Showing papers by "University of Lisbon published in 1997"

Primary progressive multiple sclerosis.

Abstract: Patients with multiple sclerosis who develop progressive disability from onset without relapses or remissions pose difficulties in diagnosis, monitoring of disease activity and treatment. There is a need to define the diagnostic criteria for this group more precisely and, in particular, to describe a comprehensive battery of investigations to exclude other conditions. The mechanisms underlying the development of disability and the role of MRI in monitoring disease activity in this clinical subgroup require elucidation, particularly in view of the lack of change on conventional imaging in the presence of continuing clinical deterioration. The prognosis is poor and there are currently no treatment trials for this form of the disease.

Search for neutral heavy leptons produced in Z decays

Abstract: Weak isosinglet Neutral Heavy Leptons (m) have been searched for using data collected by the DELPHI detector corresponding to 3:3 106 hadronic Z0 decays at LEP1. Four separate searches have been performed, for short-lived m production giving monojet or acollinear jet topologies, and for long-lived m giving detectable secondary vertices or calorimeter clusters. No indication of the existence of these particles has been found, leading to an upper limit for the branching ratio BR(Z0 ! m) of about 1:310−6 at 95% confidence level for m masses between 3.5 and 50 GeV/c2. Outside this range the limit weakens rapidly with the m mass. The results are also interpreted in terms of limits for the single production of excited neutrinos.

Lignans and isoflavonoids in plasma and prostatic fluid in men: Samples from Portugal, Hong Kong, and the United Kingdom

Abstract: BACKGROUND Chinese men have lower incidences of prostate cancer compared to men from Europe and North America. Asians consume large quantities of soya, a rich source of isoflavanoids phyto-oestrogens and have high plasma and urinary levels of these compounds. The mammalian lignans, enterolactone and enterodiol, are another group of weak plant oestrogens and are derived from seeds, cereals and grains. Vegetarians have high plasma and urinary concentrations of lignans. METHODS The concentrations lignans and isoflavonic phyto-oestrogens were determined by gas chromatography-mass spectrometry (GC-MS) in plasma and prostatic fluid from Portuguese, Chinese and British men consuming their traditional diets. RESULTS In prostatic fluid the mean concentrations of enterolactone wer 31, 162 and 20.3ng/ml for Hong Kong, Portugal and Britain respectively. Very high levels of enterolactone (〉600ng/ml) were observed in the prostatic fluid of some of the men fromPortugal. High concentrations of equol (3270 ng/ml) and daidzein (532 ng/ml) were found in a sample of prostatic fluid from Hong Kong. Higher mean levels of daidzein were observed in prostatic fluid from Hong Kong at 70ng/ml, compared to 4.6 and 11.3ng/ml in samples from Portugal and Britain respectively. Mean levels of daidzein were higher in the plasma samples from Hong Kong (31.3ng/ml) compared to those from Portugal (1.3ng/ml) and Britain (8.2ng/ml). In general, the mean plasma concentrations of enterolactone from the three centres were similar, at 6.2, 3.9 and 3.9ng/ml in samples from Hong Kong, Portugal and Britain respectively. CONCLUSIONS Higher concentrations of the isoflavanoid phyto-oestrogens, daidzein and equol, were found in the plasma and prostatic fluid of men from Hong Kong, compared to those from Britain and Portugal. However, the levels of the lignan, enterolactone, were very much higher in prostatic fluid of Portuguese men. Isoflavanoids and lignans have many interesting properties and may, in part, be responsible for lower incidences of prostate cancer in men from Asia and also some Mediterranean countries. The isoflavanoids from soya, which are present in high concentrations in the prostatic fluid of Asian men, may be protective against prostate disease. Prostate 32:122–128, 1997. ©1997 Wiley-Liss, Inc.

Effects of a self-etching primer on enamel shear bond strengths and SEM morphology.

