"Building" exact confidence nets

Confidence nets, that is, collections of confidence intervals that fill out the parameter space and whose exact parameter coverage can be computed, are familiar in nonparametric statistics. Here, the distributional assumptions are based on invariance under the action of a finite reflection group. Exact confidence nets are exhibited for a single parameter, based on the root system of the group. The main result is a formula for the generating function of the coverage interval probabilities. The proof makes use of the theory of "buildings" and the Chevalley factorization theorem for the length distribution on Cayley graphs of finite reflection groups.Comment: 20 pages. To appear in Bernoull

Estimating the accuracy of geographical imputation

<p>Abstract</p> <p>Background</p> <p>To reduce the number of non-geocoded cases researchers and organizations sometimes include cases geocoded to postal code centroids along with cases geocoded with the greater precision of a full street address. Some analysts then use the postal code to assign information to the cases from finer-level geographies such as a census tract. Assignment is commonly completed using either a postal centroid or by a geographical imputation method which assigns a location by using both the demographic characteristics of the case and the population characteristics of the postal delivery area. To date no systematic evaluation of geographical imputation methods ("geo-imputation") has been completed. The objective of this study was to determine the accuracy of census tract assignment using geo-imputation.</p> <p>Methods</p> <p>Using a large dataset of breast, prostate and colorectal cancer cases reported to the New Jersey Cancer Registry, we determined how often cases were assigned to the correct census tract using alternate strategies of demographic based geo-imputation, and using assignments obtained from postal code centroids. Assignment accuracy was measured by comparing the tract assigned with the tract originally identified from the full street address.</p> <p>Results</p> <p>Assigning cases to census tracts using the race/ethnicity population distribution within a postal code resulted in more correctly assigned cases than when using postal code centroids. The addition of age characteristics increased the match rates even further. Match rates were highly dependent on both the geographic distribution of race/ethnicity groups and population density.</p> <p>Conclusion</p> <p>Geo-imputation appears to offer some advantages and no serious drawbacks as compared with the alternative of assigning cases to census tracts based on postal code centroids. For a specific analysis, researchers will still need to consider the potential impact of geocoding quality on their results and evaluate the possibility that it might introduce geographical bias.</p

Geographic disparities in colorectal cancer survival

© 2009 Henry et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Optical diagnostics and therapeutics in peripheral nerve surgery.

