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Solid state semiconductor based neutron detectors have the potential to be energy efficient and compact, making them suitable for applications where low power consumption and size constraints are important considerations. Herein, neutron detection devices based on PIN structures consisting of BGaN/GaN superlattice (SL) are demonstrated. These SL structures enable to incorporate significant boron (B) content and achieve good crystalline quality epilayers crucial for better neutron detection. Further, by leveraging the built‐in electric field generated by the PIN structure, these devices can be operated without any applied bias, simplifying overall operation and enabling a more compact size system for detection. Their performance is evaluated by measuring real‐time current response under neutron irradiation (IN) and without it (ID). The neutron induced current density (ΔJ = JN − JD) is determined, reaching an impressive value of 0.67 pA cm−2 (two times JD) under thermal neutron flux of 1.2 × 104 n cm−2 s−1 without biasing, demonstrating their self‐powered capability. They exhibit a linear response to varying thermal neutron flux levels. Additionally, the detectors successfully detect low thermal neutron fluxes down to 300 n cm−2 s−1, showcasing their potential for diverse applications, including in low neutron environments, screening nuclear warheads, and preventing illegal trafficking of radiological materials. [ABSTRACT FROM AUTHOR]

The growth of hexagonal boron nitride (h‐BN) and van der Waals (vdW) epitaxy of blue multi‐quantum well (MQW) GaN‐based LED heterostructures on 6‐inch sapphire substrates using metal‐organic chemical vapour deposition (MOCVD) is demonstrated. Challenges associated with the growth of large surface h‐BN and the subsequent vdW epitaxy of GaN‐based LED heterostructures are discussed. To overcome these challenges, the spatial uniformity is controlled of the growth temperature, optimizes the slope of temperature variations during the growth and cooling process, and manages the surface temperature during switching of gas flows. With these adaptations, high quality GaN‐based LED heterostructures are grown on h‐BN without any spontaneous delamination. The GaN‐based LED devices are then fabricated on a 6‐inch sapphire wafer, which are lifted off as a membrane and transferred to a flexible copper support. These GaN‐based LED devices emitt bright blue illumination with an electroluminescence peak at 437 nm. This scaling up of growth, lift‐off, and transfer can lead to the commercialization of GaN‐based LEDs on h‐BN template on 6‐inch sapphire substrates, with a process compatible with current modern equipment for the fabrication of LEDs and electronic devices. [ABSTRACT FROM AUTHOR]

Several technological challenges have prevented GaN‐based micro‐LEDs from finding application in mass market displays, despite their unique properties such as very high brightness and the very fast response time of GaN‐based materials. The primary challenges are the cost and complexity of lift‐off and transfer of LEDs from sapphire substrates to suitable supports as well as the lowered performance of tiny micro‐LEDs caused by chemical etching that defines individual LEDs. Herein, this work reports demonstration of a complete process that solves these challenges with epitaxy and cleanroom technologies that are commercially available. The process begins with van der Waals epitaxy of 2D h‐BN on silica masks with square, triangular and hexagonal patterns on sapphire substrates which define the micro‐LED regions. Then selective area growth of MQW LED heterostructures, with ultra smooth crystalline sidewalls, down to ultra tiny size of 1.4 µm is performed. Because of the lack of vertical chemical bonds in the h‐BN layer, simple mechanical lift‐off and transfer is performed on an array of LEDs heterostructures down to size of 8 µm. Finally, transparent ITO p‐contacts are deposited on LEDs with uniform lift‐off, resulting in high brightness LEDs. [ABSTRACT FROM AUTHOR]

Examination of the 1979 income status of 1975-80 in-migrants, out-migrants, and nonmigrants in 223 nonmetropolitan low-income counties in the South indicates that migration had very little influence on income, whether subpopulation mean incomes or aggregate dollar amounts. Contains 42 references. (SV)

