A down-converting (DC) layer placed on the front side of a silicon solar cell has the potential to generate more than one low-energy photon for every incident high-energy photon. Recent theory has ...predicted that DC in conjunction with a silicon solar cell can achieve a conversion efficiency of up to 38.6%. This paper examines the application of rare-earth-doped inorganic materials for achieving external quantum efficiencies greater than unity and enhancing the conversion efficiency of silicon solar cells. Such DC mechanisms have been applied in similar phosphor materials used by the lighting and display industries. The opportunities for the DC of high-energy solar photons to multiple photons with energy greater than the silicon bandgap are discussed.
This paper discusses ways of reducing the two major losses encountered in a single-junction photovoltaic (PV) device—that of sub-band gap transmission and lattice thermalisation losses—via the ...application of passive luminescent devices called up- and down-converters, respectively. Down-conversion (DC) results in the generation of more than one lower energy photon being generated per incident high-energy photon, while up-conversion (UC) generates one photon with energy for every two or more sub-band gap photons absorbed. A related process of wavelength down-shifting (DS) is similar to DC except that the external quantum efficiency of the DS process is less than unity.
We revisit the system consisting of a neutron star that harbors a small, possibly primordial, black hole at its center, focusing on a nonspinning black hole embedded in a nonrotating neutron star. ...Extending earlier treatments, we provide an analytical treatment describing the rate of secular accretion of the neutron star matter onto the black hole, adopting the relativistic Bondi accretion formalism for stiff equations of state that we presented elsewhere. We use these accretion rates to sketch the evolution of the system analytically until the neutron star is completely consumed. We also perform numerical simulations in full general relativity for black holes with masses up to nine orders of magnitude smaller than the neutron star mass, including a simulation of the entire evolution through collapse for the largest black hole mass. We construct relativistic initial data for these simulations by generalizing the black hole puncture method to allow for the presence of matter, and evolve these data with a code that is optimally designed to resolve the vastly different length scales present in this problem. We compare our analytic and numerical results, and provide expressions for the lifetime of neutron stars harboring such endoparasitic black holes.
An up-converting material can generate one high-energy photon for every two or more incident low-energy photons. This material when placed on the rear side of a traditional bi-facial photovoltaic ...solar cell has the potential to increase the overall efficiency of the PV device by utilising sub-bandgap photons that would otherwise be transmitted through the device. This paper reviews and examines the application of rare-earth doped inorganic phosphors for achieving external quantum efficiencies for sub-bandgap photons for a bi-facial crystalline silicon photovoltaic device. The mechanisms for up-conversion are discussed and recent experimental results on a bi-facial silicon photovoltaic-upconversion device are analysed.
Clinical study correlating preoperative pulmonary function tests (PFTs) to radiographic measures of thoracic deformity severity in adolescent idiopathic scoliosis (AIS) patients.
To determine (1) the ...incidence of clinically relevant (<65% predicted value) pulmonary impairment in AIS patients; (2) if patients with more severe deformity have greater impairment of PFTs than those with lesser deformity; (3) the effect, if any, of juvenile onset deformity (onset<age 10) on preoperative PFTs.
Patients with late-onset (adolescent) spinal deformity are generally believed to have no respiratory morbidity except in severe curves exceeding 100°.
A large multicenter database of surgically treated AIS patients with Lenke 1 to Lenke 4 curves was queried to report preoperative PFTs and correlate them with radiographic measures of coronal, sagittal, and axial plane deformities.
Nineteen percent of 858 patients had <65% predicted forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) before surgery, and had larger main thoracic (MT) curves and greater axial rotation than those with predicted PFT values>65%. Patients with MT curves>70°, and especially >80°; proximal thoracic (PT) curves which were >30° or structural; or T5-T12 kyphosis<10° had significantly (P≤0.001) lower FEV1 or FVC compared to those with less deformity. Axial plane deformity did not correlate with PFT impairment. Juvenile-onset patients had greater PFT impairment than AIS patients, along with slightly larger MT curves. Patients who were braced before surgery had worse PFTs than those had no treatment before surgery.
Preoperative PFTs are clinically impaired in 19% of AIS patients, and correlate significantly with the MT and sagittal plane deformity severity, and with PT curve severity to a lesser degree. PFTs do not correlate with degree of axial deformity. From a purely pulmonary standpoint, attention directed to coronal and sagittal plane deformity correction appears warranted, to address the specific deformities which are associated with PFT impairment.
