwise stellar disk is consistent with a uniform azimuthal distribution
within the disk. The edge-on plane has an asymmetry that cannot be explained by
variable extinction or incompleteness in the field. The orientation, asymmetric
stellar distribution, and high eccentricity of the edge-on plane members
suggest that this structure may be a stream associated with the IRS 13 group.
The complex dynamical structure of the young nuclear cluster indicates that the
star formation process involved complex gas structures and dynamics and is
inconsistent with a single massive gaseous disk.Comment: 41 pages, 26 figures, 13 tables, 2 appendices. Accepted for
publication in Ap
Burkitt lymphoma masquerading as cardiac tamponade
A 61 year old man presented with diffuse large B cell lymphoma of the skin of the back of the shoulder which was excised and treated with chemotherapy (CHOP regime) in 1998. He was in complete remission till he presented in 2002 with extranodal marginal zone lymphoma of the parotid gland for which he underwent superficial parotidectomy and radiotherapy. He continued in remission till 2006 when he presented with recurrent pericardial effusion and tamponade. At median sternotomy, pericardial effusion was drained, an anterior pericardiectomy was done and a left posterior pericardial window made, and an enlarged hard paraaortic lymph node excised. Histology, immunocytochemistry and chromosome analysis revealed Burkitt lymphoma. Patient underwent chemotherapy with CODOX-M regime and continues in remission. This report is unusual on account of the highly atypical presentation of Burkitt lymphoma as cardiac tamponade, only a few cases having been reported previously, the occurrence of three lymphomas of different pathological and genomic profiles in one patient over a period of eight years and the relatively slow rate of growth of an otherwise fulminant tumour with high tumour doubling time. A review of literature with special emphasis on chromosomal diagnosis, transformation of other lymphomas into Burkitt lymphoma and mediastinal and cardiac involvement with Burkitt lymphoma is presented