Abstract: PURPOSE: To study a dental adhesive system containing a self-etching primer, by evaluating the enamel shear bond strengths and comparing the SEM interfacial morphology. MATERIALS AND METHODS: 100 flat enamel bonding sites were prepared to 600-grit on proximal surfaces of caries-free human molars. The bonding surfaces were treated with Clearfil Liner Bond 2 as recommended by the manufacturer, or combined with various acidic etchants. A composite rod (Clearfil Photo Anterior) was applied to the bonding area in two increments in a Teflon mold and polymerized for 100 s. After 24 h of water storage, the specimens were thermocycled and the shear bond strengths measured using an Instron testing machine. Forty extra molar crowns were roughened and treated with Clearfil Liner Bond 2 and alternative etchants, as described. A low-viscosity resin was bonded to the occlusal surfaces of these crowns, which were further demineralized and deproteinized. Field-Emission SEM examinations were carried out to evaluate the effects of different treatments on enamel surfaces. RESULTS: The mean shear bond strengths were in the range of 18.1 MPa to 25.9 MPa, without significant differences between pairs of means. The failures were predominantly of the adhesive type. The use of alternative etchants resulted in the deepest etching patterns. The use of Clearfil Liner Bond 2, according to manufacturer's directions, resulted in a poorly-defined etching pattern. Regardless of the alternative etchant used, the use of the self-etching primer did not affect the mean enamel shear bond strength.

Nondestructive tracing of migratory rhythms of intertidal benthic microalgae using in vivo chlorophyll a fluorescence1,2

Abstract: In vivo chlorophyll (Chl) a fluorescence was measured in undisturbed intertidal sediments with the purpose of tracing the vertical migratory rhythms of benthic microalgae. A pulse amplitude fluorometer, an instrument which does not require physical contact with the sample, was used, thus allowing successive measurements to be taken on the same sample without causing any type of disturbance to the sediment structure. The basis of the method is the possibility to detect changes in the Chl a concentration near the sediment surface caused by the vertical movement of the microalgae. This requires the verification of two conditions: the possibility to follow changes in the sediment Chl a content from fluorescence intensity, and a sediment photic depth smaller than the vertical distances covered by the moving microalgae. Both conditions were experimentally verified in intertidal muddy sediments of the Tagus estuary, Portugal. In vivo fluorescence was shown to vary linearly with the sediment Chl a content, and the sediment photic depth was estimated to reach 0.27 mm, a value clearly smaller than the reported depths for microalgal migrations. Sediment samples kept under in situ conditions exhibited large hourly Variations (over 400%) in the Chl a fluorescence intensity, which were closely synchronized with the daytime periods of emersion. The rhythmic fluctuations in Chl a fluorescence were confirmed further to represent microalgal migration by (1) its endogenous nature (fluorescence continued to follow diurnal and tidal cycles after removal of environmental stimuli), (2) its dependence on the vertical distribution of the microalgal population within the sediment (vertically homogenized samples failed to display fluorescence variations), and (3) the lack of significant temperature and light effects on the fluorescence emission under in situ conditions (tested in three species representative of the main groups found in the studied microphytobenthic communities—the diatom Phaeodactylum tricornutum (Bohlin), the cyanobacterium Spirulina maxima (Setch. et Gard.), and the euglenophyte Euglena granulata (Klebs) Lemm.). The results obtained indicate that, in spite of the potential concurrent effects of factors other than the Chl a concentration on the fluorescence intensity, in vivo Chl a fluorescence can be used to trace nondestructively the migratory behavior of benthic microalgae.

DYSBOT: A single-blind, randomized parallel study to determine whether any differences can be detected in the efficacy and tolerability of two formulations of botulinum toxin type A—Dysport and Botox—assuming a ratio of 4:1

