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J Sweeney

Publications and source records attributed to J Sweeney.

At least 19 recordsLinked to original sources
PubMed2005

Estimation of the cortical functional connectivity with the multimodal integration of high-resolution EEG and fMRI data by directed transfer function.

Nowadays, several types of brain imaging device are available to provide images of the functional activity of the cerebral cortex based on hemodynamic, metabolic, or electromagnetic measurements. However, static images of brain regions activated during particular tasks do not convey the information of how these regions communicate with each other. In this study, advanced methods for the estimation of cortical connectivity from combined high-resolution electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) data are presented. These methods include a subject's multicompartment head model (scalp, skull, dura mater, cortex) constructed from individual magnetic resonance images, multidipole source model, and regularized linear inverse source estimates of cortical current density. Determination of the priors in the resolution of the linear inverse problem was performed with the use of information from the hemodynamic responses of the cortical areas as revealed by block-designed (strength of activated voxels) fMRI. We estimate functional cortical connectivity by computing the directed transfer function (DTF) on the estimated cortical current density waveforms in regions of interest (ROIs) on the modeled cortical mantle. The proposed method was able to unveil the direction of the information flow between the cortical regions of interest, as it is directional in nature. Furthermore, this method allows to detect changes in the time course of information flow between cortical regions in different frequency bands. The reliability of these techniques was further demonstrated by elaboration of high-resolution EEG and fMRI signals collected during visually triggered finger movements in four healthy subjects. Connectivity patterns estimated for this task reveal an involvement of right parietal and bilateral premotor and prefrontal cortical areas. This cortical region involvement resembles that revealed in previous studies where visually triggered finger movements were analyzed with the use of separate EEG or fMRI measurements.

Adult↗
PubMed2005

Estrous cycle characterisation and artificial insemination using frozen-thawed spermatozoa in the bottlenose dolphin (Tursiops truncatus).

The reproductive endocrinology of the bottlenose dolphin, Tursiops truncatus, was characterized to facilitate the development of artificial insemination using cryopreserved spermatozoa. Specific objectives were: (i) to determine the excretory dynamics of urinary luteinizing hormone (LH) and ovarian steroid metabolites during the estrous cycle; (ii) to evaluate the effect of an exogenously administered synthetic progesterone analog (altrenogest) on reproductive hormone excretion; (iii) to correlate follicular growth and ovulation (as determined by transabdominal ultrasound) to urinary LH and ovarian steroid metabolites; (iv) examine the in vivo fertilisation capacity of cryopreserved semen, and (v) to develop an intrauterine insemination technique. Based on urinary endocrine monitoring of natural estrous cycles (2 consecutive cycles) and nine post altrenogest cycles in ten females, estrous cycles were found to be 36 days long and comprised of an 8 day and 19 day follicular and luteal phase, respectively. Peak estrogen conjugates (EC; 5.4+/-3.8 ng/mg creatinine (Cr)) occurred 8 h prior to the LH surge (70.9+/-115.7 ng/mg Cr). The time of ovulation, as determined by ultrasonography, occurred 32.1+/-8.9 h and 24.3+/-7.0 h after the onset of the LH surge and LH peak, respectively. Mean preovulatory follicular diameter and circumference were 2.1+/-0.5 cm and 6.5+/-1.5 cm, respectively. Of the 27 estrous synchronisation attempts, 13 resulted in an ovulatory cycle, with ovulation occurring 21 days post-altrenogest treatment. Intrauterine (4 of 5) and intracornual (1 of 3) inseminations conducted across eight estrous cycles resulted in five pregnancies (63%), one pregnancy resulted from the use of liquid stored semen, whereas four were achieved using cryopreserved semen. These data provide new information on female bottlenose dolphin reproductive physiology, and demonstrate that the combination of endocrine monitoring and serial ultrasonography contributed to successful AI using liquid-stored and cryopreserved semen.

Animals↗
PubMed2002

Theoretical and finite-element investigation of the mechanical response of spinodal structures.

In recent years there have been major advances in our understanding of the mechanisms of phase separation in polymer and copolymer blends, to the extent that good control of phase-separated morphology is a real possibility. Many groups are studying the computational simulation of polymer phase separation. In the light of this, we are exploring methods which will give insight into the mechanical response of multiphase polymers. We present preliminary results from a process which allows the production of a two-dimensional finite-element mesh from the contouring of simulated composition data. We examine the stretching of two-phase structures obtained from a simulation of linear Cahn-Hilliard spinodal phase separation. In the simulations, we assume one phase to be hard, and the other soft, such that the shear modulus ratio G is large (>or= 10(3)). We indicate the effect of varying composition on the material modulus and on the distribution of strains through the stretched material. We also examine in some detail the symmetric structures obtained at 50% composition, in which both phases are at a percolation threshold. Inspired by simulation results for the deformation of these structures, we construct a "scaling" theory, which reproduces the main features of the deformation. Of particular interest is the emergence of a lengthscale, below which the deformation is non-affine. This length is proportional to G(1/4), and hence is still quite small for all reasonable values of this ratio. The same theory predicts that the effective composite modulus scales also as G(1/4), , which is supported by the simulations.