It has been argued recently that the initial dispersal of anatomically modern humans from Africa to southern Asia occurred before the volcanic “supereruption” of the Mount Toba volcano (Sumatra) at ...∼74,000 y before present (B.P.)—possibly as early as 120,000 y B.P. We show here that this “pre-Toba” dispersal model is in serious conflict with both the most recent genetic evidence from both Africa and Asia and the archaeological evidence from South Asian sites. We present an alternative model based on a combination of genetic analyses and recent archaeological evidence from South Asia and Africa. These data support a coastally oriented dispersal of modern humans from eastern Africa to southern Asia ∼60–50 thousand years ago (ka). This was associated with distinctively African microlithic and “backed-segment” technologies analogous to the African “Howiesons Poort” and related technologies, together with a range of distinctively “modern” cultural and symbolic features (highly shaped bone tools, personal ornaments, abstract artistic motifs, microblade technology, etc.), similar to those that accompanied the replacement of “archaic” Neanderthal by anatomically modern human populations in other regions of western Eurasia at a broadly similar date.
A two-step process, in which circulating levels of amyloid P are reduced and then anti–serum amyloid P antibody is given to activate macrophage clearance mechanisms of tissue deposits, appears to ...reduce amyloid deposits in liver and some other organs.
In systemic amyloidosis, the extracellular deposition of normally soluble plasma proteins as insoluble amyloid fibrils damages the structure and function of tissues and organs.
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Current treatment consists of support or replacement of failing organs and measures to reduce the abundance of the amyloid fibril precursor protein.
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,
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A sufficient reduction of precursor supply arrests the accumulation of amyloid and can reduce morbidity and mortality. However, amyloid regression is very slow and often does not occur at all, in contrast to the usually swift clearance of other extracellular debris and efficient tissue remodeling — for example, after trauma. At least 65% . . .
Accurately predicting soil moisture patterns in the landscape is a persistent challenge. In humid regions, topographic wetness indices (TWIs) are widely used to approximate relative soil moisture ...patterns. However, there are many ways to calculate TWIs and very few field studies have evaluated the different approaches – especially in the US. We calculated TWIs using over 400 unique formulations that considered different digital elevation model (DEM) resolutions (cell size), vertical precision of DEM, flow direction and slope algorithms, smoothing via low-pass filtering, and the inclusion of relevant soil properties. We correlated each TWI with observed patterns of soil moisture at five agricultural fields in central NY, USA, with each field visited five to eight times between August and November 2012. Using a mixed effects modeling approach, we were able to identify optimal TWI formulations applicable to moderate relief agricultural settings that may provide guidance for practitioners and future studies. Overall, TWIs were moderately well correlated with observed soil moisture patterns; in the best case the relationship between TWI and soil moisture had an average R2 and Spearman correlation value of 0.61 and 0.78, respectively. In all cases, fine-scale (3 m) lidar-derived DEMs worked better than USGS 10 m DEMs and, in general, including soil properties improved correlations.
Transparent photovoltaics provide diverse levels of average visible transmittance (AVT) along with concurrent light harvesting, making glass façades and windows accessible for photovoltaics. However, ...improvements in power conversion efficiency (PCE) and aesthetics are required to enhance commercial viability and public acceptance. This work presents the scalable fabrication of efficient micro-patterned translucent perovskite photovoltaics at optical qualities suited for building integration. Optimized laser-scribed transparent areas (25 μm) mitigate detrimental effects on electrical performance, featuring perovskite solar cells with 44% AVT and demonstrating industrial glass quality through neutral color rendering (CRI 97) and only 3% haze. Highlighting scalability, submodules yield PCEs of 9.0% at 32% AVT (4 cm
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aperture area). The transfer to two-terminal perovskite-perovskite tandem solar cells exhibiting PCEs of 17.7% at 12% AVT and 11.1% at 31% AVT demonstrates the first translucent perovskite tandem photovoltaics. Lastly, the novel concept of transmittance gradients with 7% cm
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absolute change in AVT and 12.0% PCE for submodules is presented, providing a foundation for architectural individualizations.
This work presents the scalable fabrication of micro-patterned translucent perovskite single-junction and tandem PV with optical quality suited for BIPV and introduces the novel concept of transmittance gradients for architectural individualization.
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