Traveling Traders' Exchange Problem: Stochastic Modeling Framework and Two-Layer Model Identification Strategy

The Travelling Traders’ Exchange Problem (TTEP) is formalised, aiming at studying the collision-exchange systems found in various research areas. As an example of the TTEP models, a 1-D model is developed and characterised in detail. The computational stochastic simulation of the 1-D TTEP model relies on a stochastic simulation algorithm implemented based on the Monte Carlo method. A model identification framework is proposed where the money distribution in the system obtained from the stochastic model is characterised in terms of (a) standard deviation of the money redistribution; (b) its probability density function. Results indicate that the expressions of the estimated functions for (a) and (b) are tightly related to the system input conditions. The example of curve fitting on the probability density function shows how the variation of money redistribution in the system in time is driven by different values of the parameters describing the interaction mechanism

A stochastic modelling approach for the characterisation of collision exchange processes

Collision-exchange process is a common physical process where system members interact with each other to exchange materials and these individual interactions cumulatively drive a macroscopic system evolution in time. In this paper, a compartment-based stochastic model is formulated to study the collision-exchange process between members in a system. The discrete Markov analysis on the stochastic model presents the analytical results that show the independence of the system equilibrium on its initial distribution, and the derived differential equations reveal the deterministic time evolution of material amount on system members. As a specific example of a physical system that can be described via this model, a seed coating process is presented where the inter-particle coating variability is expressed by the stochastic model parameters. The promising agreement between simulation predictions and experimental results demonstrates the feasibility of stochastic modelling on the collision-exchange process and facilitates further model identification and applications to industrial processes

On Fermat's principle for causal curves in time oriented Finsler spacetimes

In this work, a version of Fermat's principle for causal curves with the same energy in time orientable Finsler spacetimes is proved. We calculate the secondvariation of the {\it time arrival functional} along a geodesic in terms of the index form associated with the Finsler spacetime Lagrangian. Then the character of the critical points of the time arrival functional is investigated and a Morse index theorem in the context of Finsler spacetime is presented.Comment: 20 pages, minor corrections, references adde

Multiple ectopic leiomyomas of the abdominal rectus muscles after gasless laparoscopic uterine myomectomy

To describe and analyze the first case of multiple ectopic leiomyomas of the abdominal rectus muscles in a patient who had undergone gasless laparoscopic uterine myomectomy (GLM) 10 years before

Polyamide 11-Carbon Nanotubes Nanocomposites: Preliminary Investigation

The objective of this research is to develop an improved polyamide 11 (PA11) polymer with enhanced flame retardancy, thermal, and mechanical properties for selective laser sintering (SLS) rapid manufacturing. In the present study, a nanophase was introduced into polyamide 11 via twin screw extrusion. Arkema Rilsan® polyamide 11 molding polymer pellets were used with 1, 3, 5, and 7 wt% loadings of Arkema’s GraphistrengthTM multi-wall carbon nanotubes (MWNTs) to create a family of PA11-MWNT nanocomposites. Transmission electron microscopy and scanning electron microscopy were used to determine the degree and uniformity of dispersion. Injection molded test specimens were fabricated for physical, thermal, mechanical properties, and flammability measurements. Thermal stability of these polyamide 11-MWNT nanocomposites was examined by TGA. Mechanical properties such as ultimate tensile strength, rupture tensile strength, and elongation at rupture were measured. Flammability properties were also obtained using the UL 94 test method. All these different methods and subsequent polymer characteristics are discussed in this paper.Mechanical Engineerin

Daily rhythm of total activity/rest pattern in small and large domestic animals

Circadian rhythms represent an inherent property of living organ- isms that seem to guarantee an optimal functioning of the biological system, with maximum efficiency, performance and welfare.1 In mam- mals, a master clock located in the suprachiasmatic nuclei (SCN) of the hypothalamus adjusts the timing of other self-sustained oscillators in the brain and peripheral organs.2 In most species, the daily light- dark (L/D) cycle is the primary environmental stimulus (Zeitgeber) for the entrainment of the SCN pacemaker. The SCN receives light infor- mation from the retina and regulates several physiological processes by synchronizing molecular clockwork mechanisms consisted by a core group of clock genes in each cell.3 Among all physiological processes, the total locomotor activity (TLA) is one of the most susceptible to the L/D cycle. Light acutely suppresses locomotor activity in nocturnal (night active) animals such as rats and owls but promotes activity in diurnal (day active) animals like dogs and eagles.4 Since animals have a species-typical organization of activity patterns,5 the aim of this study was to compare the TLA in small and large domestic animals like rabbits, cats, dogs, goats, sheep, cows, donkeys and horses. Five clini- cally healthy female subjects from eight different species: rabbits (body weight 2.5±0.2 kg), cats (body weight 4.5±0.3 kg), dogs (body weight 13.5±1 kg), goats (body weight 40±2 kg), sheep (body weight 45±2 kg), cows (body weight 390±10 kg), donkeys (body weight 395±20) and horses (body weight 565±42) were enrolled in the study with owners consent. Animals were housed under natural photoperiod (March) 12:12 hours L/D cycle (5.30 am sunrise, 5.30 pm sunset) according to specific farm management, except for cats and dogs that lived outdoors. Water was available ad libitum and feeding was suit- able for each species. Total activity pattern was recorded for 10 days using actigraphy-based data loggers Actiwatch-Mini (Cambridge Neurotechnology Ltd, UK) placed on each animal through collars or halters according to the species. Activity was monitored with a sam- pling interval of 5 minutes. Total daily amount of activity, mount of activity during the photophase and the scotophase were calculated using Actiwatch Activity Analysis 5.06 (Cambridge Neurotechnology Ltd, UK). The Cosine peak of a rhythm (the time of the daily peak) was computed by cosinor rhythmometry6 as implement in the Actiwatch Activity Analysis 5.06 program. The temporal resolution of the locomo- tor activity data was reduced to t h bins by the averaging of all 15 data points within each 1 h bin to apply the statistical analysis. To analyze the locomotor activity a trigonometric statistical model was applied to each time series to statistically describe the periodic phenomenon, by characterizing the main rhythmic parameters according to the single cosinor procedure.6 Four rhythmic parameters were determined: mean level, amplitude, acrophase (the time at which the peak of a rhythm occurs), and robustness (strength of rhythmicity). For each animal, the mean level of the rhythm was computed as the arithmetic mean of all values in the data set (24 data points). The amplitude of the rhythm was calculated as half the maximum-minimum range of the oscilla- tion, which was computed as the difference between peak and trough. Robustness was computed as the percentage of the maximal score attained by the chi-square periodogram statistic for ideal data sets of comparable size and 24-h periodicity.7 Two-way analysis of variance (ANOVA) was used for the assessment of effects due to species and days on the daily amount of activity per 24 h. Statistical analysis showed significant differences among domestic species. The highest daily amount of activity was observed during the photophase (p<0.0001) in dogs, sheep, goats, cows, donkeys and horses, and dur- ing the scotophase (p<0.0001) in rabbits and cats. Our results show different pattern of locomotor activity in every domestic species (Figure 1), underlining a diurnal pattern of locomotor activity in dogs, goats, sheep, cows, donkeys and horses while rabbits and cats have a main nocturnal pattern. As previously observed by several authors,8-10 our study confirms that locomotor activity exhibits a robust daily rhythmicity during the photophase in dogs, cows and horses, therefore in these species the rhythm can be poorly affected by external stimuli. On the contrary, other domestic species can spontaneously shift from diur- nal to nocturnal activity pattern. Sheep with restricted night time feed- ing can shift the main bout of activity during the night8 or cats, that are considered mainly nocturnal, use to loose their rhythm when they live in symbiosis with humans.11 Therefore, the daily pattern of TLA does not depend only on L/D cycle but it can be affected by several environ- mental variables including different activities such as feeding, drink- ing, walking, grooming, playing as well as all conscious and uncon- scious movements

The peripartum period influenced the serum macromineral profile in mares

Changes in metabolic requirements during pregnancy may produce nutritional imbalances predisposing mares to pathological conditions. Therefore, we aimed to examine changes in serum macrominerals during the peripartum period in mares. Fifteen pregnant mares (Group A) were monitored starting at the 263rd day of pregnancy until the 21st day after foaling. Seven non-pregnant and non-lactating mares were used as a control group (Group B). Group A was subjected to blood sampling within 24-12 h after parturition (P) and then 7, 14 and 21 days after foaling (C1, C2, C3 weeks, respectively). Group B was subjected to regular sampling throughout the study to ensure that seasonal changes had no significant effect on studied parameters. Serum samples were analysed for serum electrolytes including sodium (NaC), potassium (KC), calcium (CaCC), phosphorus (PC), chloride (Cl) and magnesium (MgCC). Two-way repeated measures of analysis of variance (ANOVA) was applied to evaluate significant effects of peripartum on electrolyte concentrations. Group A showed a decrease in Cl concentrations (P D 0:011) after foaling and lower PC concentrations (P D 0:015) compared to Group B throughout the study. The linear regression model showed an increase in NaC concentrations (P D 0:002) and a gradual decrease in serum CaCC (P D 0:001) during pregnancy. Because the most significant changes in serum electrolytes occurred within 2 weeks before and 2 weeks after foaling, monitoring serum electrolyte concentrations would indicate whether the mare needs further mineral supplementation at this stage. The significant changes in a mare's macromineral profile that we observed over the peripartum provide enhanced knowledge about mineral interrelations and their modifications during specific physiological conditions such as late pregnancy and early postpartum

Single-incision laparoscopic adnexectomy in an obese patient with previous laparotomies

No case of single-incision laparoscopic surgery in obese patients who had previously undergone multiple midline vertical laparotomies has been described in the literature to date. Hence we report the first case of single-port laparoscopic salpingo-oophorectomy in an obese patient who was affected by a left adnexal mass and who had previously undergone 3 midline vertical laparotomies

Sex of offspring influences metabolism during early transition period in dairy cows

Abstract. A study using 20 Holstein Friesian cows was conducted to investigate the influence of calf gender on metabolism during the transition period in dairy cattle. Blood samples were collected at three time points: 2–4 days prepartum (time 1), and 1 week and 2 weeks postpartum (time 2 and time 3 respectively). Serum samples obtained were analysed for total proteins, albumin, urea, glucose, non-esterified fatty acids (NEFA) and β-hydroxybutyrate (BHB). Depending on the sex of the offspring, cows were divided into two groups: Group 1 consisted of cows with heifer offspring (n = 12) and Group 2 consisted of cows with bull offspring (n = 8). A two-way repeated measures ANOVA and t tests for unpaired data were used to analyse the pattern of studied parameters and differences between the two groups. The results indicate differences in metabolic parameters between the two groups. These results highlight the importance of considering fetal sex as a factor that influences maternal metabolism during the early transition period in dairy cows