Abstract: Background: Elston and Russell discovered a difference in the biological potency of the English formulation of botulinum toxin type A or BTX-A (Dysport) and the American formulation (Botox). Potency of both is expressed in LD50 mouse units, but because of assay differences, these units are not equivalent. Since the first warning by Quinn and Hallet on the clinical importance of this issue, it has been impossible to reach a consensus on the conversion factor for the potency of these formulations. Objective: To test the hypothesis that the conversion factor for the clinical potency of Dysport to Botox is approximately 4.1. DYSBOT is an acronym that results from adding “DYS” from Dysport with “BOT” from Botox. Patients and Methods: Design: A single-blind, randomized, parallel comparison. A total of 91 patients with blepharospasm or hemifacial spasm were randomized to treatment with Dysport or Botox using a fixed potency ratio of 4:1. Clinical evaluations: The patients were evaluated at baseline (day of the treatment), 1 month after treatment, and whenever the effect was judged to be fading. Objective and functional rating scales were used as quantitative measures of the change in clinical status. Adverse reactions were collected using a systematic questionnaire. Results: Using this ratio between products, both Dysport and Botox groups produced similar clinical efficacy and tolerability. For patients showing a positive response without the need of a booster, the duration of effect was 13.3 ± 5.9 weeks for the Dysport group and 11.2 ± 5.8 weeks for the Botox group. Of 48 patients, 11 (23%) needed booster treatment in the Dysport group compared with five (12%) of 43 in Botox group. Adverse events were noted in 24 (50%) of 48 patients in the Dysport group and 20 (47%) of 43 of the Botox-treated group. Conclusions: Using a 4:1 conversion ratio for Dysport and Botox, similar results were obtained for the two treatments in an appropriately powered study, suggesting that this conversion factor is a good estimate of their comparative clinical potencies.

Lagrangian Observations of Meddy Formation during A Mediterranean Undercurrent Seeding Experiment

Abstract: Mediterranean eddies (meddies) play an important role in maintaining the temperature and salinity distributions in the North Atlantic, but relatively little is known about their early life histories, including where, how often, and by what mechanism they form. A major field program, called A Mediterranean Undercurrent Seeding Experiment, has been carried out to directly observe meddy formation and the spreading pathways of Mediterranean Water into the North Atlantic. Between May 1993 and March 1994, 49 RAFOS floats were deployed sequentially in the Mediterranean Undercurrent south of Portugal and tracked acoustically for up to 11 months. The float deployments were accompanied by high-resolution XBT sections across the undercurrent. Nine meddy formation events were observed in the float trajectories, six near Cape St. Vincent, at the southwestern corner of the Iberian Peninsula, and three near the Estremadura Promontory, along the western Portuguese continental slope. Meddy formation thus occurs where the continental slope turns sharply to the right (when facing in the downstream direction of the undercurrent). After conditionally sampling the float dataset to identify floats that were well seeded in the undercurrent, the authors have estimated a meddy formation rate of 15‐20 meddies per year. The timescale for meddy formation at Cape St. Vincent was found to be 3‐7 days, shorter than previous estimates based on the volume of larger meddies. Meddies were observed to form most frequently when the speed of the Mediterranean Undercurrent was relatively fast. The meddy formation process at Cape St. Vincent resembles the conceptual model of E. A. D’Asaro, whereby anticyclonically rotating eddies are formed by separation of a frictional boundary layer (with negative relative vorticity) at a sharp corner. Comparison of the relative vorticity in the anticyclonic shear zone of the undercurrent and that of the newly formed meddies shows that much of the anticyclonic relative vorticity in meddies can be accounted for by the horizontal shear in the undercurrent. This confirms earlier work suggesting that the classical mechanism for the generation of submesoscale coherent vortices, by collapse and geostrophic adjustment of a weakly stratified fluid injected into a stratified ocean, may not be the principle mechanism at work in the formation of meddies at Cape St. Vincent.

