14,664 research outputs found
On the Oß-hull of a planar point set
© 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/We study the Oß-hull of a planar point set, a generalization of the Orthogonal Convex Hull where the coordinate axes form an angle ß. Given a set P of n points in the plane, we show how to maintain the Oß-hull of P while ß runs from 0 to p in T(n log n) time and O(n) space. With the same complexity, we also find the values of ß that maximize the area and the perimeter of the Oß-hull and, furthermore, we find the value of ß achieving the best fitting of the point set P with a two-joint chain of alternate interior angle ß.Peer ReviewedPostprint (author's final draft
What are Some Best Practices in Assessing Employee Performance Without Using Performance Reviews?
[Excerpt] A 2014 Deloitte Survey reported that 58% of organizations believed that performance appraisals were an ineffective use of time. This finding carries great significance given a typical manager spends on average 210 hours a year working on appraisals. Due to the incongruence between time spent and value, many companies are eliminating formal reviews. Some companies are opting to eliminate ratings all together while others are choosing to eliminate the numerical/ranking component of the appraisal. Case studies that include outcomes are a useful tool in examining how this pertains to the management of low performers
What are Benefits and Pitfalls of Using Technical Selection Tests During the Hiring Process?
[Excerpt] Talent Acquisition departments are the frontline soldiers in the war for talent. Selection tests and simulations are common mechanisms by which firm’s filter through potential job candidates. Nevertheless, a 2017 Deloitte survey reported that 71% of firms believed they were weak in their ability to use these tools effectively. Using assessments is a balancing act between false positives (hiring the wrong candidate) and false negatives (rejecting the right candidate). As such it is important to understand the benefits and pitfalls. This is especially true with technical assessments for coders and programmers
Temperature dependence of the microscopic structure and density anomaly of the SPC/E and TIP4P-Ew water models. Molecular dynamics simulation results
We have investigated temperature trends of the microscopic structure of the
SPC/E and TIP4P-Ew water models in terms of the pair distribution functions,
coordination numbers, the average number of hydrogen bonds, the distribution of
bonding states of a single molecule as well as the angular distribution of
molecules by using the constant pressure molecular dynamics simulations. The
evolution of the structure is put in correspondence with the dependence of
water density on high temperatures down to the region of temperatures where the
system becomes supercooled. It is shown that the fraction of molecules with
three and four bonds determine the maximum density for both models. Moreover,
the temperature dependence of the dielectric constant is obtained and analyzed.Comment: 11 pages, 5 figure
Fermions in odd space-time dimensions: back to basics
It is a well known feature of odd space-time dimensions that there exist
two inequivalent fundamental representations and of the Dirac gamma
matrices. Moreover, the parity transformation swaps the fermion fields living
in and . As a consequence, a parity invariant Lagrangian can only be
constructed by incorporating both the representations. Based upon these ideas
and contrary to long held belief, we show that in addition to a discrete
exchange symmetry for the massless case, we can also define chiral symmetry
provided the Lagrangian contains fields corresponding to both the inequivalent
representations. We also study the transformation properties of the
corresponding chiral currents under parity and charge conjugation operations.
We work explicitly in 2+1 dimensions and later show how some of these ideas
generalize to an arbitrary number of odd dimensions.Comment: 8 pages, no figure
Local and global electrochemical impedances applied to the corrosion behaviour of an AZ91 magnesium alloy
The electrochemical behaviour of an AZ91 magnesium alloy was investigated in a low aggressive medium by means of local and global electrochemical impedance measurements. The results were compared to those obtained on a pure magnesium sample. It was possible to show the individual contribution of each phase constituting the alloy, and it was observed that the corrosion mechanism of the two phases was the same, controlled by the Mg dissolution. However, local impedance diagrams clearly indicated that the kinetics dissolution of the b-phase was slower than that of the a-phase, which was in good agreement with SEM observations
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