2-D(Two-dimensional) isotropic negative refractive
index (NRI) is explicitly realized via the orthogonal
signal and coupling standing-wave fields coupling the Ntype
four-level atomic system. Under ...some key parameters
of the dense vapour media, the atomic system exhibits
isotropic NRI with simultaneous negative permittivity
and permeability (i.e. left-handedness) in the 2-D x-y
plane. Compared with other 2-D NRI schemes, the coherent
atomic vapour media in our scheme may be an ideal
2-D isotropic NRI candidate and has some potential advantages,
significance or applications in the further investigation.
Background Left-handedness was historically considered a disability and a social stigma, and teachers would make efforts to suppress it in their students. Little data are available on the impact of ...left-handedness on surgical training. This report reviews available data on this subject. Methods We did systematic electronic and manual literature searches using a predetermined strategy independently by 2 investigators, 1 left- and 1 right-handed, to identify reports on surgical training and left-handedness. Results The review revealed 19 studies on the subject of left-handedness and surgical training. Data were heterogeneous and based mostly on surveys. Left-handedness produced anxiety in residents and their trainers. There was a lack of mentoring on laterality. Surgical instruments, both conventional and laparoscopic, are not adapted to left-handed use and require ambilaterality training from the resident. There is significant pressure to change hand laterality during training. However, left-handedness might present an advantage in operations involving situs inversus or left lower limb operations. Conclusions Left-handedness is a challenge both for the trainee and the trainer in surgery. Early laterality-related mentoring in medical school and during surgical residency with provision of left-handed instruments might reduce the inconveniences of left-handed surgeons learning.
Life span studies have shown that the population percentage of left-handers diminishes steadily, so that they are drastically underrepresented in the oldest age groups. Data are reviewed that ...indicate that this population trend is due to the reduced longevity of left-handers. Some of the elevated risk for sinistrals is apparently due to environmental factors that elevate their accident susceptibility. Further evidence suggests that left-handedness may be a marker for birth stress related neuropathy, developmental delays and irregularities, and deficiencies in the immune system due to the intrauterine hormonal environment. Some statistical and physiological factors that may cause left-handedness to be selectively associated with earlier mortality are also presented.
Handedness and Professional Tennis Holtzen, David W.
International journal of neuroscience,
01/2000, Letnik:
105, Številka:
1-4
Journal Article
Recenzirano
Based on the hypothesis that as a group left-handed (LH) people have better developed right hemispheres and therefore have better developed motor, attentional, and spatial functions than right-handed ...people (Geschwind, 1982; Geschwind and Galaburda, 1985a, 1985b; Nass and Gazzaniga, 1987), several studies have examined a possible association between left-handedness and superior tennis ability (cited in Annett, 1985; Azemar et al. 1983; Wood and Aggleton, 1989). The conflicting findings of these studies are due to flawed research designs, very limited data, and inadequate data analyses. In this study an estimated population rate of left-handedness for racket use (8.1%) was compared with rates found among professional tennis players; and highly successful competitors over a 32-year period were analyzed for handedness frequency. Results revealed that from 1968 through 1999 LH competitors were significantly over-represented among top ranking players (World Number One and Top Ten) and among Grand Slam finalists, including champions. Rates of left-handedness ranged from two to five times higher than expected in these highly successful players. However, no difference was found in the rate of left-handedness for racket use among male (N = 1.904; LH = 6.98%) or female (N = 533; LH = 7.69%) professional tennis players compared to the general population. These findings indirectly support the notion that LH people have neuroanatomically-based advantages in performing certain neurocognitive tasks, such as visuospatial and gross (whole body) visuormotor tasks. The present findings are also consistent with a nature/nurture model of cortical development and functioning (Casey, 1996).
