scholarly journals A mathematical model of weight loss under total starvation: evidence against the thrifty-gene hypothesis

2012 ◽  
Vol 6 (1) ◽  
pp. 236-251 ◽  
Author(s):  
J. R. Speakman ◽  
K. R. Westerterp
Keyword(s):  
Mathematical Model ◽  
Weight Loss ◽  
Thrifty Gene ◽  
Total Starvation

scholarly journals A multi-factorial mathematical model for the selection of electropolishing parameters with a view to reducing the environmental impact

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Paweł Lochyński ◽  
Sylwia Charazińska ◽  
Maciej Karczewski ◽  
Edyta Łyczkowska-Widłak
Keyword(s):  
Mathematical Model ◽  
Weight Loss ◽  
Stainless Steel ◽  
Current Density ◽  
Quality Parameters ◽  
Important Goal ◽  
Process Duration ◽  
Metal Processing ◽  
Selection Of

AbstractElectrochemical metal processing is a process that generates harmful pollution. An important goal often disregarded by researchers is not only the achievement of the best possible quality of electropolished surface, but also minimising the load of metal ions in the wastewater generated in the process. The conducted experiments on the electropolishing of stainless steel in laboratory conditions, varied time, temperature and current density conditions, as well as process bath contamination (ranging from 0 to 6% Fe mass) allowed us to develop a multi-factorial mathematical model. This model offers the possibility of being able to select the process parameters recommended for achieving the desired effects. It takes into account such surface quality parameters as roughness and gloss, process duration and current density that determine power consumption, as well as the weight loss of the electropolished element that influence the rate of contamination in processing baths and wastewater. The study presents the composition of a passive film of stainless steel after the electropolishing process at the initial and final stages of the process bath’s exploitation. The results obtained from XPS tests were then correlated with the results of corrosion tests and resistance to pitting corrosion in the environment of 0.1 M NaCl.

scholarly journals Mathematical Modeling of Temperature in Bread Baking

2011 ◽  
Vol 68 (2) ◽  
Author(s):  
Adriana Paula DAVID ◽  
Nicolae BURNETE ◽  
Alexandru NAGHIU ◽  
Giorgiana Mihaela CĂTUNESCU
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Model ◽  
Weight Loss ◽  
Skin Color ◽  
Color Temperature ◽  
Temperature Heating ◽  
Qualitative Characteristics

This paper aims to obtain a mathematical model to describe the evolution of temperature during the baking of bread and pastry bakers, and how these developments affect the main qualitative characteristics of the finished product such as skin color, temperature heating of the product and weight loss in cooking.

A Mathematical Model of Some Aspects of Fish Growth, Respiration, and Mortality

1967 ◽  
Vol 24 (11) ◽  
pp. 2355-2453 ◽  
Author(s):  
Erik Ursin
Keyword(s):  
Mathematical Model ◽  
Weight Loss ◽  
Oxygen Consumption ◽  
Metabolic Model ◽  
The Body ◽  
Fish Growth ◽  
Natural Mortality ◽  
Gill Area ◽  
Growth Respiration ◽  
The Difference

A simple metabolic model describing growth as the difference between what enters the body and what leaves it, is elaborated assuming that synthetic processes (the building-up, the anabolism) are consuming energy supplied by processes of decomposition (the break-down, the catabolism). This leads to partitioning total catabolism into two components, one being a function of the rate of synthesis, another keeping the body functioning independently of synthesis. The rate of synthesis is described as a function of food taken, of the efficiencies of digestion and energy conversion, and of the absorbing surface of the intestine. Catabolic processes are supposed to be functions of the oxygen concentration in the water, the absorbing surface of the gills, and the rate of oxygen transport. Both kinds of processes are made functions of temperature in the way enzymatic processes usually are. Assuming that molecular interactions accidentally go wrong makes natural mortality, like growth, a function of the rates of anabolic and catabolic processes and body size.Application of the model to data of length-at-age, food and oxygen consumption, weight loss, gill area, and natural mortality indicates that at least some of the main hypotheses cannot be rejected on available evidence.

