Interaction between Angiotensin II and BDNF in Modulating Sympathetic Nerve Activity

Over activation of the sympathetic nervous system is prevalent in many forms of cardiovascular disease such as chronic heart failure (CHF) and hypertension. Although increased neuronal renin-angiotensin system activity in presympathetic neurons has been well implicated in mediating this sympatho-excitation, many of the neuronal effects of angiotensin II (Ang II) signaling remain poorly understood. One particular mechanism of Ang II-mediated increases in presympathetic neuronal activity is through reductions in voltage-gated K+ currents. Another pathway that has profound effects on neuronal K+ currents and that has been previously implicated in Ang II-signaling is brain-derived neurotrophic factor (BDNF) activity through its receptor tyrosine kinase B (TrkB). Therefore, we hypothesized that BDNF/TrkB signaling is an important mediator of the neuronal effects of Ang II in modulating voltage-gated K+ currents and autonomic dysfunction in cardiovascular disease states such as CHF and hypertension. We employed cell culture and whole-animal models to explore this hypothesis and utilized electrophysiological, molecular, and in vivo physiological techniques. Patch-clamp studies demonstrated that BDNF is involved in Ang II-induced reductions to K+ currents. Further in-vivo experiments found that overexpression of Kv4.3 into the rostral ventrolateral medulla attenuates the increase in sympathetic nerve activity of rats post-myocardial infarction. Baroreflex dysfunction is common in CHF, and desensitization of central neuronal areas such as the nucleus tractus solitarius (NTS) can mediate this dysfunction. We therefore hypothesized that changes in BDNF/TrkB signaling in the NTS mediated baroreflex dysfunction in CHF. Blocking TrkB with ANA-12 in the NTS blunted baroreflex sensitivity in sham rats but had little effect on the already blunted baroreflex sensitivity of CHF rats. TrkB expression was reduced in CHF rats, implicating reduced BDNF/TrkB signaling in the NTS as a mechanism for reduced baroreflex sensitivity during CHF. In a final set of experiments we explored the connection between Ang II and BDNF in vivo. Central administration of Ang II increased mean arterial pressure and induced sympatho-excitation, both of which were attenuated by coinfusion of ANA-12. Overall, these data implicate BDNF as an important factor in mediating the neuronal effects of Ang II on K+ currents, hemodynamics, baroreflex sensitivity, and sympathetic nerve activity

Energy Consumption and Product Throughput of Glass-Doored and Open Refrigerated Display Cases in Supermarkets [abstract]

Only abstract of poster available.Track III: Energy InfrastructureRefrigerated display cases are utilized by supermarkets to store and display food products in a manner that extends food shelf life and ensures food safety. Supermarkets operate their refrigeration systems continuously to maintain proper food storage conditions. Continual operation of this refrigeration equipment on a nationwide scale accounts for approximately 0.33 quads/yr of electrical energy. Infiltration accounts for over 70% of the refrigeration load in open refrigerated display cases. Clearly, an increase in the energy efficiency of refrigerated display cases will result in significantly reduced energy consumption and cost. Thus, the objective of this project is to compare a typical open refrigerated display case to a typical glass-doored refrigerated display case with the aim of quantifying the following: • The difference in overall energy consumption between the cases. • The normalized difference in food product sales between the cases. Two supermarkets are being used as test sites, which are similarly situated to ensure that climate, weather, time-of-year and economic conditions of the shoppers are comparable. One supermarket will receive an open refrigerated display case and the other will receive a doored refrigerated display case. Each refrigerated display case will be a medium temperature, self-service prepackaged deli or beverage case between 8 and 25 nominal linear feet. The thermal performance and product sales of each refrigerated display case will be monitored. Automated data logging systems will be used to measure quantities such as refrigeration load, voltage, current, temperature, humidity and pressure. Product sales for each refrigerated display case and total store product sales will be tracked using Stock Keeping Units (SKUs) and the supermarkets' computerized Point of Sale (POS) system. The resulting data will be analyzed to determine the difference in energy consumption and product sales between the two refrigerated cases

