14.6-GHz LiNbO/sub 3/ microdisk photonic self-homodyne RF receiver

Nonlinear optical modulation combined with simultaneous photonic and RF resonance in an LiNbO/sub 3/ microdisk modulator is used to create a self-homodyne photonic RF receiver. Carrier and sidebands are mixed in the optical domain, and the modulated optical signal is detected using a photodetector. The photodetector has a bandwidth matched to the baseband signal. It filters out the high-frequency components and generates the baseband photocurrent. Receiver operation is demonstrated by demodulating up to 100-Mb/s digital data from a 14.6-GHz carrier frequency without any high-speed electronic components. A bit error rate of 10/sup -9/ is measured for 10-Mb/s downconverted digital data at -15-dBm received RF power. Preliminary results of employing this photonic RF receiver in a short-distance Ku-band wireless link demonstrate the potential of using high-quality optical microresonators in RF receiver applications

Effects of Dietary Energy Density and Intake on Maintenance Energy Requirements in Beef Cows

A variety of issues concerning the sustainability of beef production systems, including alternative land use decisions and liquidation in cow inventory, have magnified the need to enhance system efficiency. One approach to increasing production efficiency is through the intensification of cow-calf systems. In intensified systems cows will be housed in a controlled environment (i.e. drylot) for at least a portion of their reproductive cycle, subsequently offering the opportunity to develop nutritional manipulation strategies to optimize cow efficiency. An experiment was conducted to analyze the effects of dietary energy density and intake on maintenance energy requirements in beef cows. In a 2 x 2 factorial treatment arrangement, thirty-two crossbred cows were fed either a high- (H, 2.54 Mcal ME/kg) or a low-energy (L, 1.96 Mcal ME/kg) diet at one of two levels of intake (80; 80% NRC NE requirements, 120; 120% NRC NE requirements). Several methods using empirical equations were used to estimate body energy on d 0 and 56 as a proxy for RE. HE was calculated as the difference between ME and RE. Body weight gain tended to be greater (P = 0.08) in H than L, but was not different (P = 0.12) between 120 than 80. Retained energy tended to be greater (P ≤ 0.10) in H than L and greater (P ≤ 0.08) in 120 than 80. Heat energy per EBW^0.75 was greater (P 0.22) or level of intake (P > 0.56). Feed requirement for maintenance was calculated to be 92.54 and 168.06 kcal ME/EBW^0.75 for H and L, respectively. Fasting heat production was estimated to be 54.60 and 74.78 kcal/EBW^0.75 for H and L, respectively. Overall, increasing dietary energy density resulted in a decrease in maintenance requirements of approximately 28% and intake restriction decreased HE by approximately 28%, with no interaction, suggesting additive effects. Limit feeding high-energy diets to beef cows has the potential to increase the efficiency of production and land use in U.S. cow-calf systems

ENHANCING ENERGY EFFICIENCY OF INTENSIFIED COW-CALF PRODUCTION SYSTEMS THROUGH OPTIMAL FEEDING STRATEGIES

A series of experiments was designed to aid in developing optimal solutions for intensive cow-calf production. In the first experiment, we studied potential system limitations regarding inclusion and intake of grain and their effects on risk of digestive upset. Ruminal pH declined rapidly when concentrate diets were fed at high intake levels, but the minimal risk of acidosis observed at high intakes was mitigated through intake restriction. Next, we quantified interactions between dietary energy density and intake on energy digestibility to more accurately predict energy supplies. When high-energy diets were limit-fed to maintenance intake, more complete digestion leads to under estimation of DE intake. In the third experiment, we measured effects of dietary energy density and intake on apparent energy requirements. Divergence between observed and predicted energy retention was observed, suggesting that increasing energy density and restricting intake improved energy metabolism. Finally, in a study involving two experiments, we determined the effects of intake restriction on mass and metabolism of metabolically active organs to determine their role in a cow’s ability to adapt under periods of energy deficiency. Dietary energy restriction reduced the mass of metabolically active organs. Overall, limit-feeding high-energy diets to beef cows appears to provide opportunities for increased efficiency of land and feed energy use, with minimal risks to animal health. Previous nutrition models neglect to account for effects of intake restriction on energy metabolism, causing an overestimation of feed requirements for intensively-managed beef cows

Direct electrical-to-optical conversion and light modulation in micro whispering-gallery-mode resonators

Techniques for directly converting an electrical signal into an optical signal by using a whispering gallery mode optical resonator formed of a dielectric material that allows for direct modulation of optical absorption by the electrical signal

Enantioselective dearomative [3 + 2] cycloadditions of indoles with azomethine ylides derived from alanine imino esters

Catalytic, enantioselective [3 + 2] cycloadditions of azomethine ylides derived from alanine imino esters with 3-nitroindoles are reported. The dearomative cycloaddition reactions occur in the presence of a catalyst generated in situfrom Cu(OTf)2 and (R)-Difluorphos to form exo′-pyrroloindoline cycloadducts and establish four contiguous stereogenic centers, two of which are fully substituted. The exo′-pyrroloindoline products are formed in moderate-to-good yields (39–85%) with high diastereoselectivities (up to 98:1:1 dr) and enantioselectivities (up to 96% ee)

Photovoltaics and the National Park Service : an institutional analysis

On cover: Energy Laboratory Utility Systems Program.This paper is one of a series resulting from institutional analysis of photovoltaic (PV) acceptance. The case reported here involves the acceptance of PV by the National Park Service. As part of the Department of the Interior, the NPS is an agency exemplifying the federal non- defense sector. A modified.organizational set model which concentrates on exchanges between and among organizational set elements, was used in this study. Though initially the inquiry from the Department of Energy to NPS to do a PV field test at a NPS site was considered the perturba- tion prompter, preliminary exploration showed an earlier perturbation-- the need for energy conservation. The differentiations which followed on this perturbation provided an envelope within which PV was subsequently considered and accepted. This envelope made an otherwise incompre- hensible innovation more comprehensible by its association with an ongoing routine of acceptance of energy conservation initiatives. The critical role of the NPS's Denver Service Center as an innovation mediator is described. The DSC serves such a function routinely for the NPS, a reality which greatly enhances the likelihood of acceptance of innovations disseminated through this institutional entity

A simultaneous preference reporting methodology applied to the Nebraska agricultural community

Prepared for the United States Dept. of Energy under Contract no. EX-76-A-01-2295, Task order 37.One of a series of publications which are part of the institutional analysis research conducted under the Department of Energy's Photovoltaic (PV) Program, this paper describes the Simultaneous Preference Reporting Methodology and reports the results of collecting data in conjunction with an agricultural field test of PV in rlead, Nebraska. The authors find that in the Nebraska Agricultural Community, PV is an undifferentiated innovation. They also conclude that the Simultaneous Preference Reporting Methodology is a promising diagnostic and predictive tool regarding the acceptance of institutional innovation

Visual deficits in anisometropia

AbstractAmblyopia is usually associated with the presence of anisometropia, strabismus or both early in life. We set out to explore quantitative relationships between the degree of anisometropia and the loss of visual function, and to examine how the presence of strabismus affects visual function in observers with anisometropia. We measured optotype acuity, Pelli-Robson contrast sensitivity and stereoacuity in 84 persons with anisometropia and compared their results with those of 27 persons with high bilateral refractive error (isoametropia) and 101 persons with both strabismus and anisometropia. All subjects participated in a large-scale study of amblyopia (McKee et al., 2003). We found no consistent visual abnormalities in the strong eye, and therefore report only on vision in the weaker, defined as the eye with lower acuity. LogMAR acuity falls off markedly with increasing anisometropia in non-strabismic anisometropes, while contrast sensitivity is much less affected. Acuity degrades rapidly with increases in both hyperopic and myopic anisometropia, but the risk of amblyopia is about twice as great in hyperopic than myopic anisometropes of comparable refractive imbalance. For a given degree of refractive imbalance, strabismic anisometropes perform considerably worse than anisometropes without strabismus – visual acuity for strabismics was on average 2.5 times worse than for non-strabismics with similar anisometropia. For observers with equal refractive error in the two eyes there is very little change in acuity or sensitivity with increasing (bilateral) refractive error except for one extreme individual (bilaterally refractive error of –15D). Most pure anisometropes with interocular differences less than 4D retain some stereopsis, and the degree is correlated with the acuity of the weak eye. We conclude that even modest interocular differences in refractive error can influence visual function