Primer selection impacts specific population abundances but not community dynamics in a monthly time-series 16S rRNA gene amplicon analysis of coastal marine bacterioplankton.

Primers targeting the 16S small subunit ribosomal RNA marker gene, used to characterize bacterial and archaeal communities, have recently been re-evaluated for marine planktonic habitats. To investigate whether primer selection affects the ecological interpretation of bacterioplankton populations and community dynamics, amplicon sequencing with four primer sets targeting several hypervariable regions of the 16S rRNA gene was conducted on both mock communities constructed from cloned 16S rRNA genes and a time-series of DNA samples from the temperate coastal Santa Barbara Channel. Ecological interpretations of community structure (delineation of depth and seasonality, correlations with environmental factors) were similar across primer sets, while population dynamics varied. We observed substantial differences in relative abundances of taxa known to be poorly resolved by some primer sets, such as Thaumarchaeota and SAR11, and unexpected taxa including Roseobacter clades. Though the magnitude of relative abundances of common OTUs differed between primer sets, the relative abundances of the OTUs were nonetheless strongly correlated. We do not endorse one primer set but rather enumerate strengths and weaknesses to facilitate selection appropriate to a system or experimental goal. While 16S rRNA gene primer bias suggests caution in assessing quantitative population dynamics, community dynamics appear robust across studies using different primers

The Effect of Airline Scheduling on Airport Delays

With the passage of the Deregulation Act of 1978 the government unknowingly hastened the arrival of the “Hub and Spoke” system of airline operations. The passage of this act along with the increasing use of smaller commuter planes has caused the airlines to over schedule many of the larger hub airports in the United States causing many delays in the nation’s air traffic control system. Of the large hub airports in the United States a convenience sample was taken to ensure the needed data was present. Schedule data for the time period of May 2004 – June 2004 was collected and analyzed to find the impact that airline scheduling had on airport delays. Throughout the research it became clear that all the airports studied were not affected equally by airline scheduling, and that a handful of these airports operations were moderately to severely affected by airline scheduling

FOMC communications and the predictability of near-term policy decisions

In February 1994, the FOMC began a new era in transparency, gradually building a communications apparatus that conveys information about the Committee’s decisions and expectations. Has the new apparatus improved the public’s ability to predict FOMC interest rate decisions? New research based on the prices of fed funds futures shows that over the past decade, it has, especially over horizons of two to three months.Federal Open Market Committee ; Federal funds rate

Numerical Analysis of a Model for the Growth of Microorganisms

A system of first-order differential equations that arises in a model for the growth of microorganisms in a chemostat with Monod kinetics is studied. A new, semi-implicit numerical scheme is proposed to approximate solutions to the system. It is shown that the scheme is uniquely solvable and unconditionally stable, and further properties of the scheme are analyzed. The convergence rate of the numerical solution to the true solution of the system is given, and it is shown convergence of the numerical solutions to the true solutions is uniform over any interval [0, T ] for T \u3e 0

Elevated pCO2 enhances bacterioplankton removal of organic carbon.

Factors that affect the removal of organic carbon by heterotrophic bacterioplankton can impact the rate and magnitude of organic carbon loss in the ocean through the conversion of a portion of consumed organic carbon to CO2. Through enhanced rates of consumption, surface bacterioplankton communities can also reduce the amount of dissolved organic carbon (DOC) available for export from the surface ocean. The present study investigated the direct effects of elevated pCO2 on bacterioplankton removal of several forms of DOC ranging from glucose to complex phytoplankton exudate and lysate, and naturally occurring DOC. Elevated pCO2 (1000-1500 ppm) enhanced both the rate and magnitude of organic carbon removal by bacterioplankton communities compared to low (pre-industrial and ambient) pCO2 (250 -~400 ppm). The increased removal was largely due to enhanced respiration, rather than enhanced production of bacterioplankton biomass. The results suggest that elevated pCO2 can increase DOC consumption and decrease bacterioplankton growth efficiency, ultimately decreasing the amount of DOC available for vertical export and increasing the production of CO2 in the surface ocean

Solar absorption chiller

In developing nations access to electricity is inconsistent at best, and food spoilage is a prevalent issue. The solar powered absorption chiller is a refrigeration system designed to provide refrigeration to these developing areas. This year, our team has worked to develop a system where the sun\u27s rays are collected as heat to power an absorption refrigerator. The goal of this project was to take an existing solar tracker system and use its collected heat to power a refrigerator. Our team designed and built heat exchangers to extract heat from the concentrated solar system; assembled components for a fluid circulation loop; and retrofitted an absorption chiller refrigerator to be powered by our heated fluid. Additionally, we redesigned an existing solar tracking system to improve function and decrease power consumption. By the end of this year we assembled the entire system and performed months of solar testing as well as proof-ofconcept testing that the refrigerator could receive necessary heat through a heated fluid. By the end of the school year, we concluded that the heated fluid would need to reach 150°C to begin the refrigeration cycle (with current heat exchanger design), which was 25° higher than our solar testing had achieved. With further improvements, the refrigerator could be designed to run with lower heat inputs and the tracker system could be designed to attain heat at higher temperatures. With these changes, a working refrigeration system could have dramatic impacts on farming communities in developing countries; reducing food spoilage, increasing family income, and preventing food-borne illnesses

Influence of coral and algal exudates on microbially mediated reef metabolism.

