Graph pebbling has its origin in number theory. It is a model for the transportation of resources. Starting with a pebble distribution on the vertices of a simple connected graph, a pebbling move removes two pebbles from a vertex and adds one pebble at an adjacent vertex. We can think of the pebbles as fuel containers. Then the loss of the pebble during a move is the cost of transportation. A v...

Made possible by the collection of on-board tailpipe emissions data, this research identifies road and driver factors that are associated with a relatively understudied tailpipe pollutant from lightduty vehicles: ultrafine particle number emissions. High emission events (HEE) of ultrafine particle number (PN) emissions occurred most frequently at locations with steep upgrades or locations that ...

OBJECTIVES The role of pelvic lymphadenectomy in patients with lymph node-negative bladder cancer at radical cystectomy (RC) has not yet been examined in detail. We retrospectively reviewed patients who underwent RC with pelvic lymphadenectomy for bladder cancer from January 1987 to March 2008. METHODS We identified consecutive data on 169 patients who underwent RC for bladder cancer. The mea...

The cutwidth problem is to nd a linear layout of a network so that the maximal number of cuts (cw) of a line separating consecutive vertices is minimized. A related and more natural problem is the cyclic cutwidth (ccw) when a circular layout is considered. The main question is to compare both measures cw and ccw for speciic networks, whether adding an edge to a path and forming a cycle reduces ...

BACKGROUND Partner notification (PN) among individuals newly diagnosed with HIV/STI is seen as a vital tool to identify others at risk of infection. However, hardly any data are available on the effectiveness of PN on HIV/STI transmission in the Netherlands. This study aims to fill this gap by assessing current PN practices, case-finding effectiveness, and determinants of being notified among m...

Pityriasis rosea (PR) is an acute, self-limiting papulosquamous exanthem. A number of atypical variants of PR, regarding morphology and distribution of the lesions or severity of the symptoms, may be observed. Herein, we present the first case of atypical PR with hypopigmented lesions and a target-shape herald patch.

We present a new method for the interpolation of given data points and associated normals with surface parametric patches with rational normal fields. We give some arguments why a dual approach is the most convenient for these surfaces, which are traditionally called Pythagorean normal vector (PN) surfaces. Our construction is based on the isotropic model of the dual space to which the original...

PURPOSE The effects of partial nephrectomy (PN) on postoperative blood pressure (BP) are not known, and PN has the potential to worsen BP. We therefore sought to determine whether PN alters postoperative BP. MATERIALS AND METHODS Patients who underwent PN for suspected malignancy at our institution from 2002 to 2008 were included. Data on BP and medication from before and after PN were retrie...