High Efficiency Evaporator Fan Motors for Commercial Refrigeration Applications

Evaporator fan motors used in commercial refrigeration applications are fractional horsepower in size, are responsible for moving air across the evaporator coil, and typically run at one speed. Historically, shaded-pole motors have been the most commonly used evaporator fan motors in commercial refrigeration equipment and beverage vending machines. These motors, a type of single-phase AC induction motor, are the simplest and least expensive type of fractional-horsepower motor. They are also the least efficient, with the common 9–12 W sizes exhibiting an efficiency of approximately 20%. Electronically commutated (EC) motors, also known as brushless DC motors, became widely commercialized in the late 1980s, and their use in commercial refrigeration applications has increased within the last 10 to 15 years because of economic incentives and regulatory requirements. Another motor type, the permanent split capacitor (PSC) motor, offers a mid-point between shaded-pole and EC motor price and efficiency levels. Typically for commercial refrigeration evaporator fan motor applications, EC motors are 66% efficient and PSC motors are usually about 29% efficient.  A new motor technology, a type of permanent magnet synchronous AC motor that can directly use grid-supplied AC current without the need to rectify to DC, has recently been commercialized. This new motor has the potential to significantly reduce the energy consumption of evaporator fans in commercial refrigeration equipment. Previously, synchronous motors have been prohibitively expensive for evaporator fan applications because of the high cost of the electronic control circuit that is required to bring the synchronous motor up to synchronous speed. However, this new motor technology makes use of a novel patent-pending controller that is simpler and lower in cost than previous synchronous motor controllers or EC motor controllers, making the new motor a cost-effective alternative in the commercial refrigeration market.  In this paper, the results of field demonstrations, consisting of side-by-side measurements of the power consumption of the new motor technology versus shaded-pole, PSC, or EC evaporator fan motors in identical refrigerated display cases, are presented. Measured quantities include fan motor power, current, and power factor, as well as display case discharge and return air temperatures and ambient store temperature. Currently, field demonstrations are being conducted at six supermarkets and commissaries located in Kansas City, MO, San Antonio, TX and San Diego, CA, with the duration of these tests ranging from approximately one month to over six months. Initial results from the field demonstrations indicate that the new synchronous AC motor technology is approximately 20 to 30% more energy efficient than existing EC motors and nearly 80% more energy efficient than shaded-pole motors. In addition, the new motor exhibits a power factor of approximately 0.86, which is on average 40% greater than that of existing evaporator fan motors. Analyses indicate that retrofitting the installed base of commercial refrigeration evaporator fan motors with the new motors would produce a 68% evaporator fan site energy savings, or 4.9×109 kWh/year for the installed base of commercial refrigeration evaporator fan motors. This would result in an annual cost savings of $516 million and reduce the annual CO2 equivalent emissions by 8.1×109 lb

Survey of Porcine Reproductive and Respiratory Syndrome

A swine disease of unknown etiology was described in 1987 by veterinarians and researchers in the United States. Since no known pathogens could be implicated, it was believed to be unique. This decision was based on the disease\u27s severity and duration as well as a combination of reproductive and respiratory signs. Within three years of its discovery, clinical signs of the mystery swine disease were reported in all principal areas of swine production in the United States. Months later, a syndrome similar to the U.S. mysterious disease was reported from across the Atlantic Ocean - Germany

