Dynamics of Bacterioplankton Abundance and Production in Seagrass Communities of a Hypersaline Lagoon

The significance of bacterioplankton in the flow of carbon and energy and in trophic dynamics of the upper Laguna Madre, Texas (USA), was estimated by measuring bacterioplankton abundance and production over an 18 mo period and over several diel cycles. Bacterioplankton production was estimated from incorporation rates of thymidine (DNA synthesis) and leucine (protein synthesis). These independent inhces of bacterial growth were generally in agreement and yielded nearly identical annual estimates of bacterial production (25.24 g C m-2 yr-1 based on thymidine and 25.12 g C m-2 yr-1based on leucine). Assuming a 30 % growth efficiency, the annual bacterioplankton growth could be supported by 15 % of the total primary production (seagrasses and phytoplankton), 17% of the above-ground production of the dominant seagrass, Halodule wrightii, or 103 % of the phytoplankton production. Bactenal abundance was high throughout the year, often exceeding 1 X 1010 cells 1-1. Bacterioplankton production varied seasonally and over the diel cycle, with maximal values during warmer months and dunng daytime. Although changes in water temperature could account for some of this variation, shifts in the quantity and quality of the organic substrates supporting bacterial growth appeared to be the major factors regulating the variations in bacterioplankton production. Bacterioplankton in the Laguna Madre are a large and rapidly growing source of biomass potentially available for higher trophic levels. If this biomass is efficiently used by grazers, bacteria may be a major \u27link\u27 between seagrass production and secondary producers in the Laguna Madre ecosystem

Enhanced Bacterioplankton Production and Respiration at Intermediate Salinities in the Mississippi River Plume

Bacterial abundance and production (thymidine and leucine incorporation) were measured along a salinity gradient from the Mississippi River (0 %0) to the open waters of the Gulf of Mexico (36 %0) during July-August 1990 and February 1991. Bacterial production in surface waters was maximal at intermediate salinities (15 to 30 %0). Nutrient enrichment experiments suggested that bacterial growth near the outflow of the river was C limited whereas bacteria in plume waters of intermediate salinities were P and N limited. Rates of plankton community oxygen demand measured during winter were also maximal at intermediate salinities indicating an area of increased heterotrophic activity. The oxygen demand associated with heterotrophic bacterioplankton activity during summer was an important factor leading to hypoxic conditions in bottom waters of the Louisiana continental shelf. In summer, bacterial abundance and production ranged from 0.25 to 3.34 X log cells 1-1 and from 4 to 90 µg C-1 d-1, respectively. In winter, the corresponding ranges were 0.36 to 1.09 X log cells 1‑-1 and 3 to 20 µg C-1 d-1\u27 Depth-integrated bacterial production on the Louisiana shelf decreased from 443 k 44 mg C m-2 d-1 in summer to 226 ± 124 mg C m-2 d-1 in winter. Using empirically-derived bacterial growth efficiency values of 19 and 29 %, we estimated that bacterial production in summer could be supported by 10 to 58 % of phytoplankton production. In winter, the amount of carbon needed to support bacterial production exceeded phytoplankton production suggesting that bacterial growth during this season was heavily dependent on riverine sources of organic matter

Comparisons of Characteristics of Magnetic Clouds and Cloud-Like Structures During 1995-2012

