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Search Results: 1 - 10 of 26604 matches for " Jean Philippe Marden "
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A Bioenergetic-Redox Approach to the Effect of Live Yeast on Ruminal pH during Induced Acidosis in Dairy Cow  [PDF]
Jean Philippe Marden, Corine Bayourthe, Eric Auclair, Raymond Moncoulon
American Journal of Analytical Chemistry (AJAC) , 2013, DOI: 10.4236/ajac.2013.410A1008
Abstract: The objective of this study was to evaluate the capacity of the live yeast (LY) Saccharomyces cerevisiae in optimizing ruminal pH and in understanding its mode of action during induced acidosis in dairy cow. Two non-lactating cannulated cows were used and offered twice daily a control diet (CD) consisting of 51% corn silage and 49% concentrates or a LY diet (LYD) composed of CD supplemented with 4 g of LY per cow and per day. Measurements of pH and redox potential (Eh) were continuously made at 1 h interval during an experimental period of 9 h per day. Samples of ruminal fluid were also taken at 2 h intervals for analyses of volatile fatty acids (VFA) and lactic acid. Oxygen partial pressure (logPO2) in the ruminal milieu was calculated from the Nernst equation, using either O2-H2O or lactate-propionate redox couples. The results showed an increase of 0.2 unit in ruminal pH when LYD was fed, which was accompanied by a mean difference in Eh of -20 mV with respect to CD. The logPO2 decreased significantly by 0.8 log unit for LYD when compared to CD. Concentrations of VFA and proportion of propionate were higher with LYD (114.4 mM and 17.1% total VFA) compared to CD (102.4 mM and 15.4% total VFA). Proportion of butyrate
Interaction between Live Yeast and Dietary Rumen Degradable Protein Level: Effects on Diet Utilization in Early-Lactating Dairy Cows  [PDF]
Christine Julien, Jean Philippe Marden, Eric Auclair, Raymond Moncoulon, Laurent Cauquil, Jean Louis Peyraud, Corine Bayourthe
Agricultural Sciences (AS) , 2015, DOI: 10.4236/as.2015.61001
Abstract: Four early lactating Holstein cows were used to study the effect of live yeast (LY, Actisaf® CNCM I-4407, Lesaffre Feed Additives, Marcq en Baroeul, France) supplementation on diet digestive utilization of dairy cows receiving concentrated corn silage-based diets with two rumen-degradable protein (RDP) levels. For a 33 d period, cows were fed a total mixed ration (TMR) containing an adequate level (AL) of RDP or a low level (LL, 30% below AL) by using soybean meal or tanned soybean meal, respectively: for 21 d with no LY addition followed by 12 d during which LY was added to the diet. The pH and redox potential (Eh) were recorded and ruminal fluid samples were collected over 3 consecutive days. Feces were collected individually over 48 h and individual dry matter intake (DMI) was measured for determining apparent nutrient digestibility. The effective degradability of individual feed ingredients composing both diets was evaluated with nylon bags technique. Structure of the ruminal bacterial community was studied and diversity index was calculated. Digestibility of organic matter (OM) and crude protein (CP) were lower for LL than those for AL. With LY, digestibility of OM and CP was increased: +2.4 and +0.8 points, for AL, and +3.7 and +5.9 points for LL, respectively. Live yeast reduced dietary N ruminal degradation with both AL and LL. Ruminal pH and Eh were lower with AL compared to LL: 5.95 and –167 mV vs. 6.13 and –144 mV. Live yeast increased ruminal total volatile fatty acids (VFA) (+8.6%), C2 (+10%), and C4 (+35%) contents for LL and decreased that of C3 (?9.8%) for AL. Neither the structure of bacterial populations of the rumen nor the diversity index (Shannon) was altered by treatments. Those results suggested a specific interest in using LY in RDP deficient diets for early lactating cows.