Despite advances in clinical practice Sunderland\u27s grades of nerve injury as described in 1951 remain a clinical measurement often aided by non specific diagnostic tools such as neurophysiological testing or indeed verified experimentally by destructive histological techniques. Furthermore regarding grade 5 injuries or nerve transection, microsurgical repair with sutures has remained the gold standard clinically despite a relatively poor outcome when the regenerative capability of the neural microenvironment is considered. The objectives of this thesis are to apply novel optical technologies across the spectrum of nerve injuries as described by Sunderland. This includes evaluation of two optical diagnostic microscopes as well as a light activated neurorrhaphy addressing a grade 5 injury. We hypothesize that Optical microscopy may have a role in analyzing injury to, and the recovery of, the peripheral nerve in vivo. Utilising Coherent Anti-stokes Raman Scattering (CARS) Microscopy to categorize peripheral nerve damage in vivo, and to monitor the recovery process of a damaged nerve and a Multifunctional Optical Coherence Tomography (OCT) system to assess quantitative and qualitative changes in optical density and polarisation of nerve tissue following injury. Regarding grade 5 injury we hypothesis that isolation of the nerve repair site using photochemical tissue bonding (PTB) in combination with human amniotic membrane can improve both functional and histological recovery. Optical Diagnostics: A demyelinating crush injury was reproduced in the sciatic nerves of Sprague Dawley rats. Animals were randomised into groups and optical microscopy was undertaken at day one and weekly up to four weeks following completed following imaging. The uninjured nerve was used as a control. All animals demonstrated loss of sciatic nerve function following injury. Recovery was documented with functional data approaching normal at three and four weeks. Demyelination was confirmed using CARS Microscopy in nerves up to two weeks post injury, remyelination was observed in the three week group and beyond. Imaging of normal nerve revealed structured myelin bundles. These results were consistent with histology. OCT imaging revealed a quantifiable change in birefringence of the nerve (as measured by phase retardation graphs) following a simple crush injury. Histological markers of axonal myelination such as myelin thickness and g-ratio (axon diameter / fiber diameter) were then calculated and directly compared to the slope of the graph obtained from imaging (Birefkingence). Scatter plot analysis of the complete data set showed a statistically significant relationship with both myelin thickness and g-ratio when compared to imaging results. Optical Therapeutics: Photochemical tissue bonding (PTB) is a sutureless tissue repair process that seals the repair site allowing prompt restoration of the normal endoneural environment and healing. In PTB, a photoactive dye is applied to tissue surfaces that are then placed in contact and irradiated with green light. This technique utilises visible light at a power that does not thermally damage the tissue. The light activates the dye leading to immediate formation of covalent crosslinks between proteins on both surfaces, thereby forming a water tight seal. New Zealand White Rabbits (n = 24) underwent transection of the right common peroneal nerve. Standard neurorrhaphy (SN) was performed using 10/0 nylon sutures. The repair site was then wrapped in a cuff of human amniotic membrane(HAM), which was either secured with sutures (SN \u26 HAM) or sealed using PTB (SN \u26 HAMIPTB). Standard neurorrhaphy alone was assessed as a control group. Functional recovery was recorded at 30 day intervals post-operatively by electrophysiological assessment. At 120 days animals were sacrificed and nerves harvested for histomorphometry. Nerves treated with amnion wraps, sealed with PTB demonstrated a statistically significant improvement across both functional and histological parameters. Functional recovery, as measured by repeated electrophysiological studies over time, revealed a 26.2% improvement over standard neurorrhaphy alone (p\u3c0.05). Nervestreated with PTB sealed amnion wraps had significantly (p \u3c0.001) greater axon fibre diameters as well as myelin thickness and G-ratio distal to the repair site compared to standard neurorrhaphy alone. In conclusion, both CARS Microscopy and OCT have the ability to image the peripheral nerve revealing structural (CARS) as well as quantitative and qualitative changes (OCT) in composition which may be used to grade injury and regeneration over time and isolation of the peripheral nerve repair site using a photochemically sealed amnion wrap improves electrophysiological and histological recovery when compared to that of standard suture neurorrhaphy

Planetary systems around close binary stars: the case of the very dusty, Sun-like, spectroscopic binary BD+20 307

Field star BD+20 307 is the dustiest known main sequence star, based on the fraction of its bolometric luminosity, 4%, that is emitted at infrared wavelengths. The particles that carry this large IR luminosity are unusually warm, comparable to the temperature of the zodiacal dust in the solar system, and their existence is likely to be a consequence of a fairly recent collision of large objects such as planets or planetary embryos. Thus, the age of BD+20 307 is potentially of interest in constraining the era of terrestrial planet formation. The present project was initiated with an attempt to derive this age using the Chandra X-ray Observatory to measure the X-ray flux of BD+20 307 in conjunction with extensive photometric and spectroscopic monitoring observations from Fairborn Observatory. However, the recent realization that BD+20 307 is a short period, double-line, spectroscopic binary whose components have very different lithium abundances, vitiates standard methods of age determination. We find the system to be metal-poor; this, combined with its measured lithium abundances, indicates that BD+20 307 may be several to many Gyr old. BD+20 307 affords astronomy a rare peek into a mature planetary system in orbit around a close binary star (because such systems are not amenable to study by the precision radial velocity technique).Comment: accepted for ApJ, December 10, 200

