Modeling Light Trapping in Nanostructured Solar Cells

The integration of nanophotonic and plasmonic structures with solar cells offers the ability to control and confine light in nanoscale dimensions. These nanostructures can be used to couple incident sunlight into both localized and guided modes, enhancing absorption while reducing the quantity of material. Here we use electromagnetic modeling to study the resonances in a solar cell containing both plasmonic metal back contacts and nanostructured semiconductor top contacts, identify the local and guided modes contributing to enhanced absorption, and optimize the design. We then study the role of the different interfaces and show that Al is a viable plasmonic back contact material

Medievalism, Modernity and Memory: Cropthorne Church, 1892–1910

Recorded in the Domesday Survey for Worcestershire (1086), the Church of St. Michael in Cropthorne, Worcestershire is an ancient building with a rich history. Drawing on surviving manuscript and visual sources, this article examines the repairs, restoration and refurbishments made to the interior of St. Michael’s between 1890 and 1910. This was a period in which the ownership of the village shifted from the Anglican Church to private patronage and a time which witnessed many changes to the fabric of the building; notably the extensive refurbishments carried out to the chancel in 1894 by Francis Holland, the Lord of the Manor and the restoration of the rest of Cropthorne church which took more than eighteen years to complete. Highlighting the significance of the Church in rural areas as a place for personal and community memory, this article will consider how these changes to a sacred space used for communal worship were linked to the social changes experienced by the rural community that worshipped within it: moving beyond a purely architectural survey of the building, it will identify the agents of these changes; the processes involved in accomplishing them; and, responses to these alterations. Consequently, the alterations and additions to the interior of St. Michael’s made at the instigation and expense both of the Holland Family of Cropthorne Court and the people of Cropthorne will be analyzed in the context of the changing religious, technological, social, economic and political conditions of the period, which include the effects of the Agricultural Depression and the devastating impact of war

Spatial and Temporal Distribution of Dredged Sediments Disposed at the Pensacola, Florida, Ocean Dredged Material Disposal Site Using Naturally Occurring Gamma Radiation

The fate and effects of large volumes of dredged sediments disposed at offshore disposal sites are of particular interest to the federal and state agencies responsible for its management. During the period from Jan. to April 1990, 3. 7 million m3 of dredged sediments were disposed of at the Pensacola, FL, Ocean Dredged Material Disposal Site (ODMDS). From May 1990 to Oct. 1993, the dispersal of dredged sediments in the area surrounding the disposal site was studied using bathymetry, sediment particle size distribution, and the differential abundance of naturally occurring gamma radiation emitters in dredged sediments and native seafloor sediments. Gamma radiation measurements in the 0.4- to 3.0-MeV energy range, made in May 1990, showed that disposal activities at the Pensacola site resulted in the accumulation of fine (silts and clays) dredged sediments throughout the 91-km2 survey area. The average proportion of fine-grained sediment particles (silts and clays) in surface sediments outside the boundaries of the designated disposal site more than doubled after disposal. By the end of the 3-yr study period in 1993, the bulk of the fine-grained dredged sediment had been transported away from the area surrounding the ODMDS. Gamma radiation measurements were able to detect the presence of dredged sediments in the disposal zone and in several areas outside the disposal site boundaries

Plasmonic Nanostructure Design for Efficient Light Coupling into Solar Cells

We demonstrate that subwavelength scatterers can couple sunlight into guided modes in thin film Si and GaAs plasmonic solar cells whose back interface is coated with a corrugated metal film. Using numerical simulations, we find that incoupling of sunlight is remarkably insensitive to incident angle, and that the spectral features of the coupling efficiency originate from several different resonant phenomena. The incoupling cross section can be spectrally tuned and enhanced through modification of the scatterer shape, semiconductor film thickness, and materials choice. We demonstrate that, for example, a single 100 nm wide groove under a 200 nm Si thin film can enhance absorption by a factor of 2.5 over a 10 μm area for the portion of the solar spectrum near the Si band gap. These findings show promise for the design of ultrathin solar cells that exhibit enhanced absorption

Equity of Inpatient Health Care in Rural Tanzania:\ud A Population- and Facility-Based Survey

To explore the equity of utilization of inpatient health care at rural Tanzanian health centers through the use of a short wealth questionnaire.Methods: Patients admitted to four rural health centers in the Kigoma Region of Tanzania from May 2008 to May 2009 were surveyed about their illness, asset ownership and demographics. Principal component analysis was used to compare the wealth of the inpatients to the wealth of the region’s general population, using data from a previous population-based survey. Among inpatients, 15.3% were characterized as the most poor, 19.6% were characterized as very poor, 16.5% were characterized as poor, 18.9% were characterized as less poor, and 29.7% were characterized as the least poor. The wealth distribution of all inpatients (p < 0.0001), obstetric inpatients (p < 0.0001), other inpatients (p < 0.0001), and fee-exempt inpatients (p < 0.001) were significantly different than the wealth distribution in the community population, with poorer patients underrepresented among inpatients. The wealth distribution of pediatric inpatients (p = 0.2242) did not significantly differ from the population at large. The findings indicated that while current Tanzanian health financing policies may have improved access to health care for children under five, additional policies are needed to further close the equity gap, especially for obstetric inpatients.\u

Spin interference effects in ring conductors subject to Rashba coupling

Quantum interference effects in rings provide suitable means for controlling spin at mesoscopic scales. Here we apply such control mechanisms to coherent spin-dependent transport in one- and two-dimensional rings subject to Rashba spin-orbit coupling. We first study the spin-induced modulation of unpolarized currents as a function of the Rashba coupling strength. The results suggest the possibility of all-electrical spintronic devices. Moreover, we find signatures of Berry phases in the conductance previously unnoticed. Second, we show that the polarization direction of initially polarized, transmitted spins can be tuned via an additional small magnetic control flux. In particular, this enables to precisely reverse the polarization direction at half a flux quantum. We present full numerical calculations for realistic two-dimensional ballistic microstructures and explain our findings in a simple analytical model for one-dimensional rings.Comment: 8 pages, 5 figures. Submitted to Phys. Rev. B, final versio

Coherent transport through graphene nanoribbons in the presence of edge disorder

We simulate electron transport through graphene nanoribbons of experimentally realizable size (length L up to 2 micrometer, width W approximately 40 nm) in the presence of scattering at rough edges. Our numerical approach is based on a modular recursive Green's function technique that features sub-linear scaling with L of the computational effort. We identify the influence of the broken A-B sublattice (or chiral) symmetry and of K-K' scattering by Fourier spectroscopy of individual scattering states. For long ribbons we find Anderson-localized scattering states with a well-defined exponential decay over 10 orders of magnitude in amplitude.Comment: 8 pages, 6 Figure

Investigation of DC-8 nacelle modifications to reduce fan-compressor noise in airport communities. Part 5 - Economic implications of retrofit Technical report, May 1967 - Oct. 1969

Economic impact of modifications to DC-8 aircraft nacelles to reduce fan-compressor noise - Part

Pengaruh Jarak Tanam dan Jenis Tanaman Sela terhadap Pertumbuhan Lada Perdu Serta Hasil Tanaman Sela

Penanaman tanaman sela di antara tanaman lada perdu merupakan salah satu strategi dalam upaya mengoptimalkan pemanfaatan sumberdaya pertanian dan sekaligus dapat meningkatkan pendapatan USAhatani. Penelitian ini dilakukan di Kebun Percobaan (KP) Cahaya Negeri, Lampung Utara, mulai tahun 2010 sampai 2011. Tujuannya adalah memperoleh kombinasi jarak tanam lada perdu dengan jenis tanaman sela yang sesuai untuk mendukung pertumbuhan tanaman lada sebagai tanaman pokok serta meningkatkan hasil dan pendapataan tanaman sela. Rancangan yang digunakan adalah acak kelompok pola faktorial dua faktor dengan 3 ulangan. Faktor pertama adalah jarak tanam lada (J) yang terdiri dari 4 taraf : (J1) 1 x 3 meter, (J2) 1 x 4 meter (J3) 2 x 3 meter, dan (J4) 2 x 4 meter. Faktor kedua adalah jenis tanaman sela (S) yang terdiri dari : (S1) tanaman kacang tanah, dan (S2) tanaman sela kacang hijau. Hasil penelitian menunjukkan bahwa (1) jarak tanam lada perdu 1 x 3 m cukup sesuai untuk ditanami tanaman sela kacang tanah maupun kacang hijau karena dengan jarak tanam tersebut dapat mendukung bagi pertumbuhan vegetatif dan generatif lada serta dapat memaksimalkan hasil dan pendapatan tanaman sela, dan (2) penanaman tanaman sela kacang tanah dan kacang hijau di antara lada perdu sebaiknya dilakukan secara rotasi, kacang tanah ditanam pada fase vegetatif, sedangkan kacang hijau ditanam pada fase generatif tanaman lada. Effect of Plant Spacing and Intercrops on The Growth of Pepper and Yield of Intercrop