Occupational exposure to glass wool fibers: An update.

In the decade since the last published comprehensive report of occupational exposures in the glass wool insulation industry, many process and regulatory changes have occurred in the glass wool manufacturing sector. This paper assesses whether any significant changes in worker exposures to glass wool fibers have resulted from these process and regulatory changes. The analysis compares worker exposures to glass wool overall and across different product and job categories in the manufacturing sector prior to and after 2007, the data cutoff period for the last comprehensive update of occupational exposures in this industry.

Rigidity for sticky discs.

We study the combinatorial and rigidity properties of disc packings with generic radii. We show that a packing of discs in the plane with generic radii cannot have more than 2 - 3 pairs of discs in contact. The allowed motions of a packing preserve the disjointness of the disc interiors and tangency between pairs already in contact (modelling a collection of sticky discs).

Periodic planar disc packings.

Several conditions are given when a packing of equal discs in a torus is locally maximally dense, where the torus is defined as the quotient of the plane by a two-dimensional lattice. Conjectures are presented that claim that the density of any collectively jammed packing, whose graph does not consist of all triangles, and the torus lattice is the standard triangular lattice, is at most (n/(n + 1))π√12, where n is the number of packing discs in the torus. Several classes of collectively jammed packings are presented where the conjecture holds.

Applications and findings of an occupational exposure database for synthetic vitreous fibers.

Occupational exposure databases are being used increasingly to characterize worker exposures in industries involving a variety of exposure scenarios. The glass and rock/slag segments of the synthetic vitreous fiber industry (in the United States) has developed a large (>14,000 samples) exposure database that can be used to estimate worker exposures based on industry sector, fiber type, product type, and job function. This article describes the development of this database as part of an industry-Occupational Safety and Health Administration collaborative Health and Safety Partnership Program and summarizes the findings and potential applications of the database.

Underconstrained jammed packings of nonspherical hard particles: ellipses and ellipsoids.

Continuing on recent computational and experimental work on jammed packings of hard ellipsoids [Donev, Science 303, 990 (2004)] we consider jamming in packings of smooth strictly convex nonspherical hard particles. We explain why an isocounting conjecture, which states that for large disordered jammed packings the average contact number per particle is twice the number of degrees of freedom per particle (Z[over]=2d{f}) , does not apply to nonspherical particles. We develop first- and second-order conditions for jamming and demonstrate that packings of nonspherical particles can be jammed even though they are underconstrained (hypoconstrained, Z[over]<2d{f}).

The Premature Infants in Need of Transfusion (PINT) study: a randomized, controlled trial of a restrictive (low) versus liberal (high) transfusion threshold for extremely low birth weight infants.

Objective: To determine whether extremely low birth weight infants (ELBW) transfused at lower hemoglobin thresholds versus higher thresholds have different rates of survival or morbidity at discharge.

Study Design: Infants weighing <1000 g birth weight were randomly assigned within 48 hours of birth to a transfusion algorithm of either low or high hemoglobin transfusion thresholds. The composite primary outcome was death before home discharge or survival with any of either severe retinopathy, bronchopulmonary dysplasia, or brain injury on cranial ultrasound.

A comparison of high and standard blood transfusion volumes in premature infants.

Unlabelled: We compared high volume (20 ml/kg) with standard volume (15 ml/kg) packed red blood cell (PRBC) transfusions in a randomized trial. Ten high volume babies received a mean of 2.8 transfusions, while 10 standard volume babies received a mean of 3.

Comment on "Jamming at zero temperature and zero applied stress: The epitome of disorder".

Phys. Rev. E.

Improving the density of jammed disordered packings using ellipsoids.

Packing problems, such as how densely objects can fill a volume, are among the most ancient and persistent problems in mathematics and science. For equal spheres, it has only recently been proved that the face-centered cubic lattice has the highest possible packing fraction phi=pi/18 approximately 0.74.