Adolescent Adjustment Before and After HIV-Related Parental Death.

The impact of HIV-related parental death on 414 adolescents was examined over a period of 6 years. The adjustment of bereaved adolescents was compared over 4 time periods relative to parental death and was also compared with the adjustment of nonbereaved adolescents. Bereaved adolescents had significantly more emotional distress, negative life events, and contact with the criminal justice system than nonbereaved youths; these behaviors did not remain significantly higher after parental death. Depressive symptoms and passive problem solving increased soon after parental death, as compared with nonbereaved adolescents. One year subsequent to parental death, depression and passive problem solving were similar to the levels of nonbereaved peers. Only sexual risk behaviors increased following parental death. These results suggest the importance of early family intervention soon after parental HIV diagnosis, prior to parental death, and sustained over time. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analysis of the flavonoid component of bioactive New Zealand mānuka (Leptospermum scoparium) honey and the isolation,characterisation and synthesis of an unusual pyrrole

The flavonoid components of New Zealand mānuka (Leptospermum scoparium) honey have been quantified in a series of 31 honeys of varying non-peroxide antibacterial activity to clarify discrepancies between previous studies reported in the literature. Total flavonoid content was 1.16 mg/100 g honey. The principal flavonoids present were pinobanksin, pinocembrin, luteolin and chrysin and together these represented 61% of the total flavonoid content. 1, 2-formyl-5-(2-methoxyphenyl)-pyrrole, which was weakly correlated with the non-peroxide antibacterial activity, was isolated from the flavonoid fraction and separately synthesised. 1 did not display inhibitory activity against Staphylococcus aureus in vitro and thus the origin of the correlation, which is still unknown, is not a direct contribution.     

A refined search tree technique for Dominating Set on planar graphs

We establish a refined search tree technique for the parameterized DOMINATING SET problem on planar graphs. Here, we are given an undirected graph and we ask for a set of at most k vertices such that every other vertex has at least one neighbor in this set. We describe algorithms with running times O(8^kn) and O(8^kk+n³), where n is the number of vertices in the graph, based on bounded search trees. We describe a set of polynomial time data-reduction rules for a more general “annotated” problem on black/white graphs that asks for a set of k vertices (black or white) that dominate all the black vertices. An intricate argument based on the Euler formula then establishes an efficient branching strategy for reduced inputs to this problem. In addition, we give a family examples showing that the bound of the branching theorem is optimal with respect to our reduction rules. Our final search tree algorithm is easy to implement; its analysis, however, is involved.     

Crystal structures of a single coiled-coil peptide in two oligomeric states reveal the basis for structural polymorphism

Each protein sequence generally adopts a single native fold, but the sequence features that confer structural uniqueness are not well