MA estimation in polynomial time

The parameter estimation of moving-average (MA) signals from second-order statistics was deemed for a long time to be a difficult nonlinear problem for which no computationally convenient and reliable solution was possible. We show how the problem of MA parameter estimation from sample covariances can be formulated as a semidefinite program that can be solved in a time that is a polynomial function of the MA order. Two methods are proposed that rely on two specific (over) parametrizations of the MA covariance sequence, whose use makes the minimization of a covariance fitting criterion a convex problem. The MA estimation algorithms proposed here are computationally fast, statistically accurate, and reliable. None of the previously available algorithms for MA estimation (methods based on higher-order statistics included) shares all these desirable properties. Our methods can also be used to obtain the optimal least squares approximant of an invalid (estimated) MA spectrum (that takes on negative values at some frequencies), which was another long-standing problem in the signal processing literature awaiting a satisfactory solution     

High level of antimicrobial resistance in Campylobacter jejuni isolated from broiler chickens in Estonia in 2005 and 2006

The development of antimicrobial resistance in Campylobacter jejuni and Campylobacter coli is a matter of increasing concern. Because campylobacteriosis is transmitted to humans usually via food of animal origin, the presence of antimicrobial-resistant campylobacters in broiler chickens has important public health implications. The aim of our study was to analyze resistance patterns of C. jejuni isolated from fecal samples collected at a large Estonian chicken farm, from cecal contents collected at slaughterhouses, and from meat samples collected at the retail establishments in 2005 and 2006. A total of 131 C. jejuni isolates were collected over a 13-month period and tested by the broth microdilution VetMIC method (National Veterinary Institute, Uppsala, Sweden) to determine the MICs of various antimicrobials. Resistance to one or more antimicrobials was detected in 104 (79.4%) of the 131 isolates. High proportions of the isolates were resistant to enrofloxacin (73.3%) and nalidixic acid (75.6%). Multidrug resistance (resistance to three or more unrelated antimicrobials) was detected in 36 isolates (27.5%), all of which were resistant to enrofloxacin. Multidrug resistance was significantly associated with enrofloxacin resistance (P < 0.01), and the use of enrofloxacin may select for multiresistant strains.     

Effect of the factor inhibiting germinal vesicle breakdown on the disruption of gap junctions and cumulus expansion of pig cumulus-oocyte complexes cultured in vitro

The present study was undertaken to explore the regulatory mechanisms for meiotic resumption of pig cumulus-oocyte complexes (COCs) by assessing the nuclear status of oocytes, the degree of gap junction cell-to-cell communication and cumulus expansion after culture of various numbers of COCs in 10 microl droplets of medium for 24 h. Gap junction communication was examined by confocal laser scanning microscopy after injection of a fluorescent dye, lucifer yellow, into the oocytes. When one, three or six COCs were cultured in a 10 microl droplet, germinal vesicle breakdown was observed in > 70% of oocytes; increasing the number of COCs in a droplet further actually decreased the proportion of oocytes undergoing germinal vesicle breakdown (10 COCs: 49%; 20 COCs: 21%; 40 COCs: 13%). When six COCs were cultured in a 10 microl droplet of conditioned medium (prepared previously by culturing 20 intact and oocytectomized COCs for 24 h), the proportion of oocytes undergoing germinal vesicle breakdown was significantly reduced compared with the proportion in fresh medium. An increase in the proportion of category 1 COCs (all gap junctions within cumulus cells and between cumulus cells and oocyte are functionally maintained) was achieved by increasing the number of COCs cultured in a 10 microl droplet. The addition of conditioned medium to the fresh medium at a concentration of 50% significantly inhibited cumulus expansion. From these results, it is concluded that the factors secreted by cumulus cells regulate the disruption of gap junctions and cumulus expansion, and concurrently control the incidence of germinal vesicle breakdown in pig COCs.     