Methodology Article: Can Ruminal Reducing Power Assessed in Batch Cultures be Comparable to in Vivo Measurements?  [PDF]
Christine Julien, Jean-Philippe Marden, Annabelle Troegeler-Meynadier, Corine Bayourthe
Journal of Analytical Sciences, Methods and Instrumentation (JASMI) , 2014, DOI: 10.4236/jasmi.2014.43011

In ruminant field of digestive research, the appeal to methods of less invasive studies and reproducing the in vivo conditions is essential. The objective of the present study was to determine whether the conditions created with the proposed in vitro batch culture was an accurate reproduction of the physico-chemical and fermentative ruminal conditions observed in vivo. Two experiments were conducted to compare ruminal reducing power measured in vitro, i.e. in batch cultures or, in vivo i.e. in live animals: dairy cows at maintenance (Experiment 1) and lactating dairy cows (Experiment 2). In Experiment 1, at the beginning of incubation period, in vitro redox potential (Eh), pH and Clark’s exponent (rH) values were significantly higher than in vivo (+42 mV, +0.25 and +1.9, respectively) whereas volatile fatty acids (VFA)

Quantitative Analysis of the Relationship between Ruminal Redox Potential and pH in Dairy Cattle: Influence of Dietary Characteristics  [PDF]
Yayu Huang, Jean Philippe Marden, Chaouki Benchaar, Christine Julien, Eric Auclair, Corine Bayourthe
Agricultural Sciences (AS) , 2017, DOI: 10.4236/as.2017.87047
Abstract: The ruminal redox potential (Eh) can reflect the microbiological activity and dynamics of fermentation in the rumen. It might be an important indicator of rumen fermentation in combination with pH. However, the ruminal Eh has been rarely studied in dairy cows due to the difficulty of its measurement, and the relationship between ruminal Eh and pH is not clear. The objective of this study was to investigate the relationship between ruminal Eh and pH of dairy cows by meta-analysis of systematic measurements from different experiments. A database was constructed from 22 experiments on cannulated dairy cattle including 57 dietary treatments. The ruminal pH and Eh were measured without air contact between 0 and 8 h post-feeding. The results demonstrated a quadratic correlation between ruminal Eh and pH with a reliable within-animal variation (Eh = -1697 + 540.7 pH -47.7 pH2, nobservation = 70, nanimal = 26, P < 0.001, RMSE = 56, AIC = 597). The dietary characteristics (NDF, NDFf, OM, starch, degradable starch, soluble sugars contents, and the dietary ionic balance) influencing the ruminal pH also affected the ruminal Eh, but not always to the same extent. Some of them still influenced the relationship between ruminal Eh and pH. While the mechanism of the interaction between ruminal Eh and pH remains to be elucidated, it would be interesting to associate Eh to microbial profile, ruminal VFA concentration and milk production performance in future studies.
The Effects of a Probiotic Yeast on the Bacterial Diversity and Population Structure in the Rumen of Cattle
Eric Pinloche, Neil McEwan, Jean-Philippe Marden, Corinne Bayourthe, Eric Auclair, C. Jamie Newbold
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0067824
Abstract: It has been suggested that the ability of live yeast to improve milk yield and weight gain in cattle is because the yeast stimulates bacterial activity within the rumen. However it remains unclear if this is a general stimulation of all species or a specific stimulation of certain species. Here we characterised the change in the bacterial population within the rumen of cattle fed supplemental live yeast. Three cannulated lactating cows received a daily ration (24 kg/d) of corn silage (61% of DM), concentrates (30% of DM), dehydrated alfalfa (9% of DM) and a minerals and vitamins mix (1% of DM). The effect of yeast (BIOSAF SC 47, Lesaffre Feed Additives, France; 0.5 or 5 g/d) was compared to a control (no additive) in a 3×3 Latin square design. The variation in the rumen bacterial community between treatments was assessed using Serial Analysis of V1 Ribosomal Sequence Tag (SARST-V1) and 454 pyrosequencing based on analysis of the 16S rRNA gene. Compared to the control diet supplementation of probiotic yeast maintained a healthy fermentation in the rumen of lactating cattle (higher VFA concentration [high yeast dose only], higher rumen pH, and lower Eh and lactate). These improvements were accompanied with a shift in the main fibrolytic group (Fibrobacter and Ruminococcus) and lactate utilising bacteria (Megasphaera and Selenomonas). In addition we have shown that the analysis of short V1 region of 16s rRNA gene (50–60 bp) could give as much phylogenetic information as a longer read (454 pyrosequencing of 250 bp). This study also highlights the difficulty of drawing conclusions on composition and diversity of complex microbiota because of the variation caused by the use of different methods (sequencing technology and/or analysis).
