Long Memory and FIGARCH Models for Daily and High Frequency Commodity Prices

Daily futures returns on six important commodities are found to be well described as FIGARCH fractionally integrated volatility processes, with small departures from the martingale in mean property. The paper also analyzes several years of high frequency intra day commodity futures returns and finds very similar long memory in volatility features at this higher frequency level. Semi parametric Local Whittle estimation of the long memory parameter supports the conclusions. Estimating the long memory parameter across many different data sampling frequencies provides consistent estimates of the long memory parameter, suggesting that the series are self-similar. The results have important implications for future empirical work using commodity price and returns data.Commodity returns, Futures markets, Long memory, FIGARCH

Cigarette Smoking after Aerobic Exercise: The Unfavorable Impacts on Vascular Function

It is well-accepted that vascular dysfunction plays a key role in the pathophysiology of cardiovascular diseases. Although vascular dysfunction is multi-faceted, exercise is a commonly recommended prophylactic strategy to preserve vascular function. We and others have shown that exercise training can elicit beneficial effects on vascular function (e.g., blood pressure and conduit artery function) in healthy and clinical populations1-4. In fact, indices of vascular function are enhanced shortly after acute exercise5,6, suggesting that the postexercise recovery period may be a crucial component for facilitating long-term vascular adaptations7. Poor habits may be detrimental to this recovery window, such as cigarette smoking. Cigarette smoking is considered a common modifiable risk factor for cardiovascular diseases and is associated with arterial stiffness and endothelial dysfunction8,9. Since exercise is often recommended to individuals with cardiovascular risk factors to prevent disease, it is imperative to understand how smoking can impact acute exercise recovery. Previous studies have investigated cigarette smoking prior to acute exercise and revealed that this can impair normal vascular and exercise pressor responses, thus inducing greater cardiac and arterial strain10-12. However, until recently, the impacts of cigarette smoking on hemodynamics and conduit artery function during recovery after aerobic exercise have not been explored. In this issue of The Korean Journal of Sports Medicine, Cho et al.13 investigated the effects of cigarette smoking on blood pressure and conduit artery function during recovery after an acute bout of moderate-intensity aerobic exercise

Microvascular Dysfunction in Peripheral Artery Disease: Is Heat Therapy a Viable Treatment?

Peripheral artery disease (PAD) is characterized by the development of atherosclerotic plaques in the lower-body conduit arteries. PAD is commonly accompanied by microvascular disease, which may result in poor wound healing, plantar ulcer development, and subsequent limb amputation. Understanding the mechanisms underlying the development of plantar ulcers is a critical step in the development of adequate treatment options for patients with PAD. Skin is classified into two major components: glabrous and non-glabrous. These skin types have unique microcirculation characteristics, making it important to differentiate between the two when investigating mechanisms for plantar ulcer development in PAD. There is evidence for a microcirculation compensatory mechanism in PAD. This is evident by the maintenance of basal microcirculation perfusion and capillary filling pressure despite a reduced pressure differential beyond an occlusion in non-critical limb ischemia PAD. The major mechanism for this compensatory system seems to be progressive vasodilation of the arterial network below an occlusion. Recently, heat therapies have emerged as novel treatment options for attenuating the progression of PAD. Heat therapies are capable of stimulating the cardiovascular system, which may lead to beneficial adaptations that may ultimately reduce fatigue during walking in PAD. Early work in this area has shown that full-body heating is capable of generating an acute cardiovascular response, similar to exercise, which has been suggested as the most efficient treatment modality and may generate adaptations with chronic exposure. Heat therapies may emerge as a conservative treatment option capable of attenuating the progression of PAD and ultimately impeding the development of plantar ulcers

Impacts of aquatic walking on arterial stiffness, exercise tolerance, and physical function in patients with peripheral artery disease: a randomized clinical trial

Peripheral artery disease (PAD) is an atherosclerotic disease that is associated with attenuated vascular function, cardiorespiratory capacity, physical function, and muscular strength. It is essential to combat these negative effects on health by incorporating lifestyle interventions to slow disease progression, such as exercise. We sought to examine the effects of aquatic walking exercise on cardiovascular function, cardiorespiratory capacity [maximal volume of oxygen consumption (V̇o2max)], exercise tolerance [6-min walking distance (6MWD)], physical function, muscular strength, and body composition in patients with PAD. Patients with PAD (n = 72) were recruited and randomly assigned to a 12-wk aquatic walking training group (AQ, n = 35) or a control group (CON, n = 37). The AQ group performed walking and leg exercises in waist-to-chest-deep water. Leg arterial stiffness [femoral-to-ankle pulse wave velocity (legPWV)], heart rate (HR), blood pressure (BP), ankle-to-brachial index (ABI), V̇o2max, 6MWD, physical function, muscular strength, body composition, resting metabolic rate (RMR), and flexibility were measured before and after 12 wk. There were significant group × time interactions (P \u3c 0.05) after 12 wk for legPWV and HR, which significantly decreased (P \u3c 0.05) in AQ, and V̇o2max, 6MWD, physical function, and muscular strength, which significantly increased (P \u3c 0.05) in AQ, compared with no changes in CON. There were no significant differences (P \u3e 0.05) for BP, ABI, RMR, or flexibility after 12 wk. Interestingly, there was relatively high adherence (84%) to the aquatic walking exercise program in this population. These results suggest that aquatic walking exercise is an effective therapy to reduce arterial stiffness and resting HR and improve cardiorespiratory capacity, exercise tolerance, physical function, and muscular strength in patients with PAD

