The Absorption of Light Passing through Deep Slits as a Function of the Length and Depth of the Slits and of the Wave Length of the Light

As indicated by Rayleigh, practically every slit is a Deep slit, and a Thin slit can be obtained only with the greatest difficulty. Rayleigh used for the latter a fine scratch in a thin silver film deposited upon glass. In the present work experiments were made with a series of slits with steel jaws, varying in depth from that of the thin safety razor blades to approximately 2.5 cm. The intensity of the transmitted light was experimentally determined as a function of the width and depth of the slits, and of the wave length of the light. For narrow slits, the narrowness depending upon the depth and wave length, practically complete polarization, with the electric vector parallel to the length of the slit, was noted, but exact measurements were deferred to a later work. On the basis of diffraction, multiple reflections, and the alteration of the ratios of the two electric vectors due to the latter, a simple theory is developed, the results of which agree well with the experimental results. The chief fact derived from the experiments is that for narrow slits the total amount of light transmitted is not, even approximately, proportional to the opening, and that therefore the use of such slits for photometric purposes will lead, unless proper corrections are made, to erroneous values for the intensity of the transmitted light

Concordant cues in faces and voices: testing the backup signal hypothesis

Information from faces and voices combines to provide multimodal signals about a person. Faces and voices may offer redundant, overlapping (backup signals), or complementary information (multiple messages). This article reports two experiments which investigated the extent to which faces and voices deliver concordant information about dimensions of fitness and quality. In Experiment 1, participants rated faces and voices on scales for masculinity/femininity, age, health, height, and weight. The results showed that people make similar judgments from faces and voices, with particularly strong correlations for masculinity/femininity, health, and height. If, as these results suggest, faces and voices constitute backup signals for various dimensions, it is hypothetically possible that people would be able to accurately match novel faces and voices for identity. However, previous investigations into novel face–voice matching offer contradictory results. In Experiment 2, participants saw a face and heard a voice and were required to decide whether the face and voice belonged to the same person. Matching accuracy was significantly above chance level, suggesting that judgments made independently from faces and voices are sufficiently similar that people can match the two. Both sets of results were analyzed using multilevel modeling and are interpreted as being consistent with the backup signal hypothesis

Entangling macroscopic diamonds at room temperature: Bounds on the continuous-spontaneous-localization parameters

A recent experiment [K. C. Lee et al., Science 334, 1253 (2011)] succeeded in detecting entanglement between two macroscopic specks of diamonds, separated by a macroscopic distance, at room temperature. This impressive results is a further confirmation of the validity of quantum theory in (at least parts of) the mesoscopic and macroscopic domain, and poses a challenge to collapse models, which predict a violation of the quantum superposition principle, which is the bigger the larger the system. We analyze the experiment in the light of such models. We will show that the bounds placed by experimental data are weaker than those coming from matter-wave interferometry and non-interferometric tests of collapse models.Comment: 7 pages, 3 figures, v2: close to the published version, LaTe

Examining the efficacy of a genotyping-by-sequencing technique for population genetic analysis of the mushroom Laccaria bicolor and evaluating whether a reference genome is necessary to assess homology

Given the diversity and ecological importance of Fungi, there is a lack of population genetic research on these organisms. The reason for this can be explained in part by their cryptic nature and difficulty in identifying genets. In addition the difficulty (relative to plants and animals) in developing molecular markers for fungal population genetics contributes to the lack of research in this area. This study examines the ability of restriction-site associated DNA (RAD) sequencing to generate SNPs in Laccaria bicolor. Eighteen samples of morphologically identified L. bicolor from the United States and Europe were selected for this project. The RAD sequencing method produced anywhere from 290 000 to more than 3 000 000 reads. Mapping these reads to the genome of L. bicolor resulted in 84 000-940 000 unique reads from individual samples. Results indicate that incorporation of non-L. bicolor taxa into the analysis resulted in a precipitous drop in shared loci among samples, suggests the potential of these methods to identify cryptic species. F-statistics were easily calculated, although an observable "noise" was detected when using the "All Loci" treatment versus filtering loci to those present in at least 50% of the individuals. The data were analyzed with tests of Hardy-Weinburg equilibrium, population genetic statistics (FIS and FST), and population structure analysis using the program Structure. The results provide encouraging feedback regarding the potential utility of these methods and their data for population genetic analysis. We were unable to draw conclusions of life history of L. bicolor populations from this dataset, given the small sample size. The results of this study indicate the potential of these methods to address population genetics and general life history questions in the Agaricales. Further research is necessary to explore the specific application of these methods in the Agaricales or other fungal groups

