13 research outputs found
Exact Solution of the Discrete (1+1)-dimensional RSOS Model with Field and Surface Interactions
We present the solution of a linear Restricted Solid--on--Solid (RSOS) model
in a field. Aside from the origins of this model in the context of describing
the phase boundary in a magnet, interest also comes from more recent work on
the steady state of non-equilibrium models of molecular motors. While similar
to a previously solved (non-restricted) SOS model in its physical behaviour,
mathematically the solution is more complex. Involving basic hypergeometric
functions , it introduces a new form of solution to the lexicon of
directed lattice path generating functions.Comment: 10 pages, 2 figure
Degenerate flag varieties: moment graphs and Schr\"oder numbers
We study geometric and combinatorial properties of the degenerate flag
varieties of type A. These varieties are acted upon by the automorphism group
of a certain representation of a type A quiver, containing a maximal torus T.
Using the group action, we describe the moment graphs, encoding the zero- and
one-dimensional T-orbits. We also study the smooth and singular loci of the
degenerate flag varieties. We show that the Euler characteristic of the smooth
locus is equal to the large Schr\"oder number and the Poincar\'e polynomial is
given by a natural statistics counting the number of diagonal steps in a
Schr\"oder path. As an application we obtain a new combinatorial description of
the large and small Schr\"oder numbers and their q-analogues.Comment: 25 page
Encouraging female entrepreneurship in Jordan: environmental factors, obstacles and challenges
The number of female entrepreneurs and their contribution to the economy is steadily rising. Yet research suggests that female entrepreneurs face more challenges and barriers than their male counterparts. This is expected to be even more prevalent in Islamic contexts, which are characterised by conservative and patriarchal societies. In this research, 254 female business students from a private and a public university responded to a questionnaire that gauges their perceptions about potential barriers to entrepreneurship in Jordan and whether the business education they are receiving helps to prepare them for future entrepreneurial activity. Our results help to form a basis on which a deeper understanding of the phenomena can be achieved through more in depth future research. Among the main environmental factors that worry potential female entrepreneurs are the weakness of Jordanian economy, lack of finance, fear of risk, gender inequality and inability to maintain a work and private life balance. Our results also show that students are really not aware of the opportunities available to them and are unable to make a proper assessment. We call on both universities and the Jordanian government to put more emphasis on practical entrepreneurial education and encouraging women to play a much more active role within the workforce
NERONE: Neural Robust Scheduling Evaluator"
ICAMES2003, ENSO, Bogazici University, Istanbu
Planet populations inferred from debris discs: insights from 178 debris systems in the ISPY, LEECH and LIStEN planet-hunting surveys
We know little about the outermost exoplanets in planetary systems, because
our detection methods are insensitive to moderate-mass planets on wide orbits.
However, debris discs can probe the outer-planet population, because dynamical
modelling of observed discs can reveal properties of perturbing planets. We use
four sculpting and stirring arguments to infer planet properties in 178
debris-disc systems from the ISPY, LEECH and LIStEN planet-hunting surveys.
Similar analyses are often conducted for individual discs, but we consider a
large sample in a consistent manner. We aim to predict the population of
wide-separation planets, gain insight into the formation and evolution
histories of planetary systems, and determine the feasibility of detecting
these planets in the near future. We show that a `typical' cold debris disc
likely requires a Neptune- to Saturn-mass planet at 10-100 au, with some
needing Jupiter-mass perturbers. Our predicted planets are currently
undetectable, but modest detection-limit improvements (e.g. from JWST) should
reveal many such perturbers. We find that planets thought to be perturbing
debris discs at late times are similar to those inferred to be forming in
protoplanetary discs, so these could be the same population if newly formed
planets do not migrate as far as currently thought. Alternatively, young
planets could rapidly sculpt debris before migrating inwards, meaning that the
responsible planets are more massive (and located further inwards) than
debris-disc studies assume. We combine self-stirring and size-distribution
modelling to show that many debris discs cannot be self-stirred without having
unreasonably high masses; planet- or companion-stirring may therefore be the
dominant mechanism in many (perhaps all) debris discs. Finally, we provide
catalogues of planet predictions, and identify promising targets for future
planet searches.Comment: 41 pages, 16 figures, accepted for publication in A&
Hole-free Partially Directed Animals
We consider the class of hole-free partially directed animals. This is the class of all polyominoes P such that every cell of P can be reached from any cell in the first column of P with a path (inside P) which makes only North, South and East steps, and such that there is not a finite region of empty unitary squares which is surrounded by cells belonging to P. We provide a generation algorithm that allows us to enumerate in constant amortized time using O(n) space