Origin and Characterization of Multipotential Mesenchymal Stem Cells Derived from Adult Human Trabecular Bone

Much of the knowledge regarding the regulatory pathways for adult stem cell self-renewal and differentiation has been obtained from the results of in vitro cultures. However, it is unclear if adult stem cells are controlled in the same way under physiological conditions. We examined this issue with respect to the migration of stem cells to tissue injury and how switch from a migratory state to one of proliferation wherein they participate in development. Building on our previous identification of multipotent stem cells in trabecular bone, we have examined the in vitro behavior of these cells within the bone milieu. We found that cell proliferation is inhibited within the trabecular bone niche as cells migrate out of the trabecular bone prior to proliferation. Additionally, multiple cell types were detected in adult trabecular bone, including osteoblasts, osteoclasts, endothelial cells, and Stro-1-positive mesenchymal stem cells. Furthermore, we demonstrated that Stro-1-positive cells migrated out of their native bone niche to generate multipotential stem and progenitor cells during in vitro culture. We conclude that self-renewal and differentiation of adult stem cells in connective tissues are tightly controlled and separately orchestrated processes. A regulatory network of extrinsic factors and intrinsic signals acts to stimulate the exit of stem cells from their niche so that they can localize to sites of wound healing, where they participate in development after functional differentiation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63409/1/scd.2005.14.712.pd

Body mass-normalized moderate dose of dietary nitrate intake improves endothelial function and walking capacity in patients with peripheral artery disease

Peripheral artery disease (PAD) is characterized by the accumulation of atherosclerotic plaques in the lower extremity conduit arteries, which impairs blood flow and walking capacity. Dietary nitrate has been used to reduce blood pressure (BP) and improve walking capacity in PAD. However, a standardized dose for PAD has not been determined. Therefore, we sought to determine the effects of a body mass-normalized moderate dose of nitrate (0.11 mmol nitrate/kg) as beetroot juice on serum nitrate/nitrite, vascular function, walking capacity, and tissue oxygen utilization capacity in patients with PAD. A total of 11 patients with PAD received either nitrate supplement or placebo in a randomized crossover design. Total serum nitrate/nitrite, resting BP, brachial and popliteal artery endothelial function (flow-mediated dilation, FMD), arterial stiffness (pulse-wave velocity, PWV), augmentation index (AIx), maximal walking distance and time, claudication onset time, and skeletal muscle oxygen utilization were measured pre- and postnitrate and placebo intake. There were significant group × time interactions (P \u3c 0.05) for serum nitrate/nitrite, FMD, BP, walking distance and time, and skeletal muscle oxygen utilization. The nitrate group showed significantly increased serum nitrate/nitrite (Δ1.32 μM), increased brachial and popliteal FMD (Δ1.3% and Δ1.7%, respectively), reduced peripheral and central systolic BP (Δ−4.7 mmHg and Δ−8.2 mmHg, respectively), increased maximal walking distance (Δ92.7 m) and time (Δ56.3 s), and reduced deoxygenated hemoglobin during walking. There were no changes in PWV, AIx, or claudication (P \u3e 0.05). These results indicate that a body-mass normalized moderate dose of nitrate may be effective and safe for reducing BP, improving endothelial function, and improving walking capacity in patients with PAD

A 0.5 μm Thick Polysilicon Schottky Diode with Rectification Ratio of 10^6

Polycrystalline Si films, 0.5-mm thick, were obtained as a result of metal-induced growth by sputtering from a Si target on 25 nm thick Ni prelayers at 525 °C. Silicon grew heteroepitaxially on the NiSi2 layer formed due to the reaction between the sputtered Si atoms and Ni. Schottky diodes were fabricated on the Si films by deposition of a Schottky metal on the front surface of the film while Ni disilicide provided an intimate ohmic contact at the back. A Pd/n-Si diode using an n-Si film annealed for 2 h at 700 °C in forming gas demonstrated a rectification ratio of 106, while an as-deposited p-Si film provided an Al/p-Si diode with rectification of five orders of magnitude. Schottky barrier properties are briefly discussed

Effects of heated water-based versus land-based exercise training on vascular function in individuals with peripheral artery disease