Re-identification of a lamnid shark embryo

nant female lamnid shark was caught that the morphometric arguments in the Strait of Messina, Mediterra- used by Sanzo (1912) did not rule out nean Sea. She was reported to contain the shortfin mako (Isurus oxyrinchus 25–30 embryos, one of which was Rafinesque, 1810) but that the high saved and taken to the local Marine fecundity of 25–30 was more consis-Institute, where it was subsequently tent with C. carcharias than with I. examined by Sanzo (1912). The male oxyrinchus or a Lamna species. A lack embryo measured 36.1 cm total length of information on lamnid reproduction (TL), weighed 800 g, and had a greatly and the misidentification of a likely distended abdomen, as is typical of Galeorhinus galeus (Stevens2) with a embryos of oophagous lamnoid sharks litter of 30 as Lamna by Neill (1811), (Gilmore, 1993). The mother and the may have led Sanzo (1912) to consider remaining embryos were not saved. the porbeagle Lamna nasus (Bon-Because Sanzo was not able to exam- naterre, 1788) instead of the shortfin ine the adult female from which the mako as the most likely alternativ

The Dusty, Solar Type Spectroscopic Binary BD +20 307

The dustiest known main‐sequence star, BD +20 307, is actually a double‐lined binary with a period of 3.4202 days and a circular orbit. The system is also metal poor with [Fe/H] = −0.4. The components are late‐F and early‐G dwarfs and have a mass ratio of 1.07. The photometric period of about 3.5 days indicates that the components are synchronously rotating. The metal poor, binary nature invalidates the idea that the object is a very young single star with a warm planet‐making dust disk. Instead, the metal poor nature of the system and the lithium abundances of the components argue that the system is likely several billion years old, and so the dust disk results from the recent collision of two planetary mass rocky objects. Thus, BD +20 307 may well be the first known system with planets orbiting a close binary star

Arctic system on trajectory to new state

The Arctic system is moving toward a new state that falls outside the envelope of glacial-interglacial fluctuations that prevailed during recent Earth history. This future Arctic is likely to have dramatically less permanent ice than exists at present. At the present rate of change, a summer ice-free Arctic Ocean within a century is a real possibility, a state not witnessed for at least a million years. The change appears to be driven largely by feedback-enhanced global climate warming, and there seem to be few, if any processes or feedbacks within the Arctic system that are capable of altering the trajectory toward this “super interglacial” state

Ernst Freund as Precursor of the Rational Study of Corporate Law

Gindis, David, Ernst Freund as Precursor of the Rational Study of Corporate Law (October 27, 2017). Journal of Institutional Economics, Forthcoming. Available at SSRN: https://ssrn.com/abstract=2905547, doi: https://dx.doi.org/10.2139/ssrn.2905547The rise of large business corporations in the late 19th century compelled many American observers to admit that the nature of the corporation had yet to be understood. Published in this context, Ernst Freund's little-known The Legal Nature of Corporations (1897) was an original attempt to come to terms with a new legal and economic reality. But it can also be described, to paraphrase Oliver Wendell Holmes, as the earliest example of the rational study of corporate law. The paper shows that Freund had the intuitions of an institutional economist, and engaged in what today would be called comparative institutional analysis. Remarkably, his argument that the corporate form secures property against insider defection and against outsiders anticipated recent work on entity shielding and capital lock-in, and can be read as an early contribution to what today would be called the theory of the firm.Peer reviewe

Extracting structural features of rat sciatic nerve using polarization-sensitive spectral domain optical coherence tomography

We present spectral domain polarization-sensitive optical coherence tomography (SD PS-OCT) imaging of peripheral nerves. Structural and polarization-sensitive OCT imaging of uninjured rat sciatic nerves was evaluated both qualitatively and quantitatively. OCT and its functional extension, PS-OCT, were used to image sciatic nerve structure with clear delineation of the nerve boundaries to muscle and adipose tissues. A long-known optical effect, bands of Fontana, was also observed. Postprocessing analysis of these images provided significant quantitative information, such as epineurium thickness, estimates of extinction coefficient and birefringence of nerve and muscle tissue, frequency of bands of Fontana at different stretch levels of nerve, and change in average birefringence of nerve under stretched condition. We demonstrate that PS-OCT combined with regular-intensity OCT (compared with OCT alone) allows for a clearer determination of the inner and outer boundaries of the epineurium and distinction of nerve and muscle based on their birefringence pattern. PS-OCT measurements on normal nerves show that the technique is promising for studies on peripheral nerve injury. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE)