Bike Athlete Performance

Faculty reflection on VCU Great Bike Race Book course. Course Description: This track will focus on nutritional and training practices of cyclists competing in the UCI Worlds. YouTube Videos referenced in reflection: VCU Exercise Science: Christian Vande Velde Interview VCU Exercise Science - Sports Nutritionist Dr Janet Rankin Interview Fuel for a 5 Hour Ride Assignment 3: My Musette Assignment 4: Bike Athlete Performance VCU Exercise Science: Professional Cyclist Evie Stevens Intervie

Time Course of Vascular Function changes Following an Acute Maximal Exercise Bout in Obese and Normal Weight Males

One of the earliest sub-clinical stages associated with atherosclerosis is endothelial dysfunction (ED), which has been shown to predict future cardiovascular events. Chronic exercise is thought to improve endothelium-dependent vasodilation; however, few studies have evaluated the effects of acute exercise on vascular function (VF). Moreover, studies evaluating ED following an exercise training program lack a standardized time frame in which to measure VF. Although most studies require subjects to abstain from exercise for 24 hours prior to any VF measure, no study to date has assessed VF longer than 24 hours after the cessation of exercise. Additionally, no studies have compared VF responses in obese and non-obese individuals following acute exercise. Purpose: Therefore, the purpose of this study was to evaluate VF, as determined by the assessment of forearm blood flow (FBF) and vascular reactivity (VR) before and up to 48 hours after a single bout of maximal exercise in obese and non-obese males. Methods: Twelve obese (37.0 ± 1.1 kg/m2) and twelve non-obese (21.9 ± 0.3 kg/m2) males volunteered to participate. FBF was assessed before and during reactive hyperemia (RH). FBF measures were obtained prior to (PRE-E), immediately after (POST-E), and at 1 (POST-1), 2 (POST-2), 24 (POST-24), and 48 (POST-48) hours after exercise. Total excess flow, calculated as the difference between baseline FBF and FBF during RH, was used as an indicator of VR. Blood samples were also obtained at each time point to evaluate the response of interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α), which are potential modifiers of VF. Results: Baseline FBF and FBF during RH were significantly (P \u3c 0.05) increased in both groups POST-E before returning to baseline values by POST-1. VR was enhanced in both groups POST-E, although the magnitude of change was greater in non-obese males. VR was significantly (P \u3c 0.05) increased in non-obese males POST-E and was not significantly (P \u3c 0.05) reduced until POST-48. Concentrations of IL-6 and TNF-α were unchanged in response to exercise in non-obese and obese males. Conclusions: An acute bout of maximal exercise significantly increased forearm endothelium-dependent vasodilation in non-obese and obese males. Additionally, an increased reactive vasodilation was observed only in non-obese males following exercise. These results also suggest that in non-obese males, measurements used to verify improvements in VF following exercise training should be employed after a minimum of 48 hours following physical activity

Antenna noise temperatures of the 34-meter beam-waveguide antenna with horns of different gains installed at F1

This article presents a set of theoretical and measured zenith-antenna noise temperatures at 8.45 GHz for the DSS-13 34-m beam-waveguide antenna when horns of different gains are installed at F1. The methodology for calculations is shown in detail. The major differences between calculated and measured values are attributed to changes in subreflector support leg scattering when illuminated by the various horns

The Effects of a High Fat Meal on Blood Flow Regulation during Arm Exercise

A diet high in saturated fats results in endothelial dysfunction and can lead to atherosclerosis, a precursor to cardiovascular disease. Exercise training is a potent stimulus though to mitigate the negative effects of a high saturated fat diet; however, it is unclear how high-saturated fat meal (HSFM) consumption impacts blood flow regulation during a single exercise session. PURPOSE: This study sought to examine the impact of a single HSFM on peripheral vascular function during an acute upper limb exercise bout. METHODS: Ten young healthy individuals completed two sessions of progressive handgrip exercise. Subjects either consumed a HSFM (0.84 g of fat/kg of body weight) 4 hours prior or remained fasted before the exercise bout. Progressive rhythmic handgrip exercise (6kg, 12kg, 18kg) was performed for 3 minutes per stage at rate of 1 Hz. The brachial artery (BA) diameter and blood velocity was obtained using Doppler Ultrasound (GE Logiq e) and BA blood flow was calculated with these values. RESULTS: BA blood flow and flow mediated dilation (normalized for shear rate) during the handgrip exercise significant increased from baseline in all workloads, but no differences were revealed in response to the HSFM consumption. CONCLUSION: Progressive handgrip exercise augmented BA blood flow and flow mediated dilation in both testing days; however, there was no significant differences following the HSFM consumption. This suggests that upper limb blood flow regulation during exercise is unaltered by a high fat meal in young healthy individuals.https://scholarscompass.vcu.edu/gradposters/1060/thumbnail.jp

Near-infrared Hong-Ou-Mandel interference on a silicon quantum photonic circuit

Near-infrared Hong-Ou-Mandel quantum interference is observed in silicon nanophotonic directional couplers with raw visibilities on-chip at 90.5%. Spectrally-bright 1557-nm two-photon states are generated in a periodically-poled KTiOPO4 waveguide chip, serving as the entangled photon source and pumped with a self-injection locked laser, for the photon statistical measurements. Efficient four-port coupling in the communications C-band and in the high-index-contrast silicon photonics platform is demonstrated, with matching theoretical predictions of the quantum interference visibility. Constituents for the residual quantum visibility imperfection are examined, supported with theoretical analysis of the sequentially-triggered multipair biphoton contribution and techniques for visibility compensation, towards scalable high-bitrate quantum information processing and communications.Comment: 15 pages, 6 figure

