2,594 research outputs found
Degree growth for tame automorphisms of an affine quadric threefold
In this paper, we consider the degree sequences of the tame automorphisms
preserving an affine quadric threefold. Using some valuatives estimates derived
from the work of Shestakov-Umirbaev and the action of this group on a CAT(0),
Gromov-hyperbolic square complex constructed by Bisi-Furter-Lamy, we prove that
the dynamical degrees of tame elements avoid any value strictly between 1 and
4/3. As an application, these methods allow us to characterize when the growth
exponent of the degree of a random product of finitely many tame automorphisms
is positive.Comment: This paper is part of the author's PhD thesi
The Old-Boy Network and the Quality of Entrepreneurs
We study a model of network formation and start-up financing with endogenous entrepreneurial type distribution. A hub firm admits members to its network based on signals about entrepreneurs’ types. Network membership is observable, which allows lenders to offer different interest rates to network and stand-alone entrepreneurs. We show that a network outcome can display a smaller number of high-type entrepreneurs even though the network is neither nepotistic nor informationally disadvantaged. While a welfare-improving network can emerge as a technically stable or unstable equilibrium, one that decreases welfare is always formed by a technically unstable equilibrium. However, the adverse welfare effects of a network and its corresponding type configuration may persist because ex-post high type entrepreneurs prefer to stay high type whereas those who wish to become high-type may need some time to react.entrepreneur, network, start-up financing
Development of a tabletop guidance system for educational robots
The guidance of a vehicle in an outdoor setting is typically implemented using a Real Time Kinematic Global Positioning System (RTK-GPS) potentially enhanced by auxiliary sensors such as electronic compasses, rotation encoders, gyroscopes, and vision systems. Since GPS does not function in an indoor setting where educational competitions are often held, an alternative guidance system was developed. This article describes a guidance method that contains a laser-based localization system, which uses a robot-borne single laser transmitter spinning in a horizontal plane at an angular velocity up to 81 radians per second. Sensor arrays positioned in the corners of a flat rectangular table with dimensions of 1.22 m × 1.83 m detected the laser beam passages. The relative time differences among the detections of the laser passages gave an indication of the angles of the sensors with respect to the laser beam transmitter on the robot. These angles were translated into Cartesian coordinates. The guidance of the robot was implemented using a uni-directional wireless serial connection and position feedback from the localization system. Three experiments were conducted to test the system: 1) the accuracy of the static localization system was determined while the robot stood still. In this test the average error among valid measurements was smaller than 0.3 %. However, a maximum of 3.7 % of the measurements were invalid due to several causes. 2) The accuracy of the guidance system was assessed while the robot followed a straight line. The average deviation from this straight line was 3.6 mm while the robot followed a path with a length of approximately 0.9 m. 3) The overall performance of the guidance system was studied while the robot followed a complex path consisting of 33 sub-paths. The conclusion was that the system worked reasonably accurate, unless the robot came in close proximity
EXOGENOUS CHALLENGES FOR THE TOURISM INDUSTRY IN THE BEGINNING OF THE TWENTY FIRST CENTURY
Tourism is one of the fastest growing industries in the world. Besides its sustained growth the tourism industry has shown in the first years of the twenty first century that it can deal with political, military and natural disasters. The present paper accrisis, international tourism, travel
Gender equality in Turkey
This note reviews gender equality in Turkey with a focus on the existing
legislation and programs. The issue of gender equality in Turkey is
particularly important for Turkey’s adoption of EU norms and acquis. The
main challenges in this respect are violence against women, equal
opportunities at the work place, paid and unpaid labour, hidden forms of
discrimination and access to political decision-making and
representation
The Development of a Liver Abscess after Screening Colonoscopy: A Calculated Risk?
We present the case of a patient who developed a liver abscess following screening colonoscopy. A colorectal screening program was introduced in the Netherlands in 2014 in order to reduce mortality from colorectal cancer. The patient in this report, a 63-year-old man with no significant medical history, underwent polypectomy of two polyps. Four days afterwards he presented to our emergency department with fever, nausea and vomiting. He was diagnosed with a Klebsiella pneumoniae liver abscess and was successfully treated with antibiotics for 6 weeks. This case highlights one of the risks of screening colonoscopy. Given the high number of colonoscopies due to the colorectal screening programs, we should be aware of complications in this mostly asymptomatic group of patients
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