Peripheral artery disease (PAD) is an atherosclerotic disease that is associated with poor vascular function, walking impairment, and reduced quality of life. Land-based exercise therapy (LBET) is frequently recommended to improve walking and reduce symptoms. Recently, evidence has suggested that heated-water exercise therapy (HWET) is an effective intervention for PAD. However, the efficacy of LBET versus HWET in PAD patients had not been elucidated. Therefore, we sought to compare effects of LBET with HWET on cardiovascular function, exercise tolerance, physical function, and body composition in PAD patients. PAD patients (n = 53) were recruited and randomly assigned to a LBET group (n = 25) or HWET group (n = 28). The LBET group performed treadmill walking, whereas the HWET group performed walking in heated water for 12 wk. Leg (legPWV) and brachial-to-ankle arterial stiffness (baPWV), blood pressure (BP), ankle-brachial index (ABI), 6-min walking distance (6MWD), claudication onset time (COT), physical function, and body composition were assessed before and after 12 wk. There were significant group-by-time interactions (P \u3c 0.05) for legPWV, BP, 6MWD, COT, body composition, and resting metabolic rate (RMR). Both groups significantly reduced (P \u3c 0.05) legPWV, BP, and body fat percentage, and HWET measures were significantly lower than LBET measures. Both groups significantly increased 6MWD, COT, and RMR, and HWET group measures were significantly greater than LBET measures. A time effect was noted for baPWV reduction in both groups (P \u3c 0.05). These results suggest that both LBET and HWET improve cardiovascular function, exercise tolerance, and body composition, and HWET showed considerably greater improvements compared with LBET in patients with PAD

Impacts of dietary nitrate on endothelial function, arterial stiffness, and systemic vascular pressure in peripheral arterial disease

Peripheral arterial disease (PAD) is the manifestation of atherosclerotic plaque in the larger arteries of the legs, which results in impaired blood flow to the lower extremities. Markers of vascular health, including endothelial function and arterial stiffness, have been shown to be attenuated in PAD. Purpose: We sought to examine the effects of a nitrate supplement (body mass-normalized dosage of beetroot juice) on vascular function measurements such as endothelial function, arterial stiffness, and central and peripheral blood pressure in patients with PAD. We hypothesized that acute intake of a nitrate supplement would improve vascular function. Methods: PAD patients (stage II-III, n=2, age around 73) had vascular measurements taken pre and post-beetroot juice ingestion including heart rate (HR), blood pressure (BP), endothelial function, arterial stiffness, and central pressure analysis. Results: Following nitrate ingestion, HR increased (Δ0.5 bpm) along with decreases in peripheral BP (Δ-9/-10 mmHg) and central BP (Δ-18/-4 mmHg). Endothelial function increased (Δ3.75%), carotid-to-radial pulse wave velocity decreased (Δ0.25 m/s), and augmentation index increased (Δ30.1%) after nitrate intake. Measurements of deceleration time increased (Δ49.5ms) and augmented pressure decreased (Δ-5 mmHg) after nitrate ingestion. Conclusion: Acute intake of a nitrate supplement may potentially be a useful therapeutic treatment to improve both central and peripheral vascular function which may be explained by increased endothelial dependent and independent vasodilatory mechanisms. However, this is a pilot study with two patients; therefore, future study is warranted with a bigger sample size to examine impacts of nitrate ingestion on vascular function and to further extrapolate our findings to patients with PAD

Effect of oxygen minimum zone formation on communities of marine protists

Author Posting. © The Author(s), 2012. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in The ISME Journal 6 (2012): 1586–1601, doi:10.1038/ismej.2012.7.Changes in ocean temperature and circulation patterns compounded by human activities are leading to oxygen minimum zone expansion with concomitant alteration in nutrient and climate active trace gas cycling. Here, we report the response of microbial eukaryote populations to seasonal changes in water column oxygen-deficiency using Saanich Inlet, a seasonally anoxic fjord on the coast of Vancouver Island British Columbia, as a model ecosystem. We combine small subunit ribosomal RNA gene sequencing approaches with multivariate statistical methods to reveal shifts in operational taxonomic units during successive stages of seasonal stratification and renewal. A meta-analysis is used to identify common and unique patterns of community composition between Saanich Inlet and the anoxic/sulfidic Cariaco Basin (Venezuela) and Framvaren Fjord (Norway) to show shared and unique responses of microbial eukaryotes to oxygen and sulfide in these three environments. Our analyses also reveal temporal fluctuations in rare populations of microbial eukaryotes, particularly anaerobic ciliates, that may be of significant importance to the biogeochemical cycling of methane in oxygen minimum zones.This work was performed under the auspices of the US Department of Energy's Office of Science, Biological and Environmental Research Program, and by the University of California, Lawrence Berkeley National Laboratory, Lawrence Livermore National Laboratory under Contract No., and Los Alamos National Laboratory (Contract No. DE-AC02-05CH11231, DE-AC52-07NA27344, DE-AC02-06NA25396), the Natural Sciences and Engineering Research Council (NSERC) of Canada 328256-07 and STPSC 356988, Canada Foundation for Innovation (CFI) 17444; Canadian Institute for Advanced Research (CIFAR), NSF MCB-0348407 to VE, NSF Center for Deep Energy Biosphere Investigations, and the Center for Bioinorganic Chemistry (CEBIC).2012-09-0