Anomalous Exponent of the Spin Correlation Function of a Quantum Hall Edge

The charge and spin correlation functions of partially spin-polarized edge electrons of a quantum Hall bar are studied using effective Hamiltonian and bosonization techniques. In the presence of the Coulomb interaction between the edges with opposite chirality we find a different crossover behavior in spin and charge correlation functions. The crossover of the spin correlation function in the Coulomb dominated regime is characterized by an anomalous exponent, which originates from the finite value of the effective interaction for the spin degree of freedom in the long wavelength limit. The anomalous exponent may be determined by measuring nuclear spin relaxation rates in a narrow quantum Hall bar or in a quantum wire in strong magnetic fields.Comment: 4 pages, Revtex file, no figures. To appear in Physical Revews B, Rapid communication

Abelian subgroups of Garside groups

In this paper, we show that for every abelian subgroup $H$ of a Garside group, some conjugate $g^{-1}Hg$ consists of ultra summit elements and the centralizer of $H$ is a finite index subgroup of the normalizer of $H$. Combining with the results on translation numbers in Garside groups, we obtain an easy proof of the algebraic flat torus theorem for Garside groups and solve several algorithmic problems concerning abelian subgroups of Garside groups.Comment: This article replaces our earlier preprint "Stable super summit sets in Garside groups", arXiv:math.GT/060258

Wigner Crystal State for the Edge Electrons in the Quantum Hall Effect at Filling ν=2\nu = 2

The electronic excitations at the edges of a Hall bar not much wider than a few magnetic lengths are studied theoretically at filling $\nu = 2$. Both mean-field theory and Luttinger liquid theory techniques are employed for the case of a null Zeeman energy splitting. The first calculation yields a stable spin-density wave state along the bar, while the second one predicts dominant Wigner-crystal correlations along the edges of the bar. We propose an antiferromagnetic Wigner-crystal groundstate for the edge electrons that reconciles the two results. A net Zeeman splitting is found to produce canting of the antiferromagnetic order.Comment: 22 pgs. of PLAIN TeX, 1 fig. in postscript, published versio

FAP-overexpressing fibroblasts produce an extracellular matrix that enhances invasive velocity and directionality of pancreatic cancer cells

<p>Abstract</p> <p>Background</p> <p>Alterations towards a permissive stromal microenvironment provide important cues for tumor growth, invasion, and metastasis. In this study, Fibroblast activation protein (FAP), a serine protease selectively produced by tumor-associated fibroblasts in over 90% of epithelial tumors, was used as a platform for studying tumor-stromal interactions.</p> <p>We tested the hypothesis that FAP enzymatic activity locally modifies stromal ECM (extracellular matrix) components thus facilitating the formation of a permissive microenvironment promoting tumor invasion in human pancreatic cancer.</p> <p>Methods</p> <p>We generated a tetracycline-inducible FAP overexpressing fibroblastic cell line to synthesize an <it>in vivo</it>-like 3-dimensional (3D) matrix system which was utilized as a stromal landscape for studying matrix-induced cancer cell behaviors. A FAP-dependent topographical and compositional alteration of the ECM was characterized by measuring the relative orientation angles of fibronectin fibers and by Western blot analyses. The role of FAP in the matrix-induced permissive tumor behavior was assessed in Panc-1 cells in assorted matrices by time-lapse acquisition assays. Also, FAP⁺matrix-induced regulatory molecules in cancer cells were determined by Western blot analyses.</p> <p>Results</p> <p>We observed that FAP remodels the ECM through modulating protein levels, as well as through increasing levels of fibronectin and collagen fiber organization. FAP-dependent architectural/compositional alterations of the ECM promote tumor invasion along characteristic parallel fiber orientations, as demonstrated by enhanced directionality and velocity of pancreatic cancer cells on FAP⁺matrices. This phenotype can be reversed by inhibition of FAP enzymatic activity during matrix production resulting in the disorganization of the ECM and impeded tumor invasion. We also report that the FAP⁺ matrix-induced tumor invasion phenotype is β₁-integrin/FAK mediated.</p> <p>Conclusion</p> <p>Cancer cell invasiveness can be affected by alterations in the tumor microenvironment. Disruption of FAP activity and β₁-integrins may abrogate the invasive capabilities of pancreatic and other tumors by disrupting the FAP-directed organization of stromal ECM and blocking β₁-integrin dependent cell-matrix interactions. This provides a novel preclinical rationale for therapeutics aimed at interfering with the architectural organization of tumor-associated ECM. Better understanding of the stromal influences that fuel progressive tumorigenic behaviors may allow the effective future use of targeted therapeutics aimed at disrupting specific tumor-stromal interactions.</p

Far infrared observations of pre-protostellar sources in Lynds 183

Using ISOPHOT maps at 100 and 200um and raster scans at 100, 120, 150 and 200um we have detected four unresolved far-infrared sources in the high latitude molecular cloud L183. Two of the sources are identified with 1.3mm continuum sources found by Ward-Thompson et al. and are located near the temperature minimum and the coincident column density maximum of dust distribution. For these two sources, the ISO observations have enabled us to derive temperatures (about 8.3 K) and masses (about 1.4 and 2.4 solar masses). They are found to have masses greater than or comparable to their virial masses and are thus expected to undergo gravitational collapse. We classify them as pre-protostellar sources. The two new sources are good candidates for pre-protostellar sources or protostars within L183.Comment: 12 pages, 7 Postscript figures, 1 JPEG figure. Accepted for publication in Astronomy & Astrophysic