Targeting of U2AF65 to Sites of Active Splicing in the Nucleus

Abstract: U2AF65 is an essential splicing factor that promotes binding of U2 small nuclear (sn)RNP at the pre-mRNA branchpoint. Here we describe a novel monoclonal antibody that reacts specifically with U2AF65. Using this antibody, we show that U2AF65 is diffusely distributed in the nucleoplasm with additional concentration in nuclear speckles, which represent subnuclear compartments enriched in splicing snRNPs and other splicing factors. Furthermore, transient expression assays using epitope-tagged deletion mutants of U2AF65 indicate that targeting of the protein to nuclear speckles is not affected by removing either the RNA binding domain, the RS domain, or the region required for interaction with U2AF35. The association of U2AF65 with speckles persists during mitosis, when transcription and splicing are downregulated. Moreover, U2AF65 is localized to nuclear speckles in early G1 cells that were treated with transcription inhibitors during mitosis, suggesting that the localization of U2AF65 in speckles is independent of the presence of pre-mRNA in the nucleus, which is consistent with the idea that speckles represent storage sites for inactive splicing factors. After adenovirus infection, U2AF65 redistributes from the speckles and is prefferentially detected at sites of viral transcription. By combining adenoviral infection with transient expression of deletion mutants, we show a specific requirement of the RS domain for recruitment of U2AF65 to sites of active splicing in the nucleus. This suggests that interactions involving the RS region of U2AF65 may play an important role in targeting this protein to spliceosomes in vivo.

Search for lepton flavour number violating $Z^0$ decays

Abstract: A search for lepton flavour number violating $Z^0$ decays in the channels \begin{center} $Z^0\rightarrow \mu\tau$,\\ $Z^0\rightarrow e\tau$, \\ $Z^0\rightarrow e\mu$, \\ \end{center} using the DELPHI detector with data collected during the 1991--94 LEP runs, is described. No signal was found. Upper limits at 95\% confidence level for the respective branching fractions of $1.2\times 10^{-5}$, $2.2\times 10^{-5}$, and $0.25\times 10^{-5}$, were obtained.

Relativistic calculation of the triton binding energy and its implications

Abstract: First results for the triton binding energy obtained from the relativistic spectator or Gross equation are reported. The Dirac structure of the nucleons is taken into account. Numerical results are presented for a family of realistic OBE models with off-shell scalar couplings. It is shown that these off-shell couplings improve both the fits to the two-body data and the predictions for the binding energy.

ZM241385 is an antagonist of the facilitatory responses produced by the A2A adenosine receptor agonists CGS21680 and HENECA in the rat hippocampus

Abstract: 1. In the present study, we investigated the ability of a recently introduced non-xanthine A2A receptor antagonist, ZM241385 (4-(2-[7-amino-2-(2-furyl[1,2,4]-triazolo[2,3-a[1,3,5]triazin-5-yl -aminoethyl)phenol) to displace binding of the prototypical A2A adenosine receptor agonist [3H]CGS21680 (2-[4-(2-p-carboxyethyl)phenylamino]-5'-N-ethylcarboxamidoadenosine) and to modify the facilitatory responses caused by the A2A selective agonists, CGS21680 and HENECA (2-hexynl-5'-N-ethylcarboxamidoadenosine) in rat hippocampal preparations. 2. ZM241385 was nearly equipotent to displace [3H]CGS21680 (30 nM) binding to hippocampal (Ki of 0.52 nM) and to striatal membranes (Ki of 0.35 nM), whereas HENECA was a more potent displacer of [3H]CGS21680 binding to striatal (Ki of 4.5 nM) than to hippocampal membranes (Ki of 19 nM). 3. HENECA (3-30 nM) was equipotent with CGS21680 to facilitate veratridine-evoked [3H]acetylcholine release from superfused hippocampal synaptosomes and ZM241385 (20 nM) inhibited the facilitatory effects of both HENECA (30 nM) and CGS21680 (30 nM); this antagonism was mimicked by CSC (250 nM). 4. In contrast, CGS21680 (10-30 nM) was more potent than HENECA (10-30 nM) to facilitate synaptic transmission in Schaffer fibres/CA1 pyramid synapses of hippocampal slices and the facilitatory effect of CGS21680 (10 nM) was blocked by ZM241385 (20 nM) whereas CSC (250 nM) caused a 40% attenuation of this CGS21680-induced facilitation. 5. These results indicate that ZM241385 is the first A2A antagonist with equal potency to displace [3H]CGS21680 binding to striatal and limbic regions, and with general efficiency to antagonize HENECA- or CGS21680-mediated facilitatory responses in the hippocampus.

