Microbial size spectra from diverse marine ecosystems

Submitted in partial fulfillment of the requirements for the degree of Doctor of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 1996Characteristics of microbial size spectra (bacteria and phytoplankton) were examined in relation to changes in ecosystem productivity and environmental perturbations. Samples were obtained from productive coastal waters in Massachusetts and Cape Cod Bays, oligotrophic waters in the Sargasso Sea and high nutrient, low chlorophyll waters in the equatorial Pacific. In general, a relative predominance of larger bacteria and phytoplankton cells was observed in early spring, where low temperatures resulted in wellmixed waters and high nutrient concentrations. Seasonal succession was accompanied by a shift in the size spectrum to smaller cells, coinciding with rising temperatures, stratification of the water column and diminishing nutrient concentrations. In stratified waters, larger mean bacteria and phytoplankton sizes were observed in surface and deep waters, whereas smaller sizes were observed around the chlorophyll maximum. Bacteria and phytoplankton growth were well correlated with mean bacteria sizes varying positively with mean phytoplankton sizes. Data pooled from all locations showed that the size spectral characteristics most sensitive to environmental change were the mean cell size, bacteria intercept and phytoplankton slope of the normalized concentration size spectrum. Increases in ecosystem productivity, chlorophyll, particulates and nutrients were generally accompanied by shifts in the size spectra to larger bacteria and phytoplankton.The work was partially funded by the National Science Foundation (JGOFS) OCE- 9022285, OCE-9302529, OCE-9012117; NOAA Sea Grant (MIT); the Massachusetts Water Authority contract #S179; and fellowship funding from the National University of Singapore Overseas Scholarship

Insulin Therapy and Body Weight, Body Composition and Muscular Strength in Patients with Type 2 Diabetes Mellitus

Aims. To determine the progression of body weight (BW) and body composition (BC) in patients with type 2 diabetes mellitus (T2D) on insulin therapy and the consequences on muscle strength (MS) as a reflect of free fat mass increases. Research design and methods. We analysed BC using air displacement plethysmography and MS by hand grip dynamometry in 40 T2D before and after three (M3) and six months (M6) of insulin therapy. Results. at baseline HbA1c was 9.76 ±1.6% and BW was stable with fat mass (FM) 28 ± 10.7 kg; and fat free mass (FFM) 52.4 ± 11 kg; at M6, HbA1c improved to 7.56 ± 0.8%; insulin doses tended to increase. BW gain at M6 was + 3.2 ± 4.2 kg and with an increase of only 25% by M3; it was composed of FM, whereas FFM was unchanged. MS did not increase on insulin therapy. Conclusions. In T2D, BW gain was composed exclusively of FM with no improvement in MS

Photon Counting Using Edge-Detection Algorithm

New applications such as high-datarate, photon-starved, free-space optical communications require photon counting at flux rates into gigaphoton-per-second regimes coupled with subnanosecond timing accuracy. Current single-photon detectors that are capable of handling such operating conditions are designed in an array format and produce output pulses that span multiple sample times. In order to discern one pulse from another and not to overcount the number of incoming photons, a detection algorithm must be applied to the sampled detector output pulses. As flux rates increase, the ability to implement such a detection algorithm becomes difficult within a digital processor that may reside within a field-programmable gate array (FPGA). Systems have been developed and implemented to both characterize gigahertz bandwidth single-photon detectors, as well as process photon count signals at rates into gigaphotons per second in order to implement communications links at SCPPM (serial concatenated pulse position modulation) encoded data rates exceeding 100 megabits per second with efficiencies greater than two bits per detected photon. A hardware edge-detection algorithm and corresponding signal combining and deserialization hardware were developed to meet these requirements at sample rates up to 10 GHz. The photon discriminator deserializer hardware board accepts four inputs, which allows for the ability to take inputs from a quadphoton counting detector, to support requirements for optical tracking with a reduced number of hardware components. The four inputs are hardware leading-edge detected independently. After leading-edge detection, the resultant samples are ORed together prior to deserialization. The deserialization is performed to reduce the rate at which data is passed to a digital signal processor, perhaps residing within an FPGA. The hardware implements four separate analog inputs that are connected through RF connectors. Each analog input is fed to a high-speed 1-bit comparator, which digitizes the input referenced to an adjustable threshold value. This results in four independent serial sample streams of binary 1s and 0s, which are ORed together at rates up to 10 GHz. This single serial stream is then deserialized by a factor of 16 to create 16 signal lines at a rate of 622.5 MHz or lower for input to a high-speed digital processor assembly. The new design and corresponding hardware can be employed with a quad-photon counting detector capable of handling photon rates on the order of multi-gigaphotons per second, whereas prior art was only capable of handling a single input at 1/4 the flux rate. Additionally, the hardware edge-detection algorithm has provided the ability to process 3-10 higher photon flux rates than previously possible by removing the limitation that photoncounting detector output pulses on multiple channels being ORed not overlap. Now, only the leading edges of the pulses are required to not overlap. This new photon counting digitizer hardware architecture supports a universal front end for an optical communications receiver operating at data rates from kilobits to over one gigabit per second to meet increased mission data volume requirements

Intermediate Wakimoto modules for Affine sl(n+1)

We construct certain boson type realizations of affine sl(n+1) that depend on a parameter r. When r=0 we get a Fock space realization of Imaginary Verma modules appearing in the work of the first author and when r=n they are the Wakimoto modules described in the work of Feigin and Frenkel

“MUMI DANSA” (Merchandise Unik, Menarik dan Edukatif dengan Desain Peta)

MUMI DANSA is one of the many alternatives of creative art that is able to give educative introduction about the culture of Nusantara. The goal of the project and the products is to have innovative point of view that could be given out into products design, the aim is also to provide fields of jobs, and educative points of view that could give knowledge and introduction about uniqueness of Nusantara. The project is done with 4 methods, which are promotion and publication, marketing, production, and methods for research and design development. The MUMI DANSA products which are t-shirts and accessories

Microbal size spectra from diverse marine ecosystems

Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1996.Includes bibliographical references.by Karina Y.H. Gin.Sc.D