The Temperature-Density Relation in the Intergalactic Medium at Redshift <z>=2.4

We present new measurements of the temperature-density (T-rho) relation for neutral hydrogen in the 2.0 < z < 2.8 intergalactic medium (IGM) using a sample of ~6000 individual HI absorbers fitted with Voigt profiles constrained in all cases by multiple Lyman series transitions. We find model independent evidence for a positive correlation between the column density of HI (NHI) and the minimum observed velocity width of absorbers (bmin). With minimal interpretation, this implies that the temperature-density relation in the IGM is not "inverted", contrary to many recent studies. Fitting bmin as a function of NHI results in line width - column density dependence of the form bdmin = b_0 [NHI/N_(HI,0)]^(Gamma-1) with a minimum line width at mean density rhobar [N_(HI, 0) = 10^13.6 cm^-2] of b_0 = 17.9 +- 0.2 km/s and a power-law index of (Gamma-1) = 0.15 +- 0.02. Using analytic arguments, these measurements imply an "equation of state" for the IGM at = 2.4 of the form T = T_0 (rho/rhobar)^(gamma-1) with a temperature at mean density of T_0 = (1.94 +- 0.05) x 10^4 K and a power-law index (gamma -1) = 0.46 +- 0.05.Comment: 6 pages, 2 figure, accepted for publication in ApJ

Resolving the high redshift Lyman-alpha forest in smoothed particle hydrodynamics simulations

We use a large set of cosmological smoothed particle hydrodynamics (SPH) simulations to examine the effect of mass resolution and box size on synthetic Lya forest spectra at 2 \leq z \leq 5. The mass resolution requirements for the convergence of the mean Lya flux and flux power spectrum at z=5 are significantly stricter than at lower redshift. This is because transmission in the high redshift Lya forest is primarily due to underdense regions in the intergalactic medium (IGM), and these are less well resolved compared to the moderately overdense regions which dominate the Lya forest opacity at z~2-3. We further find that the gas density distribution in our simulations differs significantly from previous results in the literature at large overdensities (\Delta>10). We conclude that studies of the Lya forest at z=5 using SPH simulations require a gas particle mass of M_gas \leq 2x10^5 M_sol/h, which is >8 times the value required at z=2. A box size of at least 40 Mpc/h is preferable at all redshifts.Comment: 5 pages, 5 figures, 2 tables, accepted by MNRA

The Luminosity Function of Young Star Clusters In "The Antennae" Galaxies (NGC 4038/4039)

The WFPC2 of the HST has been used to obtain high-resolution images of NGC 4038/4039 that go roughly 3 magnitudes deeper in V than previous observations made during Cycle 2 (-14 < M_V < -6). To first order the luminosity function (LF) is a power law, with exponent \alpha = -2.12 +/- 0.04. However, after decoupling the cluster and stellar LFs, which overlap in the range -9 < M_V < -6, we find an apparent bend in the young cluster LF at approximately M_V = -10.4. The LF has a power law exponent -2.6 +/- 0.2 in the brightward and -1.7 +/- 0.2 in the faintward. The bend corresponds to a mass ~ 10^5 M_{\odot}, only slightly lower than the characteristic mass of globular clusters in the Milky Way (~2x10^5 M_{\odot}). The star clusters of the Antennae appear slightly resolved, with median effective radii of 4 +/- 1 pc, similar to or perhaps slightly larger than those of globular clusters in our Galaxy. However, the radial extents of some of the very young clusters (ages < 10 Myr) are much larger than those of old globular clusters. A combination of the UBVI colors, \Halpha morphology, and GHRS spectra enables us to age-date the clusters in different regions of The Antennae. We find two groups of young star clusters with ages <~ 20Myr and ~100Myr, as well as an intermediate-age group (~500 Myr) and a handful of old globular clusters from the progenitor galaxies. Age estimates derived from GHRS spectroscopy yield 3 +/- 1 Myr for Knot K (just south of the nucleus of NGC 4038) and 7 +/- 1 Myr for Knot S in the Western Loop, in good agreement with ages derived from the UBVI colors. Effective gas-outflow velocities from Knots S and K are estimated to be about 25-30 km/s. However, the measured widths of the interstellar absorption lines suggest dispersion velocities of ~400 km/s along the lines of sight to Knots S and K.Comment: 56 pages, 4 tables and 23 figures, texts in AAS style, to be published in A