scholarly journals Modeling for Pyrolysis of Solid Biomass

2019 ◽  
Vol 64 (2) ◽  
pp. 192-204
Author(s):  
Biljana Miljkovic ◽  
Branislava Nikolovski ◽  
Dejan Mitrović ◽  
Jelena Janevski
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Weight Loss ◽  
Degradation Mechanism ◽  
Volatile Matter ◽  
Point Of View ◽  
Experimental Results ◽  
Pyrolysis Kinetics ◽  
Heating Rates ◽  
Simulation Results

In comparison to coal, biomass is characterized by a higher content of volatile matter. It is a renewable source of energy which has many advantages from an ecological point of view. Understanding the physical phenomena of pyrolysis and representing them with a mathematical model is the primary step in the design of pyrolysis reactors. In the present study, an existing mathematical model is used to describe the pyrolysis of a single solid particle of biomass. It couples the heat transfer equations with the chemical kinetics equations. A finite difference method is used for solving the heat transfer equation and the two-step pyrolysis kinetics equations. The model equation is solved for a slab particle of equivalent dimension 0.001 m and temperature ranging from 300 to 923 K. An original numerical model for the pyrolysis of wood chips is proposed and relevant equations solved using original program realized in MATLAB.To check the validity of the numerical results, experimental results of pyrolysis of woody biomass in laboratory facility was used. The samples were heated over a range of temperature from 300 to 923 K with three different heating rates of 21, 32 and 55 K/min, and the weight loss was measured. The simulation results as well as the results obtained from thermal decomposition process indicate that the temperature peaks at maximum weight loss rate change with the increase in heating rate. The experimental results showed that the simulation results are in good agreement and can be successfully used to understand the degradation mechanism of solid reaction.

scholarly journals Can Thrifty Gene(s) or Predictive Fetal Programming for Thriftiness Lead to Obesity?

2011 ◽  
Vol 2011 ◽  
pp. 1-11 ◽  
Author(s):  
Ulfat Baig ◽  
Prajakta Belsare ◽  
Milind Watve ◽  
Maithili Jog
Keyword(s):  
Mathematical Model ◽  
Social Factors ◽  
Fetal Programming ◽  
Later Life ◽  
Thrifty Gene ◽  
Factors Affecting ◽  
Thrifty Phenotype ◽  
Obesity Research ◽  
Thrifty Genes ◽  
Periodic Starvation

Obesity and related disorders are thought to have their roots in metabolic “thriftiness” that evolved to combat periodic starvation. The association of low birth weight with obesity in later life caused a shift in the concept from thrifty gene to thrifty phenotype or anticipatory fetal programming. The assumption of thriftiness is implicit in obesity research. We examine here, with the help of a mathematical model, the conditions for evolution of thrifty genes or fetal programming for thriftiness. The model suggests that a thrifty gene cannot exist in a stable polymorphic state in a population. The conditions for evolution of thrifty fetal programming are restricted if the correlation between intrauterine and lifetime conditions is poor. Such a correlation is not observed in natural courses of famine. If there is fetal programming for thriftiness, it could have evolved in anticipation of social factors affecting nutrition that can result in a positive correlation.

scholarly journals A Mathematical Model for Estimation of Broiler Egg Weight Loss from Physical Dimensions and Air Cell Size During Incubation

1992 ◽  
Vol 71 (4) ◽  
pp. 625-630 ◽  
Author(s):  
L. PHILLIPS ◽  
J. BRAKE ◽  
S. ELLNER ◽  
RACHEL OUKAMA
Keyword(s):  
Mathematical Model ◽  
Weight Loss ◽  
Cell Size ◽  
Egg Weight ◽  
Physical Dimensions

scholarly journals A MATHEMATICAL MODEL OF GALVANIC CORROSION UNDER THE CONDITIONS OF A THIN ELECTROLYTE FILM

2016 ◽  
Vol 56 (2) ◽  
pp. 106-111
Author(s):  
Vít Jeníček ◽  
Linda Diblíková
Keyword(s):  
Mathematical Model ◽  
Weight Loss ◽  
Time Dependence ◽  
Experimental Error ◽  
Atmospheric Corrosion ◽  
Galvanic Corrosion ◽  
Experimental Results ◽  
Polarization Curves ◽  
Electrolyte Film ◽  
The Difference

<p>A mathematical model of galvanic corrosion under the conditions of a thin electrolyte film was used to evaluate atmospheric corrosion. Experimentally determined weight loss values were used to validate the modelled results. The time dependence of the corrosion degradation was included in the model using polarization curves of the corroded materials. The difference between the modelled results and the experimental results was 20%, taking the experimental error into account.</p>

scholarly journals Novel Mathematical Model for Kinetic of Weight Loss of Plastic Under Isothermal Conditions.