Viscosity of toluene and benzene under high pressur

Abstract: The viscosity of toluene and benzene was measured at the temperatures of 298.15, 323.15, 348.15, and 373.15 K (ITS-90) from atmospheric pressure up to 200 MPa, by a torsionally vibrating quartz-crystal viscometer, with an estimated accuracy of 0.5%. The experimental data for each temperature were fitted with a Tait-like equation, by a non linear iterative program based on the Marquardt Levenberg method. A comparison between present data and available data from other authors, whenever possible, was made in terms of the dispersion of each data set with respect to the Tait-like equation.

Plant extracts antiviral activity against Herpes simplex virus type 1 and African swine fever virus

Abstract: Twenty-eight extracts prepared from plants used in African traditional medicine and from Rhamnus glandulosa Ait of the Portuguese flora, were screened in order to assay their antiviral activity against Herpes simplex virus type 1 (HSV-1) and African swine fever virus (ASFV) Twelve of these extracts revealed virucidal activity against HSV-1 whereas only six have the same activity against ASFV Further studies showed that thirteen of the tested extracts inhibited HSV-1 infection, some of which had a significant activity against this virus such as Senna podocarpa (Guill & Perr) Lock, Cassia sieberiana DC, Guiera senegalensis JF Gmel, Piliostigma thonningii (Schum) Milne-Redhead, Rhamnus glandulosa Ait and Uvaria chamae P Beauv Four of the twenty-one tested extracts inhibited ASFV infection

Genome replication in early mouse embryos follows a defined temporal and spatial order

Abstract: The spatial and temporal organisation of replication sites during early mouse embryogenesis was analysed using high resolution confocal and video fluorescence microscopy. The results show that distinct replication patterns occur in the transcriptionally inactive pronuclei of 1-cell embryos as well as in the transcriptionally active nuclei from 2- and 16/32-cell embryos. This indicates that specific chromatin regions are replicated at different times during S-phase and provides the first evidence that mechanisms controlling the temporal and spatial replication of DNA are already present in the haploid pronuclei of the mammalian zygote. Furthermore the data demonstrate that the male and female pronuclei in one-cell embryos replicate their genomes asynchronously. Finally, we observe changes in the dynamics of embryonic genome replication during early development which correlate with gross chromatin structure transitions detected at the electron microscope level. Taken together these results indicate that DNA synthesis in the mouse zygote follows a defined four-dimensional order which may evolve during development and differentiation.

A new method for reproducible coil positioning in transcranial magnetic stimulation mapping

Abstract: A new method is presented for mapping the motor cortex by transcranial magnetic stimulation in which the position of the stimulation coil on the scalp is measured using a 3D digitizer. The reproducibility of the method was tested by mapping 3 times the left abductor digiti minimi of 6 right-handed subjects and calculating the position of the centre of gravity (CoG), the are and volume of the individual maps. For individual maps, the coordinates of the CoG were found to be reproducible within ±3mm and the map areas and normalized volumes to within ± 20%, when the induced current flows anteriorly. Six more subjects were mapped to estimate interindividual variability of the position of the CoG. The method's ability to differentiate the cortical representation of two close muscles was successfully tested by mapping the flexor carpi radialis and the biceps brachii in another subject. Coordinates are given in a Cartesian frame of reference defined by the two tragi and the nasion. This feature will facilitate the comparison of results and their superposition on MR images.

