1,530 research outputs found
Critical Galton-Watson processes: The maximum of total progenies within a large window
Consider a critical Galton-Watson process Z={Z_n: n=0,1,...} of index
1+alpha, alpha in (0,1]. Let S_k(j) denote the sum of the Z_n with n in the
window [k,...,k+j), and M_m(j) the maximum of the S_k with k moving in [0,m-j].
We describe the asymptotic behavior of the expectation EM_m(j) if the window
width j=j_m is such that j/m converges in [0,1] as m tends to infinity. This
will be achieved via establishing the asymptotic behavior of the tail
probabilities of M_{infinity}(j).Comment: 28 page
The Effect of Telepathic Assistance on Performance in a Visual Target-Search Task
Given the significant controversy regarding parapsychology and the study of psi phenomena, there appear to be opportunities to improve design in parapsychological experimentation through the use of more sensitive and reliable means of measurement. The current study was an attempt to introduce a design that employs time as an outcome measurement, the use of groups and individuals as opposed to just individuals, and the use of more specific and focused content through the use of problem-solving tasks, in an attempt to create a sensitive and replicable experiment in telepathy. Twenty-three undergraduate participants completed 12 trials each by finding targets in complex drawings of visual noise. A group of research assistants was employed as telepathic senders. Each subject completed both telepathically facilitated trials and control trials. Comparisons of means comparing facilitated with control conditions within subjects were conducted. Correlation between belief in psi phenomena and performance on trials was tested. Evidence was not generated for the presence of an effect of telepathic facilitation on performance nor of belief on performance. Discussion includes limitations in design, more effective use of materials, and future directions for research
MPTP-induced degeneration: interference with glutamatergic toxicity
Parkinson's disease (PD) is characterised by the progressive degeneration of nigrostriatal dopamine (DA) neurons resulting in the major symptoms of akinesia and rigidity. Although the primary cause of PD is still not known some features make this disorder a model for neurodegenerative diseases in general. It has been known for some time that symptomatic PD can be attributed to insults with symptoms occurring many years later such as post-encephalitic PD or PD following manganese poisoning. More recently, MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) has been identified as a neurotoxin selective for melanin-containing dopaminergic neurons in humans and non-human primates. The specificity of this neurotoxin and the striking clinical similarities to idiopathic PD, seen in primates, make MPTP-induced parkinsonism the most useful animal model of a neurological disease. There are numerous theoretical possibilities to interfere with both MPTP-induced neurotoxicity and the symptomatology of PD. In recent years excitatory amino acids have gained considerable interest since they can cause excitotoxic lesion of neurons under a number of pathological conditions (Olney et al., 1989; Choi, 1988). Here we summarise the present data and provide new experimental evidence indicating that MPTP-induced degeneration of dopaminergic neurons does involve glutamate-mediated toxicity. It is concluded that glutamate-mediated excitotoxicity results in the destruction of DAergic somata in the substantia nigra. Non-competitive or competitive NMDA antagonists protect nigral neurons from MPTP-induced degeneration whereas their striatal terminals still seem to degenerate
Local limit theorems for ladder moments
Let be a random walk generated by a sequence of
i.i.d. random variables and let and . Assuming that the distribution of belongs to
the domain of attraction of an -stable law we study the
asymptotic behavior of as $n\rightarrow\infty.
Terguride stimulates locomotor activity at 2 months but not 10 months after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine treatment of common marmosets
The mixed dopamine (DA) agonist/antagonist terguride acts as a DA antagonist on normosensitive receptors but shows DA agonistic properties at supersensitive DA receptors. Such a compound could offer an alternative to the treatment of Parkinson's disease with indirect or direct DA agonists. The present study compares the actions of terguride, 4-12 mg/kg i.p., in naive common marmosets with its effects in animals rendered parkinsonian by administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), 2 months or 10 months previously, in order to test its antiparkinsonian efficacy. Terguride reduced locomotor activity in naive common marmosets, similar to its effects in rodents and in line with the DA antagonistic activity of the compound. In marmosets treated with MPTP 2 months previously and exhibiting pronounced behavioural motor deficits, terguride stimulated locomotor activity, showing DA agonistic properties under these conditions. In contrast, the locomotor activity of animals that had recovered from MPTP treatment 10 months previously was not altered by terguride. It is concluded that terguride has anti-akinetic efficacy in this primate model of Parkinson's disease. In addition, terguride offers a unique opportunity to differentiate, pharmacologically, the extent of dopaminergic recovery from MPTP treatment in this primate species
The competitive NMDA antagonist CPP protects substantia nigra neurons from MPTP-induced degeneration in primates
Degeneration of nigrostriatal dopaminergic neurons is the primary histopathological feature of Parkinson's disease. The neurotoxin MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) induces a neurological syndrome in man and non-human primates very similar to idiopathic Parkinson's disease by selectively destroying dopaminergic nigrostriatal neurons. This gives rise to the hypothesis that Parkinson's disease may be caused by endogenous or environmental toxins. Endogenous excitatory amino acids (EAAs) such as L-glutamate could be involved in neurodegenerative disorders including Parkinson's disease. We report in this study that the competitive NMDA antagonist CPP (3-((+/-)-2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid) protects nigral tyrosine hydroxylase (TH) positive neurons from degeneration induced by systemic treatment with MPTP in common marmosets. This indicates that EAAs are involved in the pathophysiological cascade of MPTP-induced neuronal cell death and that EAA antagonists may offer a neuroprotective therapy for Parkinson's disease
Οutcomes for patients who are diagnosed with breast and endometrial cancer
The present study sought to determine the survival outcomes for women diagnosed with breast and endometrial cancer. Using SEER data, a population-based cohort study of women diagnosed with breast and endometrial cancer was conducted. Kaplan-Meier survival curves were created for disease-specific survival rates. A total of 2,027 women diagnosed with breast and endometrial cancer were identified. Of these, 1,296 (63.9%) developed breast cancer first and 731 (36.1%) developed endometrial cancer first. Regional lymph node involvement was significantly more common with a breast cancer diagnosis [522 (25.8%) women] compared with an endometrial cancer diagnosis [87 (4.3%) women] (P<0.05). Factors associated with decreased survival included a high tumor grade in endometrial cancer, nodal positivity and estrogen receptor-negative breast cancer (P<0.05 for each). There were 83 (4.1%) mortalities due to breast cancer, 63 (3.1%) mortalities due to endometrial cancer and 178 (8.8%) mortalities due to other causes (P<0.05). In conclusion, for women diagnosed with breast and endometrial cancer, the cumulative risk of mortality at five years following the second cancer diagnosis is nearly four times more likely to be due to breast cancer than endometrial cancer
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