979 resultados para Upper cortex


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Classic identity negative priming (NP) refers to the finding that when an object is ignored, subsequent naming responses to it are slower than when it has not been previously ignored (Tipper, S.P., 1985. The negative priming effect: inhibitory priming by ignored objects. Q. J. Exp. Psychol. 37A, 571-590). It is unclear whether this phenomenon arises due to the involvement of abstract semantic representations that the ignored object accesses automatically. Contemporary connectionist models propose a key role for the anterior temporal cortex in the representation of abstract semantic knowledge (e.g., McClelland, J.L., Rogers, T.T., 2003. The parallel distributed processing approach to semantic cognition. Nat. Rev. Neurosci. 4, 310-322), suggesting that this region should be involved during performance of the classic identity NP task if it involves semantic access. Using high-field (4 T) event-related functional magnetic resonance imaging, we observed increased BOLD responses in the left anterolateral temporal cortex including the temporal pole that was directly related to the magnitude of each individual's NP effect, supporting a semantic locus. Additional signal increases were observed in the supplementary eye fields (SEF) and left inferior parietal lobule (IPL).

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Cerebral responses to alternating periods of a control task and a selective letter generation paradigm were investigated with functional Magnetic Resonance Imaging (fMRI). Subjects selectively generated letters from four designated sets of six letters from the English language alphabet, with the instruction that they were not to produce letters in alphabetical order either forward or backward, repeat or alternate letters. Performance during this condition was compared with that of a control condition in which subjects recited the same letters in alphabetical order. Analyses revealed significant and extensive foci of activation in a number of cerebral regions including mid-dorsolateral frontal cortex, inferior frontal gyrus, precuneus, supramarginal gyrus, and cerebellum during the selective letter generation condition. These findings are discussed with respect to recent positron emission tomography (PET) and fMRI studies of verbal working memory and encoding/retrieval in episodic memory.

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Our aim was to make a quantitative comparison of the response of the different visual cortical areas to selective stimulation of the two different cone-opponent pathways [long- and medium-wavelength (L/M)- and short-wavelength (S)-cone-opponent] and the achromatic pathway under equivalent conditions. The appropriate stimulus-contrast metric for the comparison of colour and achromatic sensitivity is unknown, however, and so a secondary aim was to investigate whether equivalent fMRI responses of each cortical area are predicted by stimulus contrast matched in multiples of detection threshold that approximately equates for visibility, or direct (cone) contrast matches in which psychophysical sensitivity is uncorrected. We found that the fMRI response across the two colour and achromatic pathways is not well predicted by threshold-scaled stimuli (perceptual visibility) but is better predicted by cone contrast, particularly for area V1. Our results show that the early visual areas (V1, V2, V3, VP and hV4) all have robust responses to colour. No area showed an overall colour preference, however, until anterior to V4 where we found a ventral occipital region that has a significant preference for chromatic stimuli, indicating a functional distinction from earlier areas. We found that all of these areas have a surprisingly strong response to S-cone stimuli, at least as great as the L/M response, suggesting a relative enhancement of the S-cone cortical signal. We also identified two areas (V3A and hMT+) with a significant preference for achromatic over chromatic stimuli, indicating a functional grouping into a dorsal pathway with a strong magnocellular input.

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A combined data matrix consisting of high performance liquid chromatography–diode array detector (HPLC–DAD) and inductively coupled plasma-mass spectrometry (ICP-MS) measurements of samples from the plant roots of the Cortex moutan (CM), produced much better classification and prediction results in comparison with those obtained from either of the individual data sets. The HPLC peaks (organic components) of the CM samples, and the ICP-MS measurements (trace metal elements) were investigated with the use of principal component analysis (PCA) and the linear discriminant analysis (LDA) methods of data analysis; essentially, qualitative results suggested that discrimination of the CM samples from three different provinces was possible with the combined matrix producing best results. Another three methods, K-nearest neighbor (KNN), back-propagation artificial neural network (BP-ANN) and least squares support vector machines (LS-SVM) were applied for the classification and prediction of the samples. Again, the combined data matrix analyzed by the KNN method produced best results (100% correct; prediction set data). Additionally, multiple linear regression (MLR) was utilized to explore any relationship between the organic constituents and the metal elements of the CM samples; the extracted linear regression equations showed that the essential metals as well as some metallic pollutants were related to the organic compounds on the basis of their concentrations

