GIT Model Research Articles

Cohomology of the moduli space of degree two Enriques surfaces

We compute the intersection Betti numbers of the GIT model of the moduli space of numerically polarized Enriques surfaces of degree 2. The strategy of the cohomological calculation relies on a general method developed by Kirwan to compute the cohomology of GIT quotients of projective varieties, based on the equivariantly perfect stratification of the unstable points studied by Hesselink and others and a partial resolution of singularities, called Kirwan blow-up.

In vitro digestion of solid-in-oil-in-water emulsions for delivery of CaCO3

The formation of CaCO3 loaded particles based on solid/oil/water (S/O/W) emulsions is a promising method to improve the dispersion stability and digestive properties of CaCO3 in liquid foods. Used CaCO3 as solid phase, soybean oil as O phase, sodium caseinate (NaCas), gelatin (GEL), and sodium caseate-gelatin (NaCas-GEL) as W phase, S/O/W calcium-lipid microspheres were prepared. The intermolecular interactions were examined by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and X-ray diffraction (XRD) analysis. GIT model was used to analyze the particle size, Zeta-potential, and microstructure at different digestion stages by combining the fatty acid release rate, the degree of protein hydrolysis, and the release of free calcium. The FTIR and Raman and XRD results showed that NaCas interacts with GEL to a certain extent, which was helpful for the preparation of stable S/O/W emulsion and could effectively improve the embedding rate of CaCO3. GIT studies showed the addition of GEL weakened the looseness and openness of the aggregation structure in the gastric digestion stage, reduced the FFA release rate to a certain extent, and had a certain inhibitory effect on the digestion of soybean oil in the emulsion. The results showed that the digestion of S/O/W emulsion was the fastest when the W phase was NaCas, and the addition of GEL could significantly reduce the digestion.

Cohomology of the moduli space of non-hyperelliptic genus four curves

We compute the intersection Betti numbers of the GIT model of the moduli space of Brill-Noether-Petri general curves of genus 4. This space was shown to be the final non-trivial log canonical model for the moduli space of stable genus four curves, under the Hassett-Keel program. The strategy of the cohomological computation relies on a general method developed by Kirwan to calculate the cohomology of GIT quotients of projective varieties, based on the equivariantly perfect stratification of the unstable points studied by Hesselink and others and a partial resolution of singularities.

Development and implementation of the GIT-modelling bioreactor system: the way to reducing a carbon footprint

The purpose of this article is to analyze and compare the carbon footprint value between «in vivo» and «in vitro» microbiological experiments in chicken GIT. The SHIME-style bioreactor for modeling the processes occurring in the gastrointestinal tract of chickens is developed. For «in vitro» estimation – use analytic and experimental results, carrying out on developed chicken GIT model. For « in vivo» estimation, use the carbon footprint of two mounts old broiler chicken. Assessments showed that «in vitro» carbon footprint constitutes about 15% of «in vivo» one. The most significant contributors to «in vitro» carbon footprint are nutrient medium (80%), then control computer (10%), then heather (5%). Recommendations for further carbon footprint reduction for «in vitro» experiments are formulated.

On the moduli space of pairs consisting of a cubic threefold and a hyperplane

We study the moduli space of pairs (X,H) consisting of a cubic threefold X and a hyperplane H in P4. The interest in this moduli comes from two sources: the study of certain weighted hypersurfaces whose middle cohomology admit Hodge structures of K3 type and, on the other hand, the study of the singularity O16 (the cone over a cubic surface). In this paper, we give a Hodge theoretic construction of the moduli space of cubic pairs by relating (X,H) to certain “lattice polarized” cubic fourfolds Y. A period map for the pairs (X,H) is then defined using the periods of the cubic fourfolds Y. The main result is that the period map induces an isomorphism between a GIT model for the pairs (X,H) and the Baily–Borel compactification of some locally symmetric domain of type IV.

Measurements of Sea Clutter at Low Grazing Angle in Mediterranean Coastal Environment

Results of a coastal measurement campaign called MediterraneAn Rfc and cLutter ENvironmental Experiment (MARLENE) are presented and studied. The campaign was held in spring 2014, on a DGA site in the Mediterranean Sea region of Toulon, France. Three coastal measurement radar systems, Millimeter wave Experimental Multifrequency Polarimetric High Resolution Interferometric System (Fraunhofer FHR), MARSIG (WTD 71), and MEDYCIS (ONERA), were deployed to simultaneously acquire sea clutter measurements. During the campaign, the in situ oceanic and meteorological conditions were characterized from the RV PLANET meteorological ship deployed by WTD 71 and by modeling from WAVEWATCH III and SWAN wave models. Radar measurements were performed at the C-, X-, Ku-, Ka-, and W-bands. The measurement results are presented in terms of reflectivity and mean Doppler spectrum according to low grazing angle and azimuth variations. Reflectivity variations are compared with the empirical GIT model and close results are obtained at the C- and Ka-bands. At the same frequency bands, mean Doppler Spectrum velocity is presented and analyzed according to grazing and azimuth angles. Physical interpretations of electromagnetic interaction with sea surface are discussed.

Controlling the potential gastrointestinal fate of β-carotene emulsions using interfacial engineering: Impact of coating lipid droplets with polyphenol-protein-carbohydrate conjugate.