We have previously surveyed a panel of 508 physicians from around the world about which biomarkers would be relevant if obtained in a very short time frame, corresponding to emergency situations (life-threatening or not). The biomarkers that emerged from this study were markers of cardiovascular disease: troponin, D-dimers, and brain natriuretic peptide (BNP). Cardiovascular disease is a group of disorders affecting the heart and blood vessels. At the intersection of medicine, basic research and engineering, biosensors that address the need for rapid biological analysis could find a place of choice in the hospital or primary care ecosystem. Rapid, reliable, and inexpensive analysis with a multi-marker approach, including machine learning analysis for patient risk analysis, could meet the demand of medical teams. The objective of this opinion review, proposed by a multidisciplinary team of experts (physicians, biologists, market access experts, and engineers), is to present cases where a rapid biological response is indeed valuable, to provide a short overview of current biosensor technologies for cardiac biomarkers designed for a short result time, and to discuss existing market access issues. [ABSTRACT FROM AUTHOR]

The ability for quick multidirectional accelerations is crucial for athletic performance in team and racquet sports. So far, there has been little research dedicated to different initial step patterns usually applied by players. Therefore, the present study investigated the kinematic characteristics and effectiveness of the following step patterns: Jab Step (JS), Pivot Step (PS), Gravity Step (GS) and Counter Step (CS). Twenty-two male competitive team and racquet sport athletes completed maximum lateral accelerations utilizing the step patterns. Following familiarization with each step pattern, three 5 m sprints (5 m STs) into both directions (left & right) were completed. Sprint times, the translation of the center of mass (CoM) and joint angles were obtained using three-dimensional motion analysis. 5 m STs of the CS were faster compared to the GS and PS for both directions. A detailed distance-time analysis revealed that for shorter distances only the JS was faster than the GS. Regarding the sequence in which the maximum angular velocities (max. w → ) in the hip, the knee, and the ankle were reached during the push off, there was a proximal-to-distal sequence for the JS and the CS, but a distal-to proximal sequence for the GS and the PS. The results reveal that the JS and the CS are superior for accelerations towards the lateral direction. Specifically, they indicate that the JS is more suitable for covering very short distances and the CS is superior for covering further distances. In addition, the distal-to-proximal sequence of max. w → during the push-off in the GS and the PS might indicate lower kinematic efficiency. [ABSTRACT FROM AUTHOR]

In this paper we return to an issue often discussed in the literature regarding the relationship between highway expansion and population change. Typically it simply is assumed that this relationship is well established and understood. We argue, following a thorough review of the relevant literature, that the notion that highway expansion leads to increased population growth in the vicinity of the improved infrastructure finds only weak and often conflicting support. Using data on all major highway expansions in Wisconsin covering the period from the late-1960s through the 1990s from the Wisconsin Department of Transportation (WisDOT), and census data at the minor civil division (MCD) level covering the period 1970 to 2000, we deploy the analytical tools of geographic information system (GIS) software, and theory from the expanding literature in spatial analysis and modeling, to take a fresh look at this relationship. Our analysis reveals that there is a modest relationship between highway expansion and population growth among MCDs within 10-20 miles of the expanded major highway. The causal structure, however, is complex. Our starting hypothesis argues that population growth precedes highway expansion as frequently as population growth results from highway expansion, but the data show otherwise. The dominant causal influence appears to flow from highway expansion to population growth.

Altitude control enables balloons to perform atmospheric soundings, avoid restricted airspace, and exercise rudimentary navigational control. Reversible altitude control, which does not expend lift gas or ballast, is particularly attractive because long-duration flights can be achieved. Methods of reversible altitude control, including air ballast and mechanical compression, are compared. A new system, described here as differential expansion, is ideally suited to near-neutral density operation and has many advantages over existing altitude control systems including cost, ease of construction, and altitude range.

The Idolatrous Eye: Iconoclasm & Theater in Early Modern England. By MICHAEL O'CONNELL. New York and Oxford: Oxford University Press. 2000. ix+198 pp. 45 £. ISBN 0-19-513205-X. In this learned [...]