Spatial and temporal expression of the β1D integrin during mouse development

Abstract: The beta1D protein is a recently characterized isoform of the integrin beta1 subunit that is present in cardiac and skeletal muscles. In this study, we have examined the expression of beta1D in different types of skeletal muscle and in cardiac muscle and studied its distribution during mouse development, using new monoclonal antibodies specific for beta1D. Immunoprecipitation studies revealed that, while beta1A is strongly expressed in proliferating C2C12 myoblasts, beta1D is only expressed after their differentiation to myotubes. In these myotubes, beta1D is associated with different alpha subunits, namely alpha3A, alpha5, alpha7A, or alpha7B. Initially, during embryogenesis, the alpha1A subunit is the only beta1 variant expressed in skeletal and cardiac muscle. The beta1D subunit is first detected in skeletal muscle at E17.5, whereas in cardiac muscle its expression begins around the time of birth. Later the expression of beta1A in skeletal and cardiac muscle becomes restricted to capillary cells, whereas beta1D eventually becomes the only variant expressed in adult cardiac and skeletal muscle cells. The switch from the beta1A to the beta1D subunit in cardiac muscle cells coincides with the expression of alpha7. In adults there is a distinct concentration of beta1D at the myotendinous junctions of muscle fibers and at costameres in both cardiac and skeletal muscle. In addition, beta1D is present at intercalated discs in cardiac muscle and at neuromuscular junctions in skeletal muscle cells. The amount of beta1D in different types of skeletal muscle (fast, slow, and mixed-type) was similar, but cardiac muscle expressed almost five times as much of this protein. We suggest that beta1D plays a role in the maintenance of the cytoarchitecture of mature muscle and in the functional integrity of the muscle cells.

The Importance of Shorebirds to Energy Fluxes in a Food Web of a South European Estuary

Abstract: This paper presents the results of a study on the diets and energetic needs of shorebird populations in the Tagus Estuary (Portugal). The average biomass removed by the bird populations during 1 year was estimated as 1755 kg ash-free dry weight day −1 , equivalent to a predation pressure of 103 kJ m −2 year −1 . Gulls ingested more than half of this total, with waders and ducks ingesting 15–20% each. Cormorants, egrets and flamingos each took less than 7% of the total ingested biomass, thus constituting secondary groups for energy transfers in the food web. Assuming an invertebrate production estimate of 853 kJ m −2 year −1 , the consumption efficiency of birds on the invertebrate populations was 12%. Twelve bird species took 90% of the total biomass ingested during winter by the bird populations, each specializing on one or two preferred prey species that constituted more than 75% of their ingested biomass. During winter, the Tagus bird community is characterized by its great dependence on one prey species, the bivalve Scrobicularia plana . This prey, taken either in the form of siphons or intact individuals, represented a significant percentage of the biomass taken by the bird populations (45%), and it is important for three reasons. Firstly, other bivalves taken by birds in North European estuaries are absent or occur in low densities in the Tagus. Secondly, Scrobicularia densities in the Tagus are high compared with values observed further north. Thirdly, although high densities also occur in Northern Europe, these density peaks are occasional as there is a trend for the occurrence of irregular recruitment, whereas further south, there is regular recruitment. Gulls and waders took significant percentages of bivalve siphons. This is an interesting finding, as the predation of siphons is a form of grazing with important ecological implications for energy fluxes across the estuarine ecosystem and for the prey population.

The cdk7-cyclin H-MAT1 complex associated with TFIIH is localized in coiled bodies.

Abstract: TFIIH is a general transcription factor for RNA polymerase II that in addition is involved in DNA excision repair. TFIIH is composed of eight or nine subunits and we show that at least four of them, namely cdk7, cyclin H, MAT1, and p62 are localized in the coiled body, a distinct subnuclear structure that is transcription dependent and highly enriched in small nuclear ribonucleoproteins. Although coiled bodies do not correspond to sites of transcription, in vivo incorporation of bromo-UTP shows that they are surrounded by transcription foci. Immunofluorescence analysis using antibodies directed against the essential repair factors proliferating cell nuclear antigen and XPG did not reveal labeling of the coiled body in either untreated cells or cells irradiated with UV light, arguing that coiled bodies are probably not involved in DNA repair mechanisms. The localization of cyclin H in the coiled body was predominantly detected during the G1 and S-phases of the cell cycle, whereas in G2 coiled bodies were very small or not detected. Finally, both cyclin H and cdk7 did not colocalize with P80 coilin after disruption of the coiled body, indicating that these proteins are specifically targeted to the small nuclear ribonucleoprotein-containing domain.

A new perspective on the zoogeography of the sibling mouse-eared bat species Myotis myotis and Myotis blythii: morphological, genetical and ecological evidence

Abstract: The actual geographic distribution of the two sibling mouse-eared bat species Myotis myotis and Myotis blythii, which occur widely sympatrically in the western Palaearctic region, remains largely controversial. This concerns particularly the specific attribution of marginal populations from the Mediterranean islands and from adjacent areas of North Africa and Asia, which are morphologically intermediate between continental M. myotis and M. blythii from Europe. This study attempts to clarify this question by using four different approaches: cranial morphology, external morphology, genetics and trophic ecology. The three latter methods show unambiguously that North Africa, Malta, Sardinia and Corsica are presently inhabited by monospecific populations of M. myotis. In contrast, cranial morphometrics do not yield conclusive results. These results contradict all recent studies, which attribute North African and Maltese mouse-eared bats to M. blythii and consider that Sardinia and Corsica harbour sympatric populations of the two species. As concerns south-eastem populations, doubts are also expressed about the attribution of the subspecific taxon omari which may actually refer to M. myotis instead of M. blythii. Protein electrophoresis is presently the only absolute method available for determining M. myotis and M. blythii throughout their distribution ranges. However, species identification may be approached by relying on less sophisticated morphometrical methods as presented in this study. Species-specific habitat specializations are probably responsible for the differences observed between the geographic distributions of M. myotis and M. blythii, as they provide a logical groundwork for a coherent model of speciation for these two bat species.

Magnetic stimulation in Alzheimer's disease.

Abstract: Alzheimer’s disease (AD) is a common cause of dementia in which some clinical motor abnormalities have been described. We used transcranial magnetic stimulation in order to test the hypothesis that the change in the motor cortex might cause modifications in motor excitability. Fourteen mildly to moderately affected AD patients were compared with 11 controls matched for age, height and sex. The motor evoked potential threshold value for the relaxed abductor digiti minimi was lower in the AD patients than in the control group for both left and right hemispheres (P < 0.05). No statistically significant difference was found comparing the left and the right hemispheres thresholds in each population. The mean interside threshold differences were small and not significantly different between patients and controls. The spinal motor neuron excitability, as evaluated by F/M and H/M waves amplitude ratios, showed no difference between the groups, reinforcing the motor cortex increased excitability hypothesis to explain this difference. Degeneration of inhibitory gabaergic terminals might be the basis for the increased cortical excitability in the motor cortex of the Alzheimer patients; postsynaptic changes in the GABAA receptors might also affect inhibitory gabaergic transmission. The increased excitability found by transcranial magnetic stimulation in the motor cortex is important for understanding the emergence of seizures and myoclonus in this disease.

Semantics of Architectural Connectors

Abstract: A categorical semantics is proposed for the notion of architectural connector in the style defined by Allen and Garlan which adopts notions of parameterisation similar to those developed for Abstract Data Type specification, and adapts them to formalisms for parallel program design. We show how many of the claims made in [1] can be formally substantiated, and generalised to formalisms other than CSP. Finally, we show how the categorical formalisation lends itself to useful generalisations of the notion of connector, namely through the use of multiple formalisms in the definition of the glue and the roles.

Beam bending using graded composition strained layers

Abstract: Curved crystals are commonly used to bend and extract GeV charged particle beams from high-energy accelerators. There is growing interest in multiturn extraction schemes, whereby the circulating beam makes several passages through the curved crystal, to increase the bending efficiency and also for extending their use to TeV energies. The optimum crystal length in such schemes is typically 5 mm, which imposes difficulties both in accurately aligning and bending such short lengths. This paper examines the use of Si 1−x Ge x Si graded composition strained layers to satisfy the optimum crystal dimensions and small bend angles required in such schemes. The use of Si 1−x Ge x Si graded layers to bend low-energy charged particles is experimentally demonstrated using 3 MeV protons.