Testing for Dependence in Non-Gaussian Time Series Data

This paper provides a general methodology for testing for dependence in time series data, with particular emphasis given to non-Gaussian data. A dynamic model is postulated for a continuous latent variable and the dynamic structure transferred to the non-Gaussian, possibly discrete, observations. Locally most powerful tests for various forms of dependence are derived, based on an approximate likelihood function. Invariance to the distribution adopted for the data, conditional on the latent process, is shown to hold in certain cases. The tests are applied to various financial data sets, and Monte Carlo experiments used to gauge their finite sample propertiesLatent variable model; locally most powerful tests; approximate likelihood; correlation tests; stochastic volatility tests

On pp-extensions of pp-adic fields

Let $p$ be an odd prime, and let $K$ be a $p$-adic field containing a primitive $p$-th root of unity. Let $K_{<p}$ be the maximal $p$-extension of $K$ with Galois group $\Gamma_{<p}$ of period $p$ and nilpotence class $<p$. Recent results of Abrashkin describe the ramification filtration \big{\{} \Gamma_{, and can be used to recover the structure of $\Gamma_{<p}$. The group $\Gamma_{<p}$ is described in terms of an $\mathbb{F}_p$-Lie algebra $L$ due to the classical equivalence of categories of $\mathbb{F}_p$-Lie algebras of nilpotent class $<p$, and $p$-groups of period $p$ of the same nilpotent class. In this thesis we generalise explicit calculations of Abrashkin related to the structure of $\Gamma_{<p}$

Stroke penumbra defined by an MRI-based oxygen challenge technique: 1. validation using [14C]2-deoxyglucose autoradiography

Accurate identification of ischemic penumbra will improve stroke patient selection for reperfusion therapies and clinical trials. Current magnetic resonance imaging (MRI) techniques have limitations and lack validation. Oxygen challenge T2* MRI (T2* OC) uses oxygen as a biotracer to detect tissue metabolism, with penumbra displaying the greatest T2* signal change during OC. [14C]2-deoxyglucose (2-DG) autoradiography was combined with T2* OC to determine metabolic status of T2*-defined penumbra. Permanent middle cerebral artery occlusion was induced in anesthetized male Sprague-Dawley rats (n=6). Ischemic injury and perfusion deficit were determined by diffusion- and perfusion-weighted imaging, respectively. At 147±32 minutes after stroke, T2* signal change was measured during a 5-minute 100% OC, immediately followed by 125 μCi/kg 2-DG, intravenously. Magnetic resonance images were coregistered with the corresponding autoradiograms. Regions of interest were located within ischemic core, T2*-defined penumbra, equivalent contralateral structures, and a region of hyperglycolysis. A T2* signal increase of 9.22%±3.9% (mean±s.d.) was recorded in presumed penumbra, which displayed local cerebral glucose utilization values equivalent to contralateral cortex. T2* signal change was negligible in ischemic core, 3.2%±0.78% in contralateral regions, and 1.41%±0.62% in hyperglycolytic tissue, located outside OC-defined penumbra and within the diffusion abnormality. The results support the utility of OC-MRI to detect viable penumbral tissue follow

Stroke penumbra defined by an MRI-based oxygen challenge technique: 2. Validation based on the consequences of reperfusion

Magnetic resonance imaging (MRI) with oxygen challenge (T2* OC) uses oxygen as a metabolic biotracer to define penumbral tissue based on CMRO2 and oxygen extraction fraction. Penumbra displays a greater T2* signal change during OC than surrounding tissue. Since timely restoration of cerebral blood flow (CBF) should salvage penumbra, T2* OC was tested by examining the consequences of reperfusion on T2* OC-defined penumbra. Transient ischemia (109±20 minutes) was induced in male Sprague-Dawley rats (n=8). Penumbra was identified on T2*-weighted MRI during OC. Ischemia and ischemic injury were identified on CBF and apparent diffusion coefficient maps, respectively. Reperfusion was induced and scans repeated. T2 for final infarct and T2* OC were run on day 7. T2* signal increase to OC was 3.4% in contralateral cortex and caudate nucleus and was unaffected by reperfusion. In OC-defined penumbra, T2* signal increased by 8.4%±4.1% during ischemia and returned to 3.25%±0.8% following reperfusion. Ischemic core T2* signal increase was 0.39%±0.47% during ischemia and 0.84%±1.8% on reperfusion. Penumbral CBF increased from 41.94±13 to 116.5±25 mL per 100 g per minute on reperfusion. On day 7, OC-defined penumbra gave a normal OC response and was located outside the infarct. T2* OC-defined penumbra recovered when CBF was restored, providing further validation of the utility of T2* OC for acute stroke management

Potential use of oxygen as a metabolic biosensor in combination with T2*-weighted MRI to define the ischemic penumbra

We describe a novel magnetic resonance imaging technique for detecting metabolism indirectly through changes in oxyhemoglobin:deoxyhemoglobin ratios and T2* signal change during ‘oxygen challenge’ (OC, 5 mins 100% O2). During OC, T2* increase reflects O2 binding to deoxyhemoglobin, which is formed when metabolizing tissues take up oxygen. Here OC has been applied to identify tissue metabolism within the ischemic brain. Permanent middle cerebral artery occlusion was induced in rats. In series 1 scanning (n=5), diffusion-weighted imaging (DWI) was performed, followed by echo-planar T2* acquired during OC and perfusion-weighted imaging (PWI, arterial spin labeling). Oxygen challenge induced a T2* signal increase of 1.8%, 3.7%, and 0.24% in the contralateral cortex, ipsilateral cortex within the PWI/DWI mismatch zone, and ischemic core, respectively. T2* and apparent diffusion coefficient (ADC) map coregistration revealed that the T2* signal increase extended into the ADC lesion (3.4%). In series 2 (n=5), FLASH T2* and ADC maps coregistered with histology revealed a T2* signal increase of 4.9% in the histologically defined border zone (55% normal neuronal morphology, located within the ADC lesion boundary) compared with a 0.7% increase in the cortical ischemic core (92% neuronal ischemic cell change, core ADC lesion). Oxygen challenge has potential clinical utility and, by distinguishing metabolically active and inactive tissues within hypoperfused regions, could provide a more precise assessment of penumbra

