Dynamic time warping is a procedure whereby portions of a temporal sequence of values are stretched or shrunk to make it similar to another sequence. This procedure can be used to align the brain-stem auditory evoked potentials recorded from different subjects prior to averaging. The resultant warp-average more closely resembles the wave form of a typical subject than the conventional average. Dynamic time warping can also be used to compare one brain-stem auditory evoked potential to another. This comparison can show the differences that result from changes in a stimulus parameter such as intensity or repetition rate. When a patient's wave form is compared to a normal template, warping can identify the peaks in the patient's wave form that correspond most closely to the peaks in the normal template. Compared to an experienced human interpreter, warping is very accurate in identifying the waves of normal brain-stem auditory evoked potentials (error rate between 0 and 4%) and reasonably accurate in identifying the peaks in abnormal wave forms (error rate between 3 and 18%).

Adult↗

PubMedDate not supplied

Investigation of risk factors for porcine Taenia solium cysticercosis: a multiple regression analysis of a cross-sectional study in the Yucatan Peninsula, Mexico.

A cross-sectional survey for seropositivity to cysticercosis of pigs in the Yucatan Peninsula, Mexico, was carried out in 1996 together with a standardized questionnaire on predetermined individual pig and household risk factors for porcine infection. Serum samples from 697 pigs were analysed by immunoblot for antibodies to Taenia solium cysticercosis and questionnaires from 227 households in 18 villages were collected. All the data were analysed using multivariate analytical techniques taking household clustering into account. The overall porcine seroprevalence in the area was found to be 29%. The most important risk factors for seropositivity in pigs were presence versus absence of a toilet (adjusted odds ratio [adj. OR] 2.37, P = 0.005), crowded households (adj. OR 1.75, P = 0.034) and both corralling (adj. OR 2.14, P = 0.017) and letting pigs loose (adj. OR 2.32, P = 0.035) versus tying them up. There was evidence of clustering at household level and that possible risk factors at municipal or village level may also interact with higher risk management practices such as allowing pigs to run loose.

Animal Husbandry↗

PubMedDate not supplied

A simple stochastic model of spatially complex neurons.

A method for studying the coding properties of a multicompartmental integrate-and-fire neuron of arbitrary geometry is presented. Depolarization at each compartment evolves like a leaky integrator with an after-firing reset imposed only at the trigger zone. The frequency of firing at the steady-state regime is related to the properties of the multidimensional input. The decreasing variability of subthreshold depolarization from the dendritic tree to the trigger zone is shown for an input that is corrupted by a white noise. The role of a Poissonian noise is also investigated. The proposed method gives an estimate of the mean interspike interval that can be used to study the input output transfer function of the system. Both types of the stochastic inputs result in broadening the transfer function with respect to the deterministic case.

Models, Neurological↗

PubMedDate not supplied

Noisy spiking neurons and networks: useful approximations for firing probabilities and global behavior.

Electrophysiological properties of spiking neurons receiving complex stimuli perturbed by noise are investigated. A semi-analytical estimate of firing probabilities and subthreshold behavior of the stochastic system can be made in terms of the solution of a purely deterministic system. The method comes from an approximation for the distribution function and moments of the underlying non linear multidimensional diffusion process. This so called moment method works for general conductance-based systems and an application is presented for the Hodgkin-Huxley neuronal model. Statistical properties obtained from the moment method are compared with direct numerical integration of the stochastic system. The firing probability due to external noise is derived as a closed formula. Results are given for different forms of the deterministic component of the stimulus. A generalization to neural networks of conductance-based systems with internal currents perturbed by noise can be obtained using the same approach. In the case of fully connected networks, a mean field population equation is derived which may be compared to Kuramoto's master equation for weakly coupled neural oscillators.

Action Potentials↗

PubMedDate not supplied

[Statistical study of the electroencephalographic correlations between clinical and anatomical data. Application in 100 cases of cerebral abscess].

Explore the source record for details and available documents.

Brain Abscess↗

PubMedDate not supplied

Full window stereo.

Visualisation is the bioinformaticist's most important tool for the study of macromolecules, and being able to see molecules in stereo is a crucial aspect. Stereo vision is based on the principle that each eye is presented with the best possible image of what it would have seen if the object was really there in 3D. The simplest approach to stereo vision is to display the right eye picture on the right half of the screen and the left eye picture on the left half while using a mirror system to ensure that each eye sees what it is supposed to see. More expensive workstations use hardware to alternately display the left and right eye pictures while synchronously blocking the transparency in the right or left lens of the special glasses worn by the user. We present here some simple software that uses inexpensive hardware, originally designed for the computer game industry, to make full screen stereo available on Linux-based PCs. The quality of the stereo vision is similar to the top-of-the-line graphics workstations that are capable of quad-buffering. This stereo option has been incorporated in the XII based version of WHAT IF (Vriend, G. J. Mol. Graphics 1990, 8, 52-56), but the stereo source code is freely available and can easily be incorporated in other visualization packages.

Humans↗

PubMedDate not supplied

The influence of the menstrual cycle in postdural puncture headache.