Using eighteen years (1995 - 2012) of solar wind plasma and magnetic field data (observed by the Wind spacecraft), solar activity (e.g. sunspot number: SSN), and the geomagnetic activity index (Dst), we have identified 168 magnetic clouds (MCs) and 197 magnetic cloud - like structures (MCLs), and we have made relevant comparisons. The following features are found during seven different periods (TP: Total period during 1995 - 2012, P1 and P2: first and second half period during 1995 - 2003 and 2004 - 2012, Q1 and Q2: quiet periods during 1995 - 1997 and 2007 - 2009, A1 and A2: active periods during 1998 - 2006 and 2010 - 2012). (1) During the total period the yearly occurrence frequency is 9.3 for MCs and 10.9 for MCLs. (2) In the quiet periods Q1 > Q1 and Q2 > Q2, but in the active periods A1 A1 and A2 A2. (3) The minimum Bz (Bzmin) inside of a MC is well correlated with the intensity of geomagnetic activity, Dstmin (minimum Dst found within a storm event) for MCs (with a Pearson correlation coefficient, c.c. = 0.75, and the fitting function is Dstmin = 0.90+7.78Bzmin), but Bzmin for MCLs is not well correlated with the Dst index (c.c. = 0.56, and the fitting function is Dstmin = -9.40+ 4.58 Bzmin). (4) MCs play a major role in producing geomagnetic storms: the absolute value of the average Dstmin (MC = -70 nT) for MCs associated geomagnetic storms is two times stronger than that for MCLs (MCL = -35 nT), due to the difference in the IMF (interplanetary magnetic field) strength. (5) The SSN is not correlated with MCs (TP, c.c. = 0.27), but is well associated with MCLs (TP, c.c. = 0.85). Note that the c.c. for SSN vs. P2 is higher than that for SSN vs. P2. (6) Averages of IMF, solar wind speed, and density inside of the MCs are higher than those inside of the MCLs. (7) The average of MC duration (approx. = 18.82 hours) is approx. = 20 % longer than the average of MCL duration (approx. = 15.69 hours). (8) There are more MCs than MCLs in the quiet solar period, and more MCLs than MCs in the active solar period, probably due to the interaction between a MC and another significant interplanetary disturbance (including another MC) which could obviously change the character of a MC, but we speculate that some MCLs are no doubt due to other factors such as complex birth conditions at the Sun

Hydrodynamical Simulations of the Barred Spiral Galaxy NGC 1097

NGC 1097 is a nearby barred spiral galaxy believed to be interacting with the elliptical galaxy NGC 1097A located to its northwest. It hosts a Seyfert 1 nucleus surrounded by a circumnuclear starburst ring. Two straight dust lanes connected to the ring extend almost continuously out to the bar. The other ends of the dust lanes attach to two main spiral arms. To provide a physical understanding of its structural and kinematical properties, two-dimensional hydrodynamical simulations have been carried out. Numerical calculations reveal that many features of the gas morphology and kinematics can be reproduced provided that the gas flow is governed by a gravitational potential associated with a slowly rotating strong bar. By including the self-gravity of the gas disk in our calculation, we have found the starburst ring to be gravitationally unstable which is consistent with the observation in \citet{hsieh11}. Our simulations show that the gas inflow rate is 0.17 M_\sun yr$^{-1}$ into the region within the starburst ring even after its formation, leading to the coexistence of both a nuclear ring and a circumnuclear disk.Comment: 32 pages, 14 figures, 1 table, accepted for publication in the Ap

A Quantum Scattering Interferometer

The collision of two ultra-cold atoms results in a quantum-mechanical superposition of two outcomes: each atom continues without scattering and each atom scatters as a spherically outgoing wave with an s-wave phase shift. The magnitude of the s-wave phase shift depends very sensitively on the interaction between the atoms. Quantum scattering and the underlying phase shifts are vitally important in many areas of contemporary atomic physics, including Bose-Einstein condensates, degenerate Fermi gases, frequency shifts in atomic clocks, and magnetically-tuned Feshbach resonances. Precise measurements of quantum scattering phase shifts have not been possible until now because, in scattering experiments, the number of scattered atoms depends on the s-wave phase shifts as well as the atomic density, which cannot be measured precisely. Here we demonstrate a fundamentally new type of scattering experiment that interferometrically detects the quantum scattering phase shifts of individual atoms. By performing an atomic clock measurement using only the scattered part of each atom, we directly and precisely measure the difference of the s-wave phase shifts for the two clock states in a density independent manner. Our method will give the most direct and precise measurements of ultracold atom-atom interactions and will place stringent limits on the time variations of fundamental constants.Comment: Corrected formatting and typo

Irradiated Human Endothelial Progenitor Cells Induce Bystander Killing in Human Non-Small Cell Lung and Pancreatic Cancer Cells

