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Robust denoising of electrophoresis and mass spectrometry signals with minimum description length principle.

The need for high-throughput assays in molecular biology places increasing requirements on the applied signal processing and modelling methods. In order to be able to extract useful information from the measurements, the removal of undesirable signal characteristics such as random noise is required. This can be done in a quite elegant and efficient way by the minimum description length (MDL) principle, which treats and separates 'noise' from the useful information as that part in the data that cannot be compressed. In its current form the MDL denoising method assumes the Gaussian noise model but does not require any ad hoc parameter settings. It provides a basis for high-speed automated processing systems without requiring continual user interventions to validate the results as in the conventional signal processing methods. Our analysis of the denoising problem in mass spectrometry, capillary electrophoresis genotyping, and sequencing signals suggests that the MDL denoising method produces robust and intuitively appealing results sometimes even in situations where competing approaches perform poorly.

Algorithms↗

[Idiopathic subarachnoid hemorrhage: is the perimesencephalic distribution that benign?].

INTRODUCTION: Idiopathic subarachnoid hemorrhage (iSAH) is generally recognized as benign especially if its distribution is perimesencephalic. In this study we assessed the complications following an iSAH and analyzed them in relation to the perimesencephalic or diffuse distribution of the hemorrhage. METHOD: Retrospective study of 1,148 consecutive patients evaluated between January 1990 and April 2001 for iSAH documented by cerebral CT-scan with normal cerebral angiographic work-up. RESULTS: Of the eighty-seven patients (7.6%) presenting with iSAH, 52 presented with a perimesencephalic distribution, and 35 with a diffuse distribution. No statistically significant difference was observed between the two distributions with regards to complications following the hemorrhage, such as hydrocephalus, neurological deficits due to vasospasm, systemic effects and mortality. Fisher grade III was associated with an increased risk of complications. CONCLUSION: Perimesencephalic iSAH is not exempt from complications. Morbidity and mortality in this group are comparable to those observed in diffuse iSAH. The Fisher grade is a predicting factor of complications for any given hemorrhage distribution.

Cause of Death↗

Scanning electron microscopy of human cerebral meningeal stomata.

The human dura mater and pia mater were studied by using a scanning electron microscope and a computer image processing system (C.I.P.). The human cerebral meningeal stomata are located between the mesothelial cells of the cerebral meninges. They are round or oval in shape with diameters of 0.33-2.98 microns. The cerebral meningeal stomata are stable structures, scattered or clustered together. Their density in the dura mater is greater than in the pia mater (P < 0.01), and they are regularly distributed. The statistical analysis showed that the stomata diameter and distribution density in the dura mater are 1.34 microns and 381.55/0.1 mm2; while in the pia mater they are 0.88 micron and 195.06/0.1 mm2 respectively. The cerebral meningeal stomata are probably part of the cerebral prelymphatic capillary system, which undertakes the cerebral lymph drainage because there are no lymphatic vessels in the brain although yet there is lymph drainage. Thus, we believe that the cerebral meningeal stomata are involved in maintaining the physiological function of the brain as part of the cerebrospinal fluid (CSF) which absorbs the cerebral interstitial fluid.

Dura Mater↗

Design of random copolymers with statistically controlled monomer sequence distributions via Monte Carlo simulations.

We use Monte Carlo simulations to model the formation of random copolymers with tunable monomer sequence distributions. Our scheme is based on the original idea proposed a few years ago by Khokhlov and Khalatur [Physica A 249, 253 (1998); Phys. Rev. Lett. 82, 3456 (1999)], who showed that the distribution of species B in A-B random copolymers can be regulated by (a) adjusting the coil size of a homopolymer A and (b) chemically modifying ("coloring") monomers that reside at (or close to) the periphery of the coil with species B. In contrast to Khokhlov and Khalatur's work, who modeled the polymer modification by performing the coloring instantaneously, we let the chemical coloring reaction progress over time using computer simulations. We show that similar to Khokhlov and Khalatur's work, the blockiness (i.e., number of consecutive monomers) of the B species along the A-B copolymer increases with increasing degree of collapse of the parent homopolymer A. A simple analysis of the A-B monomer sequences in the copolymers reveals that monomer sequence distributions in homopolymers "colored" under collapsed conformations possess certain degrees of self-similarity, while there is no correlation found among the monomer sequence distributions formed by coloring homopolymers with expanded conformations.

Journal Article↗

Fertility determinants in the oil region of Mexico.

This study analyzes fertility determinants in the oil region of Mexico, consisting of the states of Veracruz, Tabasco, and Campeche. Data are from the 1980 Mexican census and the unit of analysis is the municipio. The regression models, in which the dependent variables of children ever born and child-woman ratio are examined, reveal religious variables to be most significant, with greater fertility for non-Catholics and persons with no religion than for Catholics. Also of great importance are economic variables. Literacy and urbanization, both "classical" Mexican fertility variables, reduce fertility. There are major differences among three urban/rural and three indigenous language subsamples. Results are discussed vis-a-vis demographic theories and prior research.

Adolescent↗

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Demography↗

Geographic distribution of undocumented immigrants: estimates of undocumented aliens counted in the 1980 census by state.

"This article presents estimates of the number of undocumented aliens counted in the 1980 [U.S.] census for each state and the District of Columbia. The estimates, which indicate that 2.06 million undocumented aliens were counted in the 1980 census, are not based on individual records, but are aggregate estimates derived by a residual technique. The census count of aliens (modified somewhat to account for deficiencies in the data) is compared with estimates of the legally resident alien population based on data collected by the Immigration and Naturalization Service in January 1980." Estimates are provided "for each of the states for selected countries of birth and for age, sex, and period of entry categories.... The origins of the undocumented alien population [are described], as well as some of their demographic characteristics. Some of the implications of the numbers and distribution of undocumented aliens are also discussed." This paper was originally presented at the 1984 Annual Meeting of the Population Association of America (see Population Index, Vol. 50, No. 3, Fall 1984, p. 435).

Age Distribution↗