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The safety, effectiveness and capabilities of therapeutic upper fibreoptic endoscopy in children undergoing therapeutic endoscopic procedures (n = 443) was studied. Therapy for gastrointestinal bleeding formed the major group (injection sclerotherapy for varices, n = 197 procedures; thermocoagulation for haemorrhagic gastritis, n = 1; and photocoaulation for Dieulafoy's disease, n = 1). Sclerotherapy was 97% effective in controlling acute bleeding and 84% effective in obliterating varices with no serious complications or deaths. Oesophageal dilatations for surgical, caustic, congenital and peptic strictures and achalasia (n = 193) were performed with no oesophageal perforations or deaths. Foreign bodies were retrieved (n = 34) with no failures or complications. Percutaneous endoscopic gastrostomy was performed (n = 11) with one failure, proceeding to an unsuccessful surgical gastrostomy. Miscellaneous procedures included endoscopic transpyloric tube placement (n = 5) and endoscopic diathermy of pyloric web (n = 1). Therapeutic fibreoptic endoscopy is therefore concluded to be safe and effective in children, replacing rigid oesophagoscopy and some traditional surgical approaches.

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An axis-parallel b-dimensional box is a Cartesian product R-1 x R-2 x ... x R-b where each R-i (for 1 <= i <= b) is a closed interval of the form [a(i), b(i)] on the real line. The boxicity of any graph G, box(G) is the minimum positive integer b such that G can be represented as the intersection graph of axis-parallel b-dimensional boxes. A b-dimensional cube is a Cartesian product R-1 x R-2 x ... x R-b, where each R-i (for 1 <= i <= b) is a closed interval of the form [a(i), a(i) + 1] on the real line. When the boxes are restricted to be axis-parallel cubes in b-dimension, the minimum dimension b required to represent the graph is called the cubicity of the graph (denoted by cub(G)). In this paper we prove that cub(G) <= inverted right perpendicularlog(2) ninverted left perpendicular box(G), where n is the number of vertices in the graph. We also show that this upper bound is tight.Some immediate consequences of the above result are listed below: 1. Planar graphs have cubicity at most 3inverted right perpendicularlog(2) ninvereted left perpendicular.2. Outer planar graphs have cubicity at most 2inverted right perpendicularlog(2) ninverted left perpendicular.3. Any graph of treewidth tw has cubicity at most (tw + 2) inverted right perpendicularlog(2) ninverted left perpendicular. Thus, chordal graphs have cubicity at most (omega + 1) inverted right erpendicularlog(2) ninverted left perpendicular and circular arc graphs have cubicity at most (2 omega + 1)inverted right perpendicularlog(2) ninverted left perpendicular, where omega is the clique number.

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Tämän pro gradu -lopputyön aiheena on englannin kielen modaalisten apuverbien ns. ydinjoukko: will, would, can, could, shall, should, may, might ja must. Semantiikan kannalta nämä apuverbit ovat erityisen kompleksisia: niiden tulkinnassa on usein huomattavaa monivivahteisuutta, vaikka perinteiset kieliopit antavat ymmärtää niillä olevan kaksi tai kolme toisistaan selkeästi erillään olevaa merkitystä. Ne asettavatkin vieraan kielen oppimisympäristössä erityisiä haasteita. Viimeaikainen kehitys korpuslingvistiikan metodeissa on tuottanut entistä tarkempia kuvauksia siitä, miten modaalisia apuverbejä nykyenglannissa käytetään ja mihin suuntaan niiden kehitys on lyhyenkin ajan sisällä kulkenut. Tämän tutkielman tavoitteena on ollut verrata näiden uusien tutkimusten tuloksia siihen todellisuuteen, jonka englannin kielen lukiotasoinen oppimateriaali Suomessa opiskelijalle tarjoaa. Lähdin siitä, että opetussuunnitelman vaatima autenttisuus ja kommunikaativisuus kieltenopetuksessa tulisi näkyä tasapuolisena modaalisten apuverbien kohteluna. Alkuperäinen hypoteesini kuitenkin oli, että siinä miten modaalisuus ilmenee autenttisessa ympäristössä ja siinä miten se esitetään oppikirjoissa, on poikkeavuuksia. Lähestymistapani tähän tutkielmaan oli korpuslähtöinen. Valitsin kahdesta lukion kirjasarjasta ne kirjat, joissa modaaliset apuverbit mainittiin eksplisiittisesti. Skannasin jokaisen neljästä eri kirjasta löytyvän (kokonaisen) tekstin ja rakensin näistä aineksista pienen korpuksen. Tästä korpuksesta hain korpusanalyyseihin tarkoitetulla ohjelmalla kaikki lauseet, joissa esiintyi modaalisia apuverbejä. Tämän jälkeen analysoin jokaisen modaalisen apuverbin semanttisesti lauseyhteydessään. Tämän analyysin tuloksena pystyin rakentamaan taulukoita ja vertailemaan tuloksia uusimpien tutkimusten tuloksiin. Tämän tutkielman perusteella poikkeavuuksia on olemassa. Yleisesti ottaen modaalisten apuverbien keskinäinen frekvenssi oli oikean suuntainen: mitään apuverbiä ei ollut käytetty merkittävästi enemmän tai vähemmän kuin mitä viimeaikaisen tutkimuksen valossa olisi suotavaa. Sen sijaan apuverbien semanttisessa jakaumassa oli paikoin suuriakin eroja siinä, mitkä merkitykset oppikirjoissa painottuivat ja mitkä taas nykyenglannissa vaikuttaisivat olevan frekvensseiltään suurempia. Erityisesti can ja must erottuivat joukosta siinä, että oppikirjojen tarjoama kuva niiden käytöstä on päinvastainen kuin mitä voisi odottaa: can-verbin käyttö painottui selvästi tarkoittamaan ’kykyä’ eikä ’mahdollisuutta’, joka nykytutkimuksen valossa on sen pääasiallinen käyttötapa. Toisaalta must tarkoitti aineistossa ylikorostuneesti ’pakkoa’, kun se useimmiten nykyään tarkoittaa yhtä usein ’johtopäätöstä’ kuin ’pakkoa’. Lisäksi ’lupaa’ pyydettiin aineistossa merkillisen harvoin. Tulosten perusteella esitän, että oppikirjojen tekijät yleisellä tasolla luopuisivat kielioppikirjojen luutuneista käsityksistä ja uskaltaisivat altistaa opiskelijat koko modaalisten apuverbien merkityskirjolle.

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Suomen koulutuspolitiikasta vastaavat viranomaiset ovat reagoineet kansainvälisten kommunikaatiotarpeiden asettamiin haasteisiin ja muuttaneet yhden lukion A-tasoisen vieraan kielen kurssin sisällön vastaamaan suullisen viestinnän tarpeita. Tutkimuksessa selvitetään, miten englannin puhestrategioita voi opettaa suomalaisille lukiolaisille ja mitä metodeja on käytettävissä puhestrategioiden oppimisen arvioimiseksi. Vastaan asettamiini kysymyksiin aikaisemman tutkimuskirjallisuuden ja englannin kielen lukio-opetuksesta keräämäni aineiston avulla. Keskeisiä elementtejä tutkielmassa ovat erityisesti pragmaattinen kompetenssi ja kolme yleisen tason puhestrategiaa (keskustelun aloittaminen, oman puheenvuoron säilyttäminen sekä keskustelun ylläpitäminen). Aineistossa on mukana 65 ensimmäisen vuosiluokan lukiolaista (luokka A ja B) Helsingistä ja Espoosta. Opetusmateriaalina on käytetty SCOTS korpusta; tarkemmin määriteltynä puhetiedosto nimeltä Conversation 20: Four secondary school girls in the North East. Tiedostossa esille tulleet, kolmeen puhestrategiaan liittyvät fraasit, sanat ja rakenteet havainnollistettiin opiskelijoille mm. AntConc - konkordanssiohjelman avulla. Opiskelijat tekivät myös kirjallisia ja suullisia harjoituksia, jotka liittyivät puhestrategioihin. Neljälle vapaaehtoiselle opiskelijalle suunnattu toinen suullinen tehtävätyyppi vapaamuotoisine keskusteluineen äänitettiin, transkriboitiin ja tuloksia arvioitiin mm. eurooppalaisen viitekehyksen avulla. Lisäksi B - luokka vastasi kyselylomakkeeseen, jossa kysyttiin heidän mielipiteitään esim. hyödyllisimmästä testioppitunnista sekä heidän osallistumishalukkuudestaan uudelle pitkän englannin kahdeksannelle syventävälle kurssille. Tutkimustulokset ovat kannustavia ja osoittavat, että puhestrategioita on mahdollista opettaa jo lukiotasolla. Vaikka tutkimuksessa käytetty lähestymistapa oli opiskelijoille osittain uusi, valtaosa heistä myönsi oppineensa uutta englannin kielen keskustelurakenteista. Lisäksi vapaaehtoisten opiskelijoiden äänitetyt ja transkriboidut keskustelut tarjoavat hyvän lähtökohdan mahdolliselle jatkotutkimukselle.

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The Mt Garnet Landcare Group commissioned a survey of landholders within the Upper Herbert and Upper Burdekin River Catchments to assess the density of native woodlands and to gauge the extent of exotic weed infestation. Twenty-four of 49 landholders responded, representing an area of nearly 500 000 ha or 47% of the total area. Dense native woodland covers 24% (>117 000 ha) of the area surveyed, while a further 30% (140 000 ha) supports moderately dense stands. The dense stands are largely confined to the highly fertile alluvial soils (26% dense woodland) and the lower fertility sandy-surfaced soils (33% or >96 000 ha). Moderate and dense infestations of exotic weeds, principally Lantana camara, occur on 54% (20 000 ha) of alluvial soils and on 13% of sandy-surfaced soils (39 000 ha), where praxelis (Praxelis clematidia) is the major weed. Basaltic soils have low levels of both dense woodland and exotic weed infestation. Some implications of the results are discussed.

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The neural basis of visual perception can be understood only when the sequence of cortical activity underlying successful recognition is known. The early steps in this processing chain, from retina to the primary visual cortex, are highly local, and the perception of more complex shapes requires integration of the local information. In Study I of this thesis, the progression from local to global visual analysis was assessed by recording cortical magnetoencephalographic (MEG) responses to arrays of elements that either did or did not form global contours. The results demonstrated two spatially and temporally distinct stages of processing: The first, emerging 70 ms after stimulus onset around the calcarine sulcus, was sensitive to local features only, whereas the second, starting at 130 ms across the occipital and posterior parietal cortices, reflected the global configuration. To explore the links between cortical activity and visual recognition, Studies II III presented subjects with recognition tasks of varying levels of difficulty. The occipito-temporal responses from 150 ms onwards were closely linked to recognition performance, in contrast to the 100-ms mid-occipital responses. The averaged responses increased gradually as a function of recognition performance, and further analysis (Study III) showed the single response strengths to be graded as well. Study IV addressed the attention dependence of the different processing stages: Occipito-temporal responses peaking around 150 ms depended on the content of the visual field (faces vs. houses), whereas the later and more sustained activity was strongly modulated by the observers attention. Hemodynamic responses paralleled the pattern of the more sustained electrophysiological responses. Study V assessed the temporal processing capacity of the human object recognition system. Above sufficient luminance, contrast and size of the object, the processing speed was not limited by such low-level factors. Taken together, these studies demonstrate several distinct stages in the cortical activation sequence underlying the object recognition chain, reflecting the level of feature integration, difficulty of recognition, and direction of attention.

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The vertical uplift resistance of two interfering rigid rough strip anchors embedded horizontally in sand at shallow depths has been examined. The analysis is performed by using an upper bound theorem o limit analysis in combination with finite elements and linear programming. It is specified that both the anchors are loaded to failure simultaneously at the same magnitude of the failure load. For different clear spacing (S) between the anchors, the magnitude of the efficiency factor (xi(gamma)) is determined. On account of interference, the magnitude of xi(gamma) is found to reduce continuously with a decrease in the spacing between the anchors. The results from the numerical analysis were found to compare reasonably well with the available theoretical data from the literature.

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In the first part of this thesis the association of different forms of sinonasal diseases and plasma concentrations of C3, C4, immunoglobulins, immunoglobulin G subclasses, C4A and C4B gene numbers were studied in 287 adult patients and 150 sex-matched adult controls. Patients were well characterized and stratified into groups using strict clinical criteria and females and males were also studied as separate groups. Severe primary antibody antibody deficiencies were rare in patients coming to sinonasal operations. Female patients had more recurrent sinusitis and other mucosal infections and males had more nasal polyposis. Upregulation of complement activity was seen in acute rhinosinusitis patients (high levels of plasma C3, C4, and complement classical pathway activity CH50) and male patients coming to sinonasal operations (high levels of plasma C3 and C4). In females, total and partial C4B deficiencies and lower levels of IgG1 and IgG3 were associated with rhinosinusitis leading to sinonasal operations. C4A deficiencies were found to predispose to severe chronic rhinosinusitis in females and males. In female patients with chronic or recurrent rhinosinusitis with nasal polyposis C4B deficiencies seem to predispose to the disease, but in males with a similar disease C4B deficiencies seem to be protective. This suggests a different pathophysiology between sexes in this form of sinonasal disease. In the second part of this thesis work 213 children coming to elective tonsillectomy were studied and compared with 155 randomly selected school children. An association with recurrent upper respiratory tract infections and hypersensitivity disorders was seen especially in children under 7 years of age. However, this association was not seen in levels of specific IgE to respiratory allergens in the same age group. Both symptomatic respiratory allergy and specific IgE to respiratory allergens became more common in boys than girls over 7 years of age. We were able to show that although both rhinoviruses and bacterial pathogens were found in the tonsils, no association between their presence and clinical forms of tonsillar disease was seen. The ability of GAS to bind complement regulators FH and C4BP did not differ between strains causing tonsillar diseases or septicemia, suggesting that other virulence mechanisms of the bacteria are more important.