Spatial Coherence of a Polariton Condensate

We perform Young's double-slit experiment to study the spatial coherence properties of a two-dimensional dynamic condensate of semiconductor microcavity polaritons. The coherence length of the system is measured as a function of the pump rate, which confirms a spontaneous buildup of macroscopic coherence in the condensed phase. An independent measurement reveals that the position and momentum uncertainty product of the condensate is close to the Heisenberg limit. An experimental realization of such a minimum uncertainty wave packet of the polariton condensate opens a door to coherent matter-wave phenomena such as Josephson oscillation, superfluidity, and solitons in solid state condensate systems

Double-layer shocks in a magnetized quantum plasma

The formation of small but finite amplitude electrostatic shocks in the propagation of quantum ion-acoustic waves (QIAWs) obliquely to an external magnetic field is reported in a quantum electron-positron-ion (e-p-i) plasma. Such shocks are seen to have double-layer (DL) structures composed of the compressive and accompanying rarefactive slow-wave fronts. Existence of such DL shocks depends critically on the quantum coupling parameter $H$ associated with the Bohm potential and the positron to electron density ratio $\delta$. The profiles may, however, steepen initially and reach a steady state with a number of solitary waves in front of the shocks. Such novel DL shocks could be a good candidate for particle acceleration in intense laser-solid density plasma interaction experiments as well as in compact astrophysical objects, e.g., magnetized white dwarfs.Comment: 4 pages, 1 figure (to appear in Physical Review E

Metropolitan water supply allocation and operation

In metropolitan areas, water is supplied to consumers from one or more sources through separate but adjacent systems of facilities commonly owned and operated by municipal governments. Allocation of production and distribution is determined by the demand contained within municipal boundaries rather than on the basis of regional efficiency. Some systems may have more capacity than required to meet their needs, while others have insufficient capacity; and the excess capacity of one system could be used to augment the system that lacks capacity and thereby improve the overall efficiency of utilization. When viewed as a regional allocation problem, then, the challenge is to minimize the total cost of providing potable water with a given set of facilities (in the economic short-run sense). This can be accomplished by equating the marginal costs of production plus transportation among all interconnected systems of the region, while meeting, as constraints, water demands and capacity limitations. Production cost and transportation (distribution) cost functions were determined for selected water supply systems (or subsystems) in the Chicago area. Production cost and transportation cost functions were determined econometrically and, for transportation costs, technologically using a geometric programming procedure. The resulting cost functions were then used in an example problem to illustrate the utility of the proposed methodology for allocation and operation.U.S. Geological SurveyU.S. Department of the InteriorOpe

Mechanism of non-classical light emission from acoustically populated (311)A GaAs quantum wires

We employ surface acoustic waves (SAWs) to control the transfer of photo-generated carriers between interconnected quantum wells and quantum wires (QWRs) grown on pre-patterned (311)A GaAs substrates. Optical studies, carried out under remote acoustic excitation of a single QWR, have shown sharp photoluminescence lines and antibunched photons with tunable emission energy. These features are attributed to recombination of acoustically transported carriers in potential inhomogeneities within the wire. The origin of the photon antibunching is discussed in terms of a 'bottleneck' in the number of carriers trapped in the QWR, which restricts the number of recombination events per SAW cycle. We propose a model for antibunching based on the trapping of carriers induced by the SAW piezoelectric field in states at the interface between the GaAs QWR and the AlGaAs barriers. Non-classical light is emitted during the subsequent release of the trapped carriers into the recombination centers within the wire. The spatial distribution of the emitting recombination centers is estimated using time-resolved measurements

Carnivorous Spadefoot (Spea bombifrons Cope) Tadpoles and Fairy Shrimp in Western Iowa

Amphibian larval polymorphisms, rarely found in the Midwest, are more common in arid western regions. We have discovered that Plains spadefoot toad, Spea bombifrons Cope, tadpoles occur as carnivorous and omnivorous morphological forms in flooded soybean and corn fields on the Missouri River flood plain of western Iowa. Carnivores have longer snouts, larger beaks with an upper cusp and lower notch, shorter intestines with fewer loops than the omnivores, and they feed on fairy shrimp. A similar polymorphism in Spea multiplicata Cope enhances survival in the desert because the carnivore develops faster after consuming fairy shrimp and is able to metamorphose in rapidly drying ponds. However, the omnivore develops slower in deeper ponds, stores more fat and has better postmetamorphic success. Fairy shrimp ingestion triggers development of the S. multiplicata carnivores, but whether this is also true for S. bomifrons remains to be seen. Distributions and abundance of both carnivorous S. bombifrons tadpoles and fairy shrimp need to be determined across the Great Plains and in Iowa

Quantized Dispersion of Two-Dimensional Magnetoplasmons Detected by Photoconductivity Spectroscopy

We find that the long-wavelength magnetoplasmon, resistively detected by photoconductivity spectroscopy in high-mobility two-dimensional electron systems, deviates from its well-known semiclassical nature as uncovered in conventional absorption experiments. A clear filling-factor dependent plateau-type dispersion is observed that reveals a so far unknown relation between the magnetoplasmon and the quantum Hall effect.Comment: 5 pages, 3 figure

Identifying and accounting for the Coriolis Effect in satellite NO2 observations and emission estimates

Recent developments in atmospheric remote sensing from satellites have made it possible to resolve daily emission plumes from industrial point sources, around the globe. Wind rotation aggregation coupled with statistical fitting is commonly used to extract emission estimates from these observations. These methods are used here to investigate how the Coriolis Effect influences the trajectory of observed emission plumes, and to assess the impact of this influence on satellite derived emission estimates. Of the 17 industrial sites investigated, nine showed the expected curvature for the hemisphere they reside in. Five showed no or negligible curvature, and two showed opposing or unusual curvature. The sites which showed conflicting curvature all reside in topographically diverse regions, where strong meso-gamma scale (2&ndash;20 km) turbulence dominates over larger synoptic circulation patterns. For high curvature cases the assumption that the wind-rotated plume aggregate is symmetrically distributed across the downwind axis breaks down, which impairs the quality of statistical fitting procedures. Using NOx emissions from Matimba power station as a test case, not compensating for Coriolis curvature resulted in an10 underestimation of &sim; 9 % on average for years 2018 to 2021. This study is the first formal observation of the Coriolis Effect and its influence on satellite observed emission plumes, and highlight both the variability of emission calculation methods and the need for a standardised scheme for this data to act as evidence for regulators.</p

Peningkatan Hasil Belajar Siswa pada Pembelajaran Kpk dan Fpb di Sdn 04 Delta Pawan Ketapang

. This study about learning and FPB and KPK on Elementary School 04 Delta Pawan Ketapang. The purpose of this study to determine the increase in student learning outcomes in mathematics learning by registering in fourth grade Elementary School District 04 Delta Pawan Ketapang. Methods This study uses descriptive method. This research is a form of classroom action research. Techniques of data collection using direct observation and measurement, while the means of collecting data using observation sheets and achievement test. The results show the ability of teachers to plan learning in the first cycle of the score 2 to score 3 in cycle 2. The ability of teachers to implement the learning in the first cycle of an average score of 2.64 to 3.97 in cycle 2. Increased student learning outcomes, in cycle 1 the average value of 65.59 into 86.06 in cycle 2. Students who achieve a passing grade on cycle 1 of 7 people (41.12 %), in cycle 2 as many as 14 people (82.35 %) , with an increase of 41.28 %