2017 ◽  
Vol 13 (02) ◽  
pp. 60-67
Author(s):  
L.P.S. Rohitha ◽  
S.S.N. Perera ◽  
M.A.B. Prashantha
Keyword(s):  
Mathematical Model ◽  
Weight Loss ◽  
Isothermal Conditions

Live weight loss and its components in Romney ewes subjected to L-thyroxine therapy and a low plane of nutrition. Part II. Effects on some non-carcass components of live weight

1958 ◽  
Vol 51 (3) ◽  
pp. 282-288 ◽  
Author(s):  
A. H. Kirton ◽  
R. A. Barton
Keyword(s):  
Weight Loss ◽  
Gastrointestinal Tract ◽  
Alimentary Tract ◽  
Combined Treatment ◽  
Live Weight ◽  
Thyroxine Therapy ◽  
Fat Depots ◽  
Thyroxine Treatment ◽  
Mesenteric Fat ◽  
Total Starvation

1. The effects of l-thyroxine therapy and a low plane of nutrition on some of the non-carcass components of live weight in New Zealand Romney ewes were investigated.2. Thyroxine treatment significantly lowered the weight of the gastrointestinal tract contents. A low plane of nutrition and a longer total starvation immediately pre-slaughter had little effect in lowering the weight of the gastrointestinal contents. Alimentary tract ‘fill’ accounted for a group mean loss of live weight of up to 5 lb.3. Thyroxine treatment lowered the weight of the empty gastric tract, while a low plane of nutrition reduced the weight of both the empty gastric and intestinal tracts. The combined treatment effects accounted for a loss of up to 3 lb. in the weight of the empty gastrointestinal tract.4. Neither treatment significantly reduced the weight of the omental and mesenteric fat depots.5. The weight of the thyroid gland was unaffected by either treatment.6. A low plane of nutrition significantly reduced the weight of the liver, kidneys and the heart but had no effect on the weight of the spleen. Thyroxine therapy significantly reduced the weight of the liver and tended to increase the weight of the kidneys and the heart.

scholarly journals Calculation of dependences for estimating the amount of weight loss during lyophilization of diagnostic preparations

2020 ◽  
Vol 10 (3) ◽  
pp. 506-514
Author(s):  
A. V. Komissarov ◽  
D. N. Bibikov ◽  
S. A. Badarin ◽  
N. V. Sinitsyna ◽  
N. I. Kostyleva ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Weight Loss ◽  
Statistical Processing ◽  
Model Solution ◽  
Drying Temperature ◽  
Amount Of Substance ◽  
Proposed Model ◽  
Time Parameters ◽  
Reducing Costs ◽  
Full Factorial

In this study, we aimed to calculate dependencies for assessing the value of weight loss during lyophilization of diagnostic preparations depending on the drying temperature and time. A model solution for lyophilization was Hottinger broth with gelatin (1.5%) and peptone (10%) used as stabilizers. To achieve the aim, a full factorial experiment 23 was planned and implemented, the investigated factors in which were the temperature and time of final drying, as well as the amount of substance in the primary packaging. Using ampoules as containers for primary packaging, a regression equation was obtained. The conducted statistical processing of the obtained equation showed the feasibility of the developed mathematical model. According to the model, an increase in the drying temperature and time leads to a decrease in the amount of weight loss; however, weight loss increases under an increase in the amount of substance in the secondary packaging. As a result of the experiments, a correspondence between the experimental and calculated values of weight loss during drying was revealed. The effect of the height of the material under drying on the weight loss was studied when drying an equivalent amount of substance in vials. The developed mathematical model for drying in ampoules was modified to describe the process of lyophilization in vials. The experimental results confirmed the possibility of calculating weight loss during drying using the proposed model. The developed dependencies can be used for estimating the value of weight loss during lyophilization of various substances, which is of particular importance in terms of reducing costs when establishing the temperature and time parameters of drying new biological products and modifying production regimes when changing the amount of product, type of primary packaging or desorption conditions.

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