The Traveling Salesman Problem: Deceptivley Easy to State; Notoriously Hard to Solve

The purpose of this thesis is to give an overview of the history of the Traveling Salesman Problem and to show how it has been an integral part of the development of the fields of Integer Programming, and Combinatorial Optimization. The thesis starts in the 1800s and progresses through current attempts on solutions of the problem. The thesis is not meant to describe in detail every attempt made, nor to describe an original solution, but to provide a high level overview of every solution attempt, and to guide the reader on what has been done, and what still can be done

Inter-filament Attractions Narrow the Length Distribution of Actin Filaments

We show that the exponential length distribution that is typical of actin filaments under physiological conditions dramatically narrows in the presence of (i) crosslinker proteins (ii) polyvalent counterions or (iii) depletion mediated attractions. A simple theoretical model shows that in equilibrium, short-range attractions enhance the tendency of filaments to align parallel to each other, eventually leading to an increase in the average filament length and a decrease in the relative width of the distribution of filament lengths.Comment: 5 pages, 4 figure

Transmission of trisomy decreases with maternal age in mouse models of Down syndrome, mirroring a phenomenon in human Down syndrome mothers

Genotyping Tc1. An example picture of a gel used during genotyping. Two lines refer to a Tc1 positive trisomic pup. One line refers to a disomic pup. (EPS 1781 kb

A multi-group SEIRA model for the spread of COVID-19 among heterogeneous populations

The outbreak and propagation of COVID-19 have posed a considerable challenge to modern society. In particular, the different restrictive actions taken by governments to prevent the spread of the virus have changed the way humans interact and conceive interaction. Due to geographical, behavioral, or economic factors, different sub-groups among a population are more (or less) likely to interact, and thus to spread/acquire the virus. In this work, we present a general multi-group SEIRA model for representing the spread of COVID-19 among a heterogeneous population and test it in a numerical case of study. By highlighting its applicability and the ease with which its general formulation can be adapted to particular studies, we expect our model to lead us to a better understanding of the evolution of this pandemic and to better public-health policies to control it

Normal sleep bouts are not essential for C. elegans survival and FoxO is important for compensatory changes in sleep

Additional file 6: Decreased lag-2 function does not slow vulval development. The progeny of wild type and lag-2(q420) animals raised at 25.5 °C were selected at the L4 stage, prior to lethargus entry. Vulval eversion was scored after 3 h; the percentage of animals completing vulval eversion was recorded. Significance was assessed by student’s two-tailed t-test p value < 0.5; error bars represents SEM from 3 trials. Total number of animals: wild type n = 45 and lag-2(q420) n = 42