The incongruency of diurnally varying resources essential to plants may detrimentally affect plants early in their development as indicated by reduced water use efficiency and carbon gain. Typical diurnal patterns of light and C[O.sub.2] availability in a midsized temperate herbaceous or forest gap were simulated in specially designed growth chambers. A sinusoidally varying C[O.sub.2] treatment (400 ppm minimum, 800 ppm maximum) approximated the diurnal cycle of C[O.sub.2] at the soil surface, while a steady-state C[O.sub.2] treatment (600 ppm) with the same average C[O.sub.2] concentration provided a control. Crossed with these two C[O.sub.2] treatments were two light regimes, one with 3 h of high light (850 [[micro]mol] [multiplied by] [m.sup.-2] [multiplied by] [s.sup.-1]) in the morning (west side of a gap), and the other with 3 h of high light in the afternoon (east side). All treatments received baseline low light (55 [[micro]mol] [multiplied by] [m.sup.-2] [multiplied by] [s.sup.-1]) for 14 h during the day. Rumex crispus was selected as a model species because of its rosette leaves, which grow close to the ground where diurnal C[O.sub.2] variation is greatest. The relative timing of diurnal variations in light and C[O.sub.2] significantly affected seedling water use efficiency, carbon gain, and morphology. Total biomass, photosynthetic rates, daily integrated carbon, water use efficiency, and leaf area were enhanced by morning exposure to high light. Seedlings that were exposed to peak values of light and C[O.sub.2] incongruently, i.e., those plants receiving intense afternoon light with diurnally varying C[O.sub.2], were detrimentally affected relative to control plants receiving intense afternoon light with steady-state C[O.sub.2]. The results of this experiment indicate that the incongruent availability of required resources - such as light and C[O.sub.2] - can detrimentally affect performance relative to when resources are congruent. These contrasting resource regimes can occur on the east and west side of gaps. Key words: incongruency of resources; diurnal cycles; gaps; Polygonaceae; Rumex crispus; photosynthesis; water use efficiency.

The first epic simile in John Milton's 'Paradise Lost' compares the size of Satan, who is floating on a burning lake, to assorted large creatures of classical mythology. General words are used, but so is 'rood.' This key word in the passage is not seen elsewhere in Milton's poetry. 'The Oxford English Dictionary' defines it as a measurement unit for land meaning a quarter-acre. Another meaning for the word, one more used in the 16th and 17th centuries, is 'cross.' Given the war in heaven, crosses floating around Satan become symbols of Christ executing victory. Satan is then a parody of Christ. Milton may also have thought of trappings of high church ceremony ending up in hell.

The van der Waals (vdW) epitaxy of three-dimensional (3D) device structures on two-dimensional (2D) layers is particularly interesting for III-nitrides because it may relax lattice matching and thermal mismatch requirements and can allow convenient lift-off of epilayers and optoelectronic devices. In this article, we report the vdW epitaxy of 3D GaN/AlGaN on 2D h-BN grown on a-, c-, and m-plane sapphire substrates via metal–organic chemical vapor phase epitaxy. First, we study 2D h-BN layers grown on a-, c-, and m-plane sapphire to demonstrate the effect of the substrate on h-BN growth and h-BN alignment. We find that h-BN can align itself to its preferred c-axis with a slight misorientation on the m-plane sapphire substrate. However, the differences in crystallographic orientation, thermal expansion coefficient, and surface energy of differently oriented sapphire substrates strongly influence the surface morphology (good for a- and c-planes) and the adhesion of h-BN layers (lift-off only possible for the c-plane). Second, the vdW growth of 3D GaN/AlGaN on 2D h-BN grown on a-, c-, and m-planes of sapphire was investigated. High-resolution X-ray diffraction (HR-XRD) 2θ–ω scan and selected area electron diffraction pattern were used to demonstrate the misorientation of GaN/AlGaN grown on 2D h-BN/m-plane sapphire compared to polar GaN grown on 2D h-BN/a- and c-plane sapphire. It was found that the morphology and crystalline quality of GaN/AlGaN are directly affected by the 2D h-BN layers. These results provide initial insight into the impact of substrate orientation, thereby acting as a guide for the potential design of III-nitride/h-BN vdW epitaxy seeking to use nonpolar or semipolar planes of sapphire for optoelectronic devices such as light-emitting diodes (LEDs), high-power electronics, and detectors. [ABSTRACT FROM AUTHOR]

GaN, with its wide bandgap of 3.4 eV, has emerged as an efficient material for designing high-efficiency betavoltaic batteries. An important part of designing efficient betavoltaic batteries involves a good understanding of the full process, from the behavior of the nuclear material and the creation of electron-hole pairs all the way through the collection of photo-generated carriers. This paper presents a detailed model based on Monte Carlo and Silvaco for a GaN-based betavoltaic battery device, modeled after Ni-63 as an energy source. The accuracy of the model is verified by comparing it with experimental values obtained for a GaN-based p-i-n structure under scanning electron microscope illumination. [ABSTRACT FROM AUTHOR]