Arm Pain Trial : Study materials

Publisher PD

Maintained physical activity and physiotherapy in the management of distal arm pain: A randomised controlled trial

Objectives: The epidemiology of distal arm pain and back pain are similar. However, management differs considerably: for back pain, rest is discouraged, whereas patients with distal arm pain are commonly advised to rest and referred to physiotherapy. We hypothesised that remaining active would reduce long-term disability and that fast-track physiotherapy would be superior to physiotherapy after time on a waiting list.Methods: Adults referred to community-based physiotherapy with distal arm pain were randomised to: advice to remain active while awaiting physiotherapy (typically delivered after 6-8 weeks); advice to rest while awaiting physiotherapy, or immediate treatment. Intention-to-treat analysis determined whether the probability of recovery at 26 weeks was greater among the active advice group, compared with those advised to rest and/or among those receiving immediate versus usually timed physiotherapy.Results: 538 of 1663 patients invited between February 2012 and February 2014 were randomised (active=178; rest=182; immediate physiotherapy=178). 81% provided primary outcome data, and complete recovery was reported by 60 (44%), 46 (32%) and 53 (35%). Those advised to rest experienced a lower probability of recovery (OR: 0.54; 95% CI 0.32 to 0.90) versus advice to remain active. However, there was no benefit of immediate physiotherapy (0.64; 95% CI 0.39 to 1.07).Conclusions: Among patients awaiting physiotherapy for distal arm pain, advice to remain active results in better 26-week functional outcome, compared with advice to rest. Also, immediate physiotherapy confers no additional benefit in terms of disability, compared with physiotherapy delivered after 6-8 weeks waiting time. These findings question current guidance for the management of distal arm pain

Maintained physical activity and physiotherapy in the management of distal upper limb pain – a protocol for a randomised controlled trial (the arm pain trial)

&lt;b&gt;Background&lt;/b&gt;&lt;p&gt;&lt;/p&gt; Distal upper limb pain (pain affecting the elbow, forearm, wrist, or hand) can be non-specific, or can arise from specific musculoskeletal disorders. It is clinically important and costly, the best approach to clinical management is unclear. Physiotherapy is the standard treatment and, while awaiting treatment, advice is often given to rest and avoid strenuous activities, but there is no evidence base to support these strategies. This paper describes the protocol of a randomised controlled trial to determine, among patients awaiting physiotherapy for distal arm pain, (a) whether advice to remain active and maintain usual activities results in a long-term reduction in arm pain and disability, compared with advice to rest; and (b) whether immediate physiotherapy results in a long-term reduction in arm pain and disability, compared with physiotherapy delivered after a seven week waiting list period.&lt;p&gt;&lt;/p&gt; &lt;b&gt;Methods/Design&lt;/b&gt;&lt;p&gt;&lt;/p&gt; Between January 2012 and January 2014, new referrals to 14 out-patient physiotherapy departments were screened for potential eligibility. Eligible and consenting patients were randomly allocated to one of the following three groups in equal numbers: 1) advice to remain active, 2) advice to rest, 3) immediate physiotherapy. Patients were and followed up at 6, 13, and 26 weeks post-randomisation by self-complete postal questionnaire and, at six weeks, patients who had not received physiotherapy were offered it at this time. The primary outcome is the proportion of patients free of disability at 26 weeks, as determined by the modified DASH (Disabilities of the Arm, Shoulder and Hand) questionnaire.&lt;p&gt;&lt;/p&gt; We hypothesise (a) that advice to maintain usual activities while awaiting physiotherapy will be superior than advice to rest the arm; and (b) that fast-track physiotherapy will be superior to normal (waiting list) physiotherapy. These hypotheses will be examined using an intention-to-treat analysis.&lt;p&gt;&lt;/p&gt; &lt;b&gt;Discussion&lt;/b&gt;&lt;p&gt;&lt;/p&gt; Results from this trial will contribute to the evidence base underpinning the clinical management of patients with distal upper limb pain, and in particular, will provide guidance on whether they should be advised to rest the arm or remain active within the limits imposed by their symptoms

The Lantern Vol. 58, No. 2, Summer 1991

• We All Fall Up • Clerical Nightmares • The Brass Bed • Mon Amour • The Lady of J. Alfred Prufrock • Forbidden Places • Edge of the Dance • Crystal World • Saturday, July 12, 1978, 4:59 pm • Of You I Think • Just Another Statistic • A $16 Word in a$4.99 Trashcan • Souvenir • The Jester • Against a Rock • I Wish I Were a Fish • Too Small, Too Weak • Somewheres in N.Y.C. • Stuck Up • Patterns • I Should Tell You Now • Me, Tommy, and Miss May • Two Hands • All-Natural, Organically Grown Macadamia Butter • Irony of a Suburban Deathhttps://digitalcommons.ursinus.edu/lantern/1138/thumbnail.jp