Application of Genetic Programming in Stage Hydrograph Routing of Open Channels

Routing is a technique used to simulate and predict changes in water flow along a river or channel. There are several hydraulic flow routing methods that model channel flow with high accuracy using lots of data related to channel geometry and specifications, thus making calculations very expensive. In contrast, hydrologic methods are techniques that simplify the calculation of flow conditions in a channel reach. In this paper, a stage hydrograph is modeled in simple and compound channels by genetic programming (GP) as a hydrologic method that does not depend on channel geometry and specifications, channel shape, and modeling time step. Routed hydrographs for simple and compound channels are then compared with a river analysis system model (HEC-RAS) and a coupled characteristic-dissipative-Galerkin procedure in one-dimension (CCDG-1D) as the hydraulic methods, respectively. Results show that the sum of squared differences (SSD) between a stage hydrograph by GP and modeled hydrographs by HEC-RAS and CCDG-1D methods, respectively, are not considerable in simple and compound channels. Moreover, GP is a capable tool to route an acceptable stage hydrograph even by using less geometry specification and time intervals in the detected stage. Those results indicate that the proposed GP method is effective in routing a stage hydrograph.     

Fine Tuning of 3D LTCC Inductor Properties Using Combination of Different Ferrite and Dielectric Tapes

Presented research offers solutions for properties alternation of 3D LTCC inductors by variation of materials implemented for their fabrication. Investigated geometry is solenoid‐shape micro‐inductor. Two types of dielectric cores are applied to achieve increase of quality factor for over 40% at GHz range. Five different stacks of ferrite material combinations are implemented when either fine inductance adjustments are needed or in cases when higher quality factor is required at MHz range frequencies. Increase of starting inductance of solid dielectric core solenoid is realized in tuning range of (35–60) %. Different ferrite core configurations can double quality factor maximum.     

Headspace volatiles from frozen berries of sea buckthorn (Hippophaë rhamnoides L.) varieties

The volatile compounds of frozen berries of seven sea buckthorn (Hippophaë rhamnoides L.) varieties of two growing seasons were isolated with solid phase microextraction (SPME), and analyzed with gas chromatography mass spectrometry. A total of 45 volatiles were identified from the headspace. The most numerous compounds found were esters of short chain normal or branched alcohols and acids. Ethyl 2-methylbutanoate, ethyl 3-methylbutanoate, ethyl hexanoate, 3-methylbutyl 3-methylbutanoate, ethyl octanoate and 3-methylbutyl hexanoate were the most abundant compounds identified, and they contribute over 70% of the total peak area found in samples. Principal component analysis (PCA) showed differences between the years studied as well as between varieties. Raisa of ssp. rhamnoides origin had the highest variance in the volatile profile compared to the varieties of ssp. mongolica origin.     

Nitrous oxide emissions from a municipal landfill

The first measurements of nitrous oxide (N20) emissions from a landfill by the eddy covariance method are reported. These measurements were compared to enclosure emission measurements conducted at the same site. The average emissions from the municipal landfill of the Helsinki Metropolitan Area were 2.7 mg N m(-2) h(-1) and 6.0 mg N m(-2) h(-1) measured bythe eddy covariance and the enclosure methods, respectively. The N20 emissions from the landfill are about 1 order of magnitude higher than the highest emissions reported from Northern European agricultural soils, and 2 orders of magnitude higher than the highest emissions reported from boreal forest soils. Due to the small area of landfills as compared to other land-use classes, the total N20 emissions from landfills are estimated to be of minor importance for the total emissions from Finland. Expressed as a greenhouse warming potential (GWP100), the N2O emissions make up about 3% of the total GWP100 emission of the landfill. The emissions measured by the two systems were generally of similar magnitude, with enclosure measurements showing a high small-scale spatial variation.     

Diffusion coefficient of the protein in various crystallization solutions: The key to growing high-quality crystals in space

The diffusion coefficients of lysozyme and alpha-amylase were measured in the various polyethylene glycol (PEG) solutions. Obtained diffusion coefficients were studied with the viscosity coefficient of the solution. It was found that the diffusion process of the protein was suppressed with a factor of v^γ, where ν is a relative viscosity coefficient of the PEG solution. The value of γ is ?0.64 at PEG1500 for both proteins. The value increased to ?0.48 at PEG8000 for lysozyme, while decreased to ?0.72 for alpha-amylase. The equation of an approximate diffusion coefficient at certain PEG molecular weight and concentration was roughly obtained.