Purpose To investigate whether irradiated human endothelial progenitor cells (hEPCs) could induce bystander killing in the A549 non-small cell lung cancer (NSCLC) cells and help explain the improved radiation-induced tumor cures observed in A549 tumor xenografts co-injected with hEPCs. Materials and Methods We investigated whether co-injection of CBM3 hEPCs with A549 NSCLC cells would alter tumor xenograft growth rate or tumor cure after a single dose of 0 or 5 Gy of X-rays. We then utilized dual chamber Transwell dishes, to test whether medium from irradiated CBM3 and CBM4 hEPCs would induce bystander cell killing in A549 cells, and as an additional control, in human pancreatic cancer MIA PaCa-2 cells. The CBM3 and CBM4 hEPCs were plated into the upper Transwell chamber and the A549 or MIA PaCa-2 cells were plated in the lower Transwell chamber. The top inserts with the CBM3 or CBM4 hEPCs cells were subsequently removed, irradiated, and then placed back into the Transwell dish for 3 h to allow for diffusion of any potential bystander factors from the irradiated hEPCs in the upper chamber through the permeable membrane to the unirradiated cancer cells in the lower chamber. After the 3 h incubation, the cancer cells were re-plated for clonogenic survival. Results We found that co-injection of CBM3 hEPCs with A549 NSCLC cells significantly increased the tumor growth rate compared to A549 cells alone, but paradoxically also increased A549 tumor cure after a single dose of 5 Gy of X-rays (P < 0.05). We hypothesized that irradiated hEPCs may be inducing bystander killing in the A549 NSCLC cells in tumor xenografts, thus improving tumor cure. Bystander studies clearly showed that exposure to the medium from irradiated CBM3 and CBM4 hEPCs induced significant bystander killing and decreased the surviving fraction of A549 and MIA PaCa-2 cells to 0.46 (46%) ± 0.22 and 0.74 ± 0.07 (74%) respectively (P < 0.005, P < 0.0001). In addition, antibody depletion studies demonstrated that the bystander killing induced in both A549 and MIA PaCa-2 cells was mediated by the cytokines TNF-α and TGF-β (P < 0.05). Conclusions These data provide evidence that irradiated hEPCs can induce strong bystander killing in A549 and MIA PaCa-2 human cancer cells and that this bystander killing is mediated by the cytokines TNF-α and TGF-β

Hyperspectral Imaging for Burn Depth Assessment in an Animal Model

Differentiating between superficial and deep-dermal (DD) burns remains challenging. Superficial-dermal burns heal with conservative treatment; DD burns often require excision and skin grafting. Decision of surgical treatment is often delayed until burn depth is definitively identified. This study\u27s aim is to assess the ability of hyperspectral imaging (HSI) to differentiate burn depth. METHODS: Thermal injury of graded severity was generated on the dorsum of hairless mice with a heated brass rod. Perfusion and oxygenation parameters of injured skin were measured with HSI, a noninvasive method of diffuse reflectance spectroscopy, at 2 minutes, 1, 24, 48 and 72 hours after wounding. Burn depth was measured histologically in 12 mice from each burn group (n = 72) at 72 hours. RESULTS: Three levels of burn depth were verified histologically: intermediate-dermal (ID), DD, and full-thickness. At 24 hours post injury, total hemoglobin (tHb) increased by 67% and 16% in ID and DD burns, respectively. In contrast, tHb decreased to 36% of its original levels in full-thickness burns. Differences in deoxygenated and tHb among all groups were significant (P \u3c 0.001) at 24 hours post injury. CONCLUSIONS: HSI was able to differentiate among 3 discrete levels of burn injury. This is likely because of its correlation with skin perfusion: superficial burn injury causes an inflammatory response and increased perfusion to the burn site, whereas deeper burns destroy the dermal microvasculature and a decrease in perfusion follows. This study supports further investigation of HSI in early burn depth assessment

Exploring The Efficacy of Digital Meme Marketing Campaigns in Generating Leads Within the Generation Z Demographic

Quite recently, marketers have used memes because they entice customers’ attention. It serves as a means to have a dialogue between customers and companies. Some companies would even hire people to browse the internet for relevant memes. The emergence of Generation Z, who are digital natives, has brought significant changes to how businesses interact with their target audience. One potential strategy is to use digital memes as a marketing tool to engage them. The study, using 271 respondents, investigates the use of the aforementioned tool to determine its appropriateness in lead generation based on the Attention, Interest, Desire, Action (AIDA) model. Using the software Analysis of Moment Structures (AMOS), a descriptive exploratory design using Structural Equation Modeling (SEM) was used to investigate the relationship between the different variables in the study. The findings show that attention impacts interest, interest influences desire, and desire significantly affects action at a significance level of p < 0.01. The study revealed that Digital memes are an effective tool that can be utilized to generate leads. Businesses can use digital memes to engage with the Generation Z segment. However, prudence in creating memes must align the message with corporate values and be relevant to the target audience