Journal Article↗
PubMed2000

Three words three shapes: A clinical test of memory.

Three Words - Three Shapes was designed as an easy "bedside" test for elderly patients that assesses verbal and nonverbal memory within the same modality. In the present study, it was administered to patients with probable Alzheimer's disease (PRAD), a control group of non-demented older subjects (NC) and a group of patients with Korsakoff's amnesia (KA). Incidental recall and several other measures of learning, retention and recognition differentiated control from PRAD and KA subjects. PRAD and KA subjects' performance was similar, but there were some material-specific interactions. This test is relatively easy and some of the derived measures could prove useful in staging amnesia progression beyond the earliest stages of PRAD when more difficult tests yield floor effects.

Aged↗
PubMed2000

Interpretations and variations of ISO 9000 in acute health care. International Organization for Standardization.

OBJECTIVE: This paper aims to address two questions related to the implementation of the ISO 9000 Quality Management System standard in the acute health care sector: which countries have developed specific nationwide guidelines/interpretations? and what variances exist between the different interpretations of the ISO 9002 standard? DESIGN: The study was carried out via an assessment of the available guideline documents for the use of ISO 9000 in the acute health care sector. The interpretation of each document was examined for common elements and deviations from the commonly agreed terms. SETTING: Worldwide in the acute health care sector (excluding that of laboratories). STUDY PARTICIPANTS: Eighty-two international ISO members and/or quality health care organizations. RESULTS: The results showed variation in the interpretations of the ISO 9000 standard. In total, 16 of the clauses/subclauses note distinct variations, between one or more of the documents, which could alter the perception of the system. CONCLUSION: From examination of the six identified guideline documents, the claim that ISO 9000 introduces quality systems which are comparable from one country to another is unfounded in the acute health care sector.

Accreditation↗
PubMed1999

User views of a regional secure unit--findings from a patient satisfaction survey.

This paper includes key findings of a patient satisfaction survey, conducted within an English Medium Secure Unit, offering care and treatment for 45 male and female mentally disordered offenders. It aims to identify patients' perceptions of the quality of their care and other aspects of their lives within the secure unit. Following permission from the local Ethics Committee, two interviewers collected data within a two week period, using a semi-structured interview schedule. All but three of the respondents agreed to be interviewed. Talking to nurses was perceived as highly satisfying. However, provision for specific cultural and women's needs, facilities for visitors, opportunities to practise religious beliefs and access to care plans were highlighted as unsatisfactory. The study concludes with recommendations for improvement, some of which have already been considered and implemented.

Commitment of Persons with Psychiatric Disorders↗
PubMed1998

Quality assurance and standards for red cells and platelets.

Blood donations vary in composition because of considerable variation in donor cell counts and volume collected. In order to minimize the variation in end products produced, and reduce the likelihood of low quality products, a program called Quality Assurance (QA) is required. Agreement on minimal standards is useful, and a program of quality control (QC) is an important component of QA. However, while QC to ensure compliance with standards is desirable, the objective of manufacturing products of consistently high quality can only be achieved when attention is focused on total process control, self-auditing and the energetic management of errors.

Blood Banks↗
PubMed1998

Psychiatric comorbidity in methadone maintained patients.

Diagnosing comorbid psychiatric disorders in methadone maintained patients may help to identify subgroups with different outcomes and needs for treatment. In this study, 75 methadone maintenance clinic patients in treatment longer than 30 days were assessed with the Addiction Severity Index, Global Assessment Scale and Mini-Mental Status Exam, and were interviewed for DSM-III-R psychiatric diagnosis using the computerized Diagnostic Interview Schedule. Psychiatric diagnoses were prevalent in the sample with depression, phobic disorders, antisocial personality and generalized anxiety the most common. Both number of DSM-III-R diagnoses and severity of psychopathology were correlated with outcome measures such as concurrent drug abuse, family-social problems and employment status.

Adolescent↗
PubMed1997

Comparison of results of various methods used to determine the extent of modification of methoxy polyethylene glycol 5000-modified bovine cupri-zinc superoxide dismutase.

The protein bovine cupri-zinc superoxide dismutase (SOD) was modified by the reaction of lysine residues with an active ester of methoxy polyethylene glycol 5000 (PEG). The extent of modification was determined by capillary zone electrophoresis, matrix-assisted laser desorption/ionization mass spectrometry, Fourier-transform infrared spectroscopy, and Raman spectroscopy and after removing PEG by alkaline hydrolysis of the linkages to SOD followed by quantification of the released PEG using gel-permeation chromatography. There was generally good agreement among the results obtained by these techniques on a typical sample of the PEG-modified protein. The results, extent of protein modification, determined by the preceding methods were compared to that found from the classical trinitrobenzene sulfonic acid (TNBS) procedure. In addition to providing alternatives to the TNBS procedure, results from the described methodologies strongly suggest that the extent of modification determined from the TNBS procedure is overestimated.

Animals↗