Benthic primary producers in tropical reef ecosystems can alter biogeochemical cycling and microbial processes in the surrounding seawater. In order to quantify these influences, we measured rates of photosynthesis, respiration, and dissolved organic carbon (DOC) exudate release by the dominant benthic primary producers (calcifying and non-calcifying macroalgae, turf-algae and corals) on reefs of Mo'orea French Polynesia. Subsequently, we examined planktonic and benthic microbial community response to these dissolved exudates by measuring bacterial growth rates and oxygen and DOC fluxes in dark and daylight incubation experiments. All benthic primary producers exuded significant quantities of DOC (roughly 10% of their daily fixed carbon) into the surrounding water over a diurnal cycle. The microbial community responses were dependent upon the source of the exudates and whether the inoculum of microbes included planktonic or planktonic plus benthic communities. The planktonic and benthic microbial communities in the unamended control treatments exhibited opposing influences on DO concentration where respiration dominated in treatments comprised solely of plankton and autotrophy dominated in treatments with benthic plus plankon microbial communities. Coral exudates (and associated inorganic nutrients) caused a shift towards a net autotrophic microbial metabolism by increasing the net production of oxygen by the benthic and decreasing the net consumption of oxygen by the planktonic microbial community. In contrast, the addition of algal exudates decreased the net primary production by the benthic communities and increased the net consumption of oxygen by the planktonic microbial community thereby resulting in a shift towards net heterotrophic community metabolism. When scaled up to the reef habitat, exudate-induced effects on microbial respiration did not outweigh the high oxygen production rates of benthic algae, such that reef areas dominated with benthic primary producers were always estimated to be net autotrophic. However, estimates of microbial consumption of DOC at the reef scale surpassed the DOC exudation rates suggesting net consumption of DOC at the reef-scale. In situ mesocosm experiments using custom-made benthic chambers placed over different types of benthic communities exhibited identical trends to those found in incubation experiments. Here we provide the first comprehensive dataset examining direct primary producer-induced, and indirect microbially mediated alterations of elemental cycling in both benthic and planktonic reef environments over diurnal cycles. Our results highlight the variability of the influence of different benthic primary producers on microbial metabolism in reef ecosystems and the potential implications for energy transfer to higher trophic levels during shifts from coral to algal dominance on reefs

Some Monte Carlo results on nonparametric changepoint tests

An examination of the small-sample properties of nonparametric changepoint tests using Monte Carlo analysis to investigate the probabilities of false-positive tests under alternative assumptions about the time-series properties of the underlying process. ; An analysis of whether depositor preference legislation reduced the FDIC's failed-bank resolution costs in 1984-92, and whether nondepositors' responses may have partially undone the intended benefits of such legislation.Inflation (Finance) ; Statistics ; Time-series analysis

Fuzzy logic load forecasting with genetic algorithm parameter adjustment

World-wide pressure on existing power distribution systems calls for action to be taken in order to curb the energy deficit. The concept of a smart grid can assist since a significant function is the improvement of energy efficiency in transmission and usage. This is also known as energy management. Load forecasting can indirectly aid energy management by raising user awareness to reduce the peak and total power usage. Load forecasting has been implemented using many different methods over the years, from statistical methods to computational intelligence methods. Combinations of methods also exist to enhance the forecasting capabilities. Following from observations made, it was hypothesised that a fuzzy logic load forecasting algorithm could be improved by incorporating an optimisation technique such as genetic algorithms. In order to observe the effects of a genetic algorithm on a fuzzy logic load forecasting system, MATLAB® was used to implement a load forecasting algorithm using fuzzy logic systems and genetic algorithms. The fuzzy logic systems used the day (week or weekend), the time of day and the historic power usage to perform the forecasting. The genetic algorithm adjusted the fuzzy logic parameters to minimise the peak and total energy errors in a 24 hour period. Using data from one week prior to the test yielded the most accurate results after considering varying quantities of input data. The results obtained from five case studies indicated a good correlation between the forecast and measured values. Initial results were obtained using a priori knowledge of the behaviour of the system, then the genetic algorithm was implemented. The full week forecast results showed an average improvement, for the five cases, of 4.32 and 18.95 times for the peak energy error and the total energy error respectively. This indicates that the dissertation hypothesis was proven to be correct

Purification and Characterization of Enzymes from Yeast: An Extended Undergraduate Laboratory Sequence for Large Classes

Providing a project-based experience in an undergraduate biochemistry laboratory class can be complex with large class sizes and limited resources. We have designed a 6-week curriculum during which students purify and characterize the enzymes invertase and phosphatase from bakers yeast. Purification is performed in two stages via ethanol precipitation and anion exchange chromatography, and students perform both direct and coupled enzyme assays. By completion of the experimental series, students are able to identify which enzymes they have purified and have obtained kinetic parameters for one. This experimental series requires minimal instructor preparation time, is cost effective, and works with multiple sections of large groups of students. Students participating in this sequence showed increases in conceptual understanding of biochemical concepts as measured through in-class assessments and anonymous surveys