Sobolev Spaces, Schwartz Spaces, and a Definition of the Electromagnetic and Gravitational Coupling  [PDF]
Jean-Philippe Montillet
Journal of Modern Physics (JMP) , 2017, DOI: 10.4236/jmp.2017.810100
Abstract: The concept of multiplicity of solutions was developed in [1] which is based on the theory of energy operators in the Schwartz space S-(R) and some subspaces called energy spaces first defined in [2] and [3]. The main idea is to look for solutions of a given linear PDE in those subspaces. Here, this work extends previous developments in S-(Rm)?(m∈Z+) using the theory of Sobolev spaces. Furthermore, we also define the concept of Energy Parallax, which is the inclusion of additional solutions when varying the energy of a predefined system locally by taking into account additional smaller quantities. We show that it is equivalent to take into account solutions in other energy subspaces. To illustrate the theory, one of our examples is based on the variation of Electro Magnetic (EM) energy density within the skin depth of a conductive material, leading to take into account derivatives of EM evanescent waves, particular solutions of the wave equation. The last example is the derivation of the Woodward effect [4] with the variations of the EM energy density under strict assumptions in general relativity. It finally leads to a theoretical definition of an electromagnetic and gravitational (EMG) coupling.
Discussion on the Energy Parallax and the Relationship to Perturbation Theory in Mathematical Physics  [PDF]
Jean-Philippe Montillet
Journal of Modern Physics (JMP) , 2018, DOI: 10.4236/jmp.2018.93034
Abstract: This work is a discussion on the energy parallax theory developed in [1] [2] based on the multiplicity of the solutions theorem. This theory is compared with the perturbation theory in mathematical physics. The perturbation theory uses the increment of a solution which can be formalized with a Taylor series development. With the energy parallax theory, the convergence property of the Taylor series of the energy of a system is the key to decide to include additional solutions, defined on the so-called energy spaces [2]. The development is supported using various examples in quantum mechanics (i.e. Rayleigh-Schrödinger perturbation theory) and wave theory with the Electromagnetic (EM) energy density (i.e. evanescent waves within the skin layer of a dielectric material). Finally, we discuss the Woodward effect [3] and the application of the energy parallax when assuming that the variations of EM energy density can trigger such effect within asymmetric cavities.
Counting Types of Runs in Classes of Arborescent Words  [PDF]
Jean-Philippe Labbé, Gilbert Labelle
Open Journal of Discrete Mathematics (OJDM) , 2013, DOI: 10.4236/ojdm.2013.31002
Abstract: An arborescence is a directed rooted tree in which all edges point away from the root. An arborescent word is obtained by replacing each element of the underlying set of an arborescence by an arbitrary letter of a given alphabet (with possible repetitions). We define a run in an arborescent word as a maximal sub-arborescent word whose letters are all identical. Various types of runs (e.g., runs of sizek, linear runs, etc) are studied in the context of R-enriched arborescent words, where R is a given species of structures.
Transmission of N-Atoms Produced by N2 Flowing Microwave Afterglows through Hollow Tubes  [PDF]
Andre Ricard, Jean-Philippe Sarrette
Journal of Analytical Sciences, Methods and Instrumentation (JASMI) , 2013, DOI: 10.4236/jasmi.2013.31001

Transmission of N-atoms (T N ) through small diameters tubes (1.5 and 3 mm internal diameter (i.d) and 9, 50 and 80 cm length for silicone tubes, 1.5 mm i.d and 6.5 cm length for stainless steel tubes) has been measured in late N2 and Ar-N2 flowing afterglows of microwave plasmas in continuous and pulsed gas injection at a flow rate of 1 and 3 Standard liter by minute (Slm), a gas pressure from 2 to 4 Torr for N2 and 20 Torr for Ar-1%N2 and a plasma power from 150 to 300 Watt. From the experimental TN values, it is deduced the γ-destruction probability inside the tube walls as being y = (1-1.6)×

Complex projective structures on Kleinian groups
Albert Marden
Mathematics , 1998,
Abstract: Let M^3 be a compact, oriented, irreducible, and boundary incompressible 3-manifold. Assume that its fundamental group is without rank two abelian subgroups and its boundary is non-empty. We will show that every homomorphism from pi_1(M) to PSL(2,C) which is not `boundary elementary' is induced by a possibly branched complex projective structure on the boundary of a hyperbolic manifold homeomorphic to M.
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