The impact of interfacial coatings comprised of polyphenol-protein-carbohydrate conjugates on the properties of nutraceutical-fortified lipid droplets during digestion was investigated. Surface-active chlorogenic acid-lactoferrin-polydextrose (CA-LF-PD) conjugate was synthesized as emulsifier to stabilize lipid droplets in β-carotene-enriched oil-in-water emulsions. Changes in droplet size, charge, and microstructure were monitored as β-carotene emulsions were passed through a simulated gastrointestinal tract model (mouth, stomach, small intestine). LF-coated droplets were unstable to flocculation at pH 8.0-9.0, due to the reduction in electrostatic repulsion, but CA-LF-PD conjugate-coated droplets were stable. Emulsions stabilized by ternary conjugate had better stability to droplet aggregation under simulated GIT conditions than other systems, which increased β-carotene bioaccessibility. The importance of including an oral phase in the simulated GIT model was also demonstrated. The ternary conjugate-stabilized emulsions developed in this study have potential applications as protectors and carriers of hydrophobic drugs, supplements and nutraceuticals.

Modified GIT model for predicting wind-speed behavior of low-grazing-angle radar sea clutter

A modified GIT model for describing the variational trend of mean clutter reflectivity as a function of wind speed is proposed. It uses two slope adjustment factors and two critical wind-speed factors to define and adjust the increasing slope of reflectivity with respect to wind speed. In addition, it uses a constant factor to compensate the overall amplitude of clutter reflectivity. The performance of the modified GIT model has been verified on the basis of the L-band low-grazing-angle radar sea clutter data. The results are in good agreement with the experimental data, indicating that the model is more effective in predicting the wind-speed behavior of clutter reflectivity than the conventional GIT model, especially for lower and higher wind speeds. We believe that the proposed model can provide deeper insights into the relationship between radar sea clutter reflectivity and sea state conditions.

An Improved Empirical Model for Radar Sea Clutter Reflectivity

A fundamental characteristic of radar sea clutter, important for radar performance evaluations, is its apparent reflectivity defined a σo (m2/m2). “Apparent” is used as a reminder that any measurement of sea clutter reflectivity includes the effects of propagation and shadowing close to the sea surface. Sea clutter reflectivity depends on many factors, including sea state, wind velocity, grazing angle, polarization, and radar frequency. An empirical sea clutter model proposed by Horst, et al. (1978), the so-called GIT model, has found widespread acceptance in the radar community. However, this model does not always agree with what is the most complete experimental database of sea clutter reflectivity available to the radar systems engineer. The 1991 edition of F. E. Nathanson's book provides seven tables of measured sea clutter reflectivity data summarized from approximately 60 sources. The large deviation between the GIT model and this database, in particular at lower sea states, has prompted NRL to develop an improved model for sea clutter reflectivity based on these tables. The model is a function of radar frequency, polarization, sea state, and grazing angle. The functional form of this empirical model was chosen such that the average absolute deviation (in dB) between the model and the experimental data was minimized.

Effect of bacteriocin-producing lactobacilli on the survival of Escherichia coli and Listeria in a dynamic model of the stomach and the small intestine

The survival of Lactobacillus curvatus LTH 1174 (bac +) and (bac −) in combination with Escherichia coli LTH 1600 or Listeria innocua DSM20649 during transit through a dynamic model of the human stomach and small intestine (GIT model) was studied. Furthermore, we determined the digestion of curvacin A during gastro-intestinal transit and the effect of this bacteriocin on microbial survival. Lb. curvatus is rapidly killed in the gastric compartment at pH<2.0, and less than 0.01% of the cells delivered to the small intestinal compartments were recovered from the ileal compartment of the model. Meat exerted a protective effect against the lethal action of bile against Lb. curvatus. The sensitivity of E. coli to acid depended on the aeration of the preculture and decreased in the order anaerobic>strongly agitated>agitated. Lactic acid and curvacin A enhanced the lethal effect of low pH on E. coli. Accordingly, cells from strongly agitated cultures were killed faster in the gastric compartment of the GIT model than those from agitated cultures, and inactivation was accelerated in the presence of curvacin A. E. coli tolerated the bile concentrations prevailing in the small intestinal compartments of the model. The survival of Listeria innocua in the GIT model was comparable to that of Lb. curvatus. The curvacin A produced by Lb. curvatus LTH1174 (bac +) killed>90% of the L. innocua within 10 min after mixing of the cultures. Curvacin A was not degraded in the the gastric compartment, and could be detected in the ileal compartment during the first 180 min upon addition of the meal.

Analyzing the preference for non-exclusive forms of telecommuting : Modeling and policy implications

This study examines three models of the individual's preference for home- and center-based telecommuting. Issues concerning the estimation of discrete models when the alternatives are non-exclusive are discussed. Two binary logit models are presented, one on the preference to telecomnmte from a center versus not telecommuting from a center (adjusted p2 = 0.24), and the other on the preference to telecommute from a center over telecommuting from home (adjusted 2 =0. 64). A nested lo git model is als o est imated on thefoll owing four alternatives: preferring not to telecommute, preferring either form of telecommuting, preferring to telecommute from home, and preferring to telecommute from a center (adjusted p: = 0.35). The results of the models illustrated the importance of attitudinal measures in measuring an individual's preference to telecommute. Oblique factor scores representing workplace interac- tion, stress, workaholism, internal control, and commute stress were staustically significant in some or all of the models. Other explanatory variables which were found to be consistently significant were education, job suitability, and age. Most respondents preferred either to telecom- mute from home or were indifferent between either form of telecommuting, which raises the question as to whether there really is a sizeable market niche to be filled by telecommutmg centers, and hence whether they may make a significant contribution to transportation demand reduction.