The Afrikaner and schizophrenia : a genetic study An overview is given on the genetics of schizophrenia in an Afrikaner founder population. This research has been done over a period of ten years. ...Founder populations hold tremendous promise for mapping genes for complex traits, as they offer less genetic and environmental heterogeneity and greater potential for genealogical research. Not all founder populations are equally valuable, however. The Afrikaner population meets several criteria that make it an ideal population for mapping complex traits. These include founding by a small number of initial founders that likely allowed for a relatively restricted set of mutations and a large current population size that allows identification of a sufficient number of cases. Since a large number of patients was traced to an original founder couple, the genealogical data of the research support the hypothesis that a substantial portion of the schizophrenia cases the researchers have identified will share the same or a small number of susceptibility alleles. Results further show that genetic variation at the 22q11 locus enhances the risk to develop schizophrenia. More than one gene in this region can independently or synergistically increase the risk of schizophrenia in nondeleted patients. In three independent samples, evidence was provided for a contribution of the PRODH / DGCR6 locus in 22q11 associated schizophrenia. One of these samples was from South Africa as part of an ongoing collection of schizophrenia patients of Afrikaner origin. An unusual pattern of PRODH2 gene variation that mimics the sequence of a linked pseudogene was uncovered. Several of the pseudogene-like variants identified, resulted in missense changes at conserved residues and may prevent synthesis of a fully functional enzyme. The results have implications for understanding the genetic basis of the 22q11-associated psychiatric phenotype and provide further insight into the genomic instability of this region. It was shown in an independent sample of Afrikaner schizophrenia patients that the frequency of 22q11 deletion syndrome was 2%, as suggested in earlier studies. Early deviant behaviour before 10 years of age was the most important factor related to the onset of illness. Early deviant childhood behaviour was grouped into three clusters: social functioning impairment cluster, mood / anxiety cluster and cognitive impairment cluster. Some of these factors are important in male schizophrenia patients and may be used as endophenotypic markers. The LRRTM1 gene is implicated in the paternal transmission of schizophrenia. This gene may be implicated in the development of specific forebrain structures. It influences neuronal differentiation and connections. Male users of cannabis suffering from schizophrenia; with prominent early deviant behaviour have the lowest age of onset of illness, namely 18.4 years. Approximately half of the male schizophrenia patients and a quarter of the female schizophrenia patients used or abused cannabis. These figures are high and make cannabis use / abuse an important part of the management strategy of these patients. It was stated that in male patients with a specific subtype of schizophrenia (where early deviant behaviour was present) the use of cannabis triggers an illness with earlier onset and a poor prognosis. The prevalence of obsessive-compulsive disorder and obsessive-compulsive symptoms in Afrikaner patients suffering from schizophrenia was 13.25%. This finding differs from those in another ethnic group in South Africa suggesting the possible role of genetic and cultural factors in the prevalence of co-morbid OCD / OCS in this patient population. The most common obsession reported was contamination followed by religious obsession. The most common compulsion was checking behaviour. Clinical characteristics of Afrikaner schizophrenia and schizo-affective disorder patients with and without co-morbid OCD / OCS are the same; both groups were associated with significant psychopathology and a poor prognosis. Die artikel gee 'n oorsig oor navorsingbevindings die afgelope tien jaar oor die genetika van skisofrenie in die Afrikaner as 'n stigtersbevolking. Die genealogiese data in die studie steun die hipotese dat 'n aansienlike deel van die skisofrenie-pasiënte wat geïdentifiseer is, dieselfde of 'n klein aantal vatbaarheid-allele deel, omdat 'n groot aantal pasiënte teruggespoor kan word na 'n stigtersegpaar. Die resultate toon verder dat genetiese variase op die 22q11-lokus die risiko om die siekte te ontwikkel verhoog. Meer as een geen op hierdie gebied kan onafhanklik of sinergisties die risiko in pasiënte, waar die geen nie uitgewis is nie, verhoog. Die studie het ook, in 'n onafhanklike steekproef, bevestig dat die frekwensie van die 22q11-uitwissingsindroom in volwasse Kaukasiese skisofreniese pasiënte ongeveer 2% is, soos voorheen voorgestel. Vroeë afwykende gedrag is die belangrikste faktor wat die ouderdom van aanvang van siekte bepaal veral in manlike pasiënte met skisofrenie en is 'n moontlike endofenotipe merker. Die geen LRHTM1 (leusienryk-herhaaltransmembraan-neuronaal-1) word geïmpliseer by vaderlike oordrag van skisofrenie en skisoaffektiewe versteuring. Waarskynlik speel die geen 'n rol gedurende die ontwikkeling van spesifieke voorbreinstrukture, deur neuronale differensiasie en verbinding te beïnvloed. Manlike verbruikers van cannabis met ernstige vroeë afwykende gedrag het die laagste gemiddelde ouderdom van aanvang van siekte gehad, naamlik 18.4 jaar. Dit word geïnterpreteer dat in mans met 'n spesifieke subtipe van skisofrenie (waar vroeë afwykende gedrag teenwoordig is) cannabis die aanvang van siekte sal ontlont op 'n vroeër ouderdom en die psigose het gevolglik 'n swak prognose. Die voorkoms van obsessief-kompulsiewe versteuring en obsessief-kompulsiewe simptome in Afrikaner pasiënte met skisofrenie was 13.25%. Die algemeenste gerapporteerde obsessie was kontaminasie, gevolg deur geloofsobsessies. Die algemeenste kompulsie was nagaan-gedrag.
Left-handers were more likely to report having an injury requiring medical attention during the last two years. Relative risk was highest for left-handed males when driving motor vehicles. Regardless ...of handedness, males had slightly higher relative risks of injury than females. (Abstract amended)
Male and female left-handed writers were subdivided according to familial sinistrality and strength of handedness. Performance in computerised reaction time and in maze tests was assessed by skill, ...solving strategy and laterality indices. Verbal ability was assessed by a vocabulary test. (Abstract amended)
The development of laterality Perelle, I B; Ehrman, L
Behavioral science,
October 1983, Letnik:
28, Številka:
4
Journal Article
Recenzirano
Experimental data, primarily from experiments with Drosophila, and observational data, primarily from human beings, are presented to show if their is a genetic basis for laterality. The evidence was ...found to be inconclusive. It is proposed that there for three etiologies of lefthandedness in human beings: pathological, natural, and learned.
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