Fabrication of Large Mechanically Flexible Multi-Layered PDMS Optical Devices

Mechanically flexible large area polydimethylsiloxane (PDMS) optical devices are fabricated using soft-lithography techniques based on replica moulding. These non-rigid optical devices can be designed as sheets to act as either light concentrators (collectors) or diffusers (illuminators) based on the position and geometry of micro-optical structures (MOSs) embedded within the sheet or imprinted on its surface. The active surface area of the device can range from less than a sq. cm to several sq. m. The performance of the large area optical device is a function of the location and geometry of micro-optical structures, thickness and shape of the flexible waveguide, core and cladding material (ie. refractive indices), and the wavelength of the incident light source. A centrifugal casting technique that simultaneously de-gasses and fills a patterned, thin mould cavity is introduced as the backbone to the proposed fabrication methodology. Combined with the ability to control the refractive index of PDMS and a partial curing technique that bonds subsequent layers, a bottom-up layer-by-layer fabrication process is proposed and described in detail

Economic Well-Being of Farm Households

Farm subsidy programs were introduced in the 1930s largely due to concern for chronically low, and highly variable, incomes of US farm households. Today commodity-based support programs are still prominent, though income and wealth of the average farm household now exceed that of the average nonfarm households - by a large margin. Farm income continues to be highly variable, but the small set of farm households most at risk for income variability - because farm income represents more than one-third of household income - are those operating large farms. And they have substantial net worth, which cushions uncertain farm income.Farm households, household income, household wealth, household net worth, living expenses, joint income-wealth indicator, economic well-being, financial well-being, Off-farm employment, Income variability, ERS, USDA, Consumer/Household Economics,

Critical Care in the Emergency Department: An assessment of the length of stay and invasive procedures performed on critically ill ED patients

<p>Abstract</p> <p>Introduction</p> <p>Critically ill patients commonly present to the ED and require aggressive resuscitation. Patient transfer to an ICU environment in an expedient manner is considered optimal care. However, this patient population may remain in the ED for prolonged periods of time. The goal of this study is to describe the ED length of stay, and the invasive procedures performed in critically ill ED patients.</p> <p>Methods</p> <p>This is a retrospective medical record review of all patients who presented to the study center over a 1 year period. Patient demographic data, in addition to the times of ED presentation and ICU admission were recorded. Invasive procedures performed in the pre-hospital, ED and the initial 24 hours of ICU care were also recorded.</p> <p>Results</p> <p>Overall, 178 patients' required direct admission to an ICU from the ED, with a mortality rate of 21.9%. The median LOS in the ED for critically ill patients requiring ICU admission was 4.9 h (mean 6.5 h, range 1.4-28.2 h). Seventy percent of patients (125,178, 70.2%) required endotracheal intubation with the majority (118/125, 94.4%) being performed in the ED (80/125, 64.0%) or the prehospital setting (38/125, 30.4%). Central venous access was obtained in 56/178 patients (31.5%), with 17.9% (10/56) completed in the ED. Similarly, arterial catheters were inserted in 99/178 patients (55.6%) with 14.1% (14/99) inserted in the ED.</p> <p>Conclusion</p> <p>Critically ill patients are managed in the emergency department for a significant length of time. Although the majority of airway intervention occurs in the prehospital setting and ED, relatively few patients undergo invasive procedures while in the emergency department.</p

Collider Signatures from the Brane World

We discuss some collider signatures of the brane world. In addition to the usual bulk (closed string) fields and brane (open string) fields in the Type I string picture, there are closed string fields, namely, twisted modes, which are not confined on the branes but nonetheless are localized in the extra compactified dimensions. While the coupling of the Standard Model (brane) fields with a bulk mode (such as the graviton) is suppressed by powers of the Planck mass, their coupling to a twisted mode is suppressed only by powers of the string scale M_s, which can be as low as a few TeV. This means these localized twisted fields can have important observable effects in the TeV range, including resonances in dijet invariant mass distributions in \bar p p, pp \to jets + X. Given the current lower bound on the fundamental higher-dimensional Planck scale, the experimental effects of these twisted fields may turn out to be larger than the effects of virtual and real KK gravity modes. The collider signatures of anomalous U(1) gauge symmetries as well as other phenomenological implications of the brane world are also discussed.Comment: Published version (paper shortened to satisfy the requirements of Phys. Lett. B; see version 1 for original-length paper

Motion in the north Iceland volcanic rift zone accommodated by bookshelf faulting

Along mid-ocean ridges the extending crust is segmented1 on length scales of 10–1,000 km. Where rift segments are offset from one another, motion between segments is accommodated by transform faults that are oriented orthogonally to the main rift axis. Where segments overlap, non-transform offsets with a variety of geometries2 accommodate shear motions. Here we use micro-seismic data to analyse the geometries of faults at two overlapping rift segments exposed on land in north Iceland. Between the rift segments, we identify a series of faults that are aligned sub-parallel to the orientation of the main rift. These faults slip through left-lateral strike-slip motion. Yet, movement between the overlapping rift segments is through right-lateral motion. Together, these motions induce a clockwise rotation of the faults and intervening crustal blocks in a motion that is consistent with a bookshelf-faulting mechanism, named after its resemblance to a tilting row of books on a shelf3. The faults probably reactivated existing crustal weaknesses, such as dyke intrusions, that were originally oriented parallel to the main rift and have since rotated about 15° clockwise. Reactivation of pre-existing, rift-parallel weaknesses contrasts with typical mid-ocean ridge transform faults and is an important illustration of a non-transform offset accommodating shear motion between overlapping rift segments

Anisotropic higher derivative gravity and inflationary universe

Stability analysis of the Kantowski-Sachs type universe in pure higher derivative gravity theory is studied in details. The non-redundant generalized Friedmann equation of the system is derived by introducing a reduced one dimensional generalized KS type action. This method greatly reduces the labor in deriving field equations of any complicate models. Existence and stability of inflationary solution in the presence of higher derivative terms are also studied in details. Implications to the choice of physical theories are discussed in details in this paper.Comment: 9 page

Adaptive Control Allocation for Powered Descent Vehicles

The following work details a study into real-time failure adaptive control allocation method for powered descent vehicle systems. The motivation for this work is to enable future human and robotic missions utilizing a powered descent system to tolerate engine failures in flight without the loss of crew or assets. This study is conducted using a six degree-of-freedom trajectory simulation of a PDV (Powered Descent Vehicle) experiencing either a loss of thrust or an engine stuck full on failure scenario. Sequential least squares in the frequency domain is used on-board to process inertial measurement unit (IMU) data and generate an estimate of the PDV plant model, which is then fed to the guidance and control system. Data used by the sequential least squares method is generated from an in-flight maneuver. The work herein focuses on determining a maneuver that is least impactful to the PDV trajectory and enables a suitable plant model estimate. A 1.5-second-long maneuver with an amplitude of 5 percent throttle is determined to provide suitable data for the sequential least squares method to estimate a plant model. A PDV implementing this method can adapt to a single engine failure and continue to reach its touchdown conditions