BACKGROUND AND OBJECTIVES: We performed a preliminary study to analyze the influence of the menstrual cycle on the incidence of postdural puncture headache (PDPH). METHODS: One hundred sixty female patients with regular menstrual cycles who received spinal anesthesia were observed. Based on the day within the menstrual cycle that they received the puncture, the patients were classified into period A (perimenstrual) or period B (postmenstrual). The possible relationship among headaches, lifestyle habits, and anesthetic technique, and the presence of PDPH were analyzed, as were the levels of female sex hormones with PDPH in comparison with a control group. RESULTS: Seven cases of PDPH (4.3%) were observed--one within the perimenstrual group and six in the postmenstrual group. No significant differences were observed between the two periods or were there any differences in relating PDPH to the other variables analyzed. CONCLUSIONS: According to our results, the menstrual cycle and hormonal levels may not have any influence on the appearance of PDPH in female patients, although a larger series is required to validate these results.

Adult↗

PubMedDate not supplied

De Madres a Madres: women building community coalitions for health.

How one group of Hispanic women in Houston, Texas, built community coalitions for primary health care is chronicled from the perspectives of the women. We describe how they formed partnerships with community businesses, health and social service agencies, schools, and churches to develop an outreach network that enables pregnant women to obtain early prenatal care. These women's steps in coalition building are related to feminist theory, with an emphasis on group decision making, shared power for the empowerment of all, and the creation of an environment in which individual worth and dignity are enhanced and risk taking is encouraged and supported.

Community Participation↗

PubMedDate not supplied

The power of the collective: battered migrant farmworker women creating safe spaces.

In this article I describe the use of a participatory action research (PAR) methodology to address the problem of domestic violence among migrant farmworker (MFW) women in California. The article was generated from a variety of data sources used by the investigator over a 4-year period. These include the investigator's observations, field notes, informal conversations, written stories from the women, and interviews. The "power of the collective" is discussed as the development of a power base for battered MFW women to support and take care of one another. The concepts of liberation, enlightenment, and "conscientizacion" are used to describe the evolution of the collective.

Adult↗

PubMedDate not supplied

A death from fentanyl overdose.

A case of death from self-injection of fentanyl and a method for its detection in autopsy specimens are reported. Fentanyl was measured by extraction of biological samples with ethyl acetate, partitioning into 0.1N HCl, then reextracting into ethyl acetate after alkalinization of the acid phase. After reducing to a residue, the fentanyl was measured by selective ion monitoring gas chromatography/mass spectrometry. Concentrations of 4.8, 6.3, and 4.7 micrograms/L were found in blood, urine, and bile, respectively.

Adult↗

PubMedDate not supplied

Dose levels due to neutrons in the vicinity of high-energy medical accelerators.

High-energy photons are generated for use in radiation therapy by the deceleration of electrons in metal targets. Fast neutrons are also generated as a result of (gamma, n) and (e, e'n) interactions in the target, beam compensator filter, and collimator material. In this work the absorbed dose due to neutrons was measured at the center of a 10 X 10-cm photon beam and 5 cm outside of the beam edge for a number of treatment units (Varian Clinac-18, Allis-Chalmers 25-MeV betatron, and Brown Boveri 45-MeV betatron). Dose levels due to slow and fast neutrons were also established outside of the treatment rooms and a Bonner sphere neutron spectrometer system was employed to determine the neutron energy spectrum due to stray neutron radiation at each accelerator. For the linac it was found that the neutron dose at the beam center was 0.0039% of the photon dose and values of 0.04% and 0.053% were observed for the Allis-Chalmers betatron and the Brown Boveri betatron. Dose-equivalent rates in the range 0.3-22.5 mrem were measured for points outside the treatment rooms when the accelerators were operated at a photon dose rate of 100 rad/min at the treatment position.

Environmental Exposure↗

PubMedDate not supplied

Nuclear grade and DNA ploidy in stage IV breast cancer with only visceral metastases at initial diagnosis.

AIMS AND BACKGROUND: The presence of early metastases to distant sites in breast cancer patients is an infrequent event whose mechanisms are still not clear. The aim of this study was to evaluate the biologic and clinical role of DNA ploidy and cell nuclear grade of primary tumors in the metastatic process of a series of stage IV previously untreated breast cancer patients with only visceral metastases. METHODS: DNA flow cytometry analysis on paraffin-embedded material and cell nuclear grading of primary tumors was performed on a series of 50 breast cancer patients with only visceral metastases at the time of initial diagnosis. RESULTS: Aneuploidy was found in 28/46 (61%) of evaluable cases and was independent of site of involvement, clinical response, time of progression and overall survival of patients. Of the 46 cases evaluable for nuclear grade, 5 (11%), 16 (35%) and 25 (54%) were classified as G1 (well-differentiated) G2 and G3, respectively. Nuclear grade also was unrelated to response to therapy and overall survival, whereas time to progression was significantly longer in G1-2 than G3 tumors with the logrank test (P < 0.03) and multivariate analysis. CONCLUSIONS: Our results seem to stress the difficulty to individualize different prognostic subsets from a series of breast cancer patients with only visceral metastases at initial diagnosis according to DNA flow cytometry and nuclear grade.

Adult↗