CliCrop: a Crop Water-Stress and Irrigation Demand Model for an Integrated Global Assessment Model Approach

http://globalchange.mit.edu/research/publications/2264This paper describes the use of the CliCrop model in the context of climate change general assessment modeling. The MIT Integrated Global System Model (IGSM) framework is a global integrated assessment modeling framework that uses emission predictions and economic outputs from the MIT Emission Prediction and Policy Analysis (EPPA) model and earth system modeling predictions from the IGSM to drive a land system component, a crop model (CliCrop) and a Water Resource System (WRS) model. The global Agriculture and Water System are dependant upon and interlinked with the global climate system. As irrigated agriculture provides 60% of grains and 40% of all crop production on 20% of global crop lands and accounts for 80% of global water consumption, it is crucial that the agricultural-water linkage be properly modeled. Crop models are used to predict future yields, irrigation demand and to understand the effect of crop and soil type on food productivity and soil fertility. In the context of an integrated global assessment, a crop water-stress and irrigation demand model must meet certain specifications that are different for other crop models; it needs to be global, fast and generic with a minimal set of inputs. This paper describes how CliCrop models the physical and biological processes of crop growth and yield production and its use within the MIT Integrated Global System Model (IGSM) framework, including the data inputs. This paper discusses the global data bases used as input to CliCrop and provides a comparison of the accuracy of CliCrop with the detailed biological-based crop model DSSAT as well as with measured crop yields over the U.S. at the country level using reanalyzed weather data. In both cases CliCrop performed well and the analysis validated its use for climate change impact assessment. We then show why correctly modeling the soil is important for irrigation demand calculation, especially in temperate areas. Finally, we discuss a method to estimate actual water withdrawal from modeled physical crop requirements using U.S. historical data.The initial funding for CliCrop was provided by USAID under a program on climate change adaptation in Niger. Further funding was provided by UN University World Institute for Development Economics Research for the Application and Development of CliCrop in Africa, the authors would like to particularly thank Prof. Finn Tarp, Prof. Channing Arndt and Dr. James Thurlow for their support. The authors also would like to thank Dr. Jawoo Koo of IFPRI for his review and contributions to the software development. The authors also gratefully acknowledge additional financial support for this work provided by the MIT Joint Program on the Science and Policy of Global Change through a consortium of industrial sponsors and Federal grants. Development of the IGSM applied in this research was supported by the U.S. Department of Energy, Office of Science (DE-FG02-94ER61937); the U.S. Environmental Protection Agency, EPRI, and other U.S. government agencies and a consortium of 40 industrial and foundation sponsors

Testing the assumptions of linear prediction analysis in normal vowels

This paper develops an improved surrogate data test to show experimental evidence, for all the simple vowels of US English, for both male and female speakers, that Gaussian linear prediction analysis, a ubiquitous technique in current speech technologies, cannot be used to extract all the dynamical structure of real speech time series. The test provides robust evidence undermining the validity of these linear techniques, supporting the assumptions of either dynamical nonlinearity and/or non-Gaussianity common to more recent, complex, efforts at dynamical modelling speech time series. However, an additional finding is that the classical assumptions cannot be ruled out entirely, and plausible evidence is given to explain the success of the linear Gaussian theory as a weak approximation to the true, nonlinear/non-Gaussian dynamics. This supports the use of appropriate hybrid linear/nonlinear/non-Gaussian modelling. With a calibrated calculation of statistic and particular choice of experimental protocol, some of the known systematic problems of the method of surrogate data testing are circumvented to obtain results to support the conclusions to a high level of significance

Developing Organ Offer and Acceptance Measures: When ‘Good’ Organs Are Turned Down

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75521/1/j.1600-6143.2007.01784.x.pd

Analysis of U.S. Water Resources under Climate Change

The MIT Integrated Global System Model (IGSM) framework, extended to include a Water Resource System (WRS) component, is applied to an integrated assessment of effects of alternative climate policy scenarios on U.S. water systems. Climate results are downscaled to yield estimates of surface runoff at 99 river basins of the continental U.S., with an exploration of climate patterns that are relatively wet and dry over the region. These estimates are combined with estimated groundwater supplies. An 11-region economic model (USREP) sets conditions driving water requirements estimated for five use sectors, with detailed sub-models employed for analysis of irrigation and electric power. The water system of the interconnected basins is operated to minimize water stress. Results suggest that, with or without climate change, U.S. average annual water stress is expected to increase over the period 2041 to 2050, primarily because of an increase in water requirements, with the largest water stresses projected in the South West. Policy to lower atmospheric greenhouse gas concentrations has a beneficial effect, reducing water stress intensity and variability in the concerned basins.The Joint Program on the Science and Policy of Global Change is funded by the U.S. Department of Energy, Office of Science under grants DE-FG02-94ER61937, DE-FG02- 93ER61677, DEFG02-08ER64597, and DE-FG02-06ER64320; the U.S. Environmental Protection Agency under grants XA-83344601-0, XA-83240101, XA-83042801-0, PI-83412601- 0, RD-83096001, and RD-83427901-0; the U.S. National Science Foundation under grants SES- 0825915, EFRI-0835414, ATM-0120468, BCS-0410344, ATM-0329759, and DMS-0426845; the U.S. National Aeronautics and Space Administration under grants NNX07AI49G, NNX08AY59A, NNX06AC30A, NNX09AK26G, NNX08AL73G, NNX09AI26G, NNG04GJ80G, NNG04GP30G, and NNA06CN09A; the U.S. National Oceanic and Atmospheric Administration under grants DG1330-05-CN-1308, NA070AR4310050, and NA16GP2290; the U.S. Federal Aviation Administration under grant 06-C-NE-MIT; the Electric Power Research Institute under grant EPP32616/C15124; and a consortium of 40 industrial and foundation sponsors (for the complete list see http://globalchange.mit.edu/sponsors/current.html

Modeling Water Resource Systems under Climate Change: IGSM-WRS

Through the integration of a Water Resource System (WRS) component, the MIT Integrated Global System Model (IGSM) framework has been enhanced to study the effects of climate change on managed water-resource systems. Development of the WRS involves the downscaling of temperature and precipitation from the zonal representation of the IGSM to regional (latitude-longitude) scale, and the translation of the resulting surface hydrology to runoff at the scale of river basins, referred to as Assessment Sub-Regions (ASRs). The model of water supply is combined with analysis of water use in agricultural and non-agricultural sectors and with a model of water system management that allocates water among uses and over time and routes water among ASRs. Results of the IGSM-WRS framework include measures of water adequacy and ways it is influenced by climate change. Here we document the design of WRS and its linkage to other components of the IGSM, and present tests of consistency of model simulations with the historical record.The Joint Program on the Science and Policy of Global Change is funded by the U.S. Department of Energy, Office of Science under grants DE-FG02-94ER61937, DE-FG02-93ER61677, DEFG02- 08ER64597, and DE-FG02-06ER64320; the U.S. Environmental Protection Agency under grants XA-83344601-0, XA-83240101, XA-83042801-0, PI-83412601-0, RD-83096001, and RD- 83427901-0; the U.S. National Science Foundation under grants SES-0825915, EFRI-0835414, ATM-0120468, BCS-0410344, ATM-0329759, and DMS-0426845; the U.S. National Aeronautics and Space Administration under grants NNX07AI49G, NNX08AY59A, NNX06AC30A, NNX09AK26G, NNX08AL73G, NNX09AI26G, NNG04GJ80G, NNG04GP30G, and NNA06CN09A; the U.S. National Oceanic and Atmospheric Administration under grants DG1330-05-CN-1308, NA070AR4310050, and NA16GP2290; the U.S. Federal Aviation Administration under grant 06-C-NE-MIT; the Electric Power Research Institute under grant EPP32616/ C15124; and a consortium of 40 industrial and foundation sponsors (for the complete list see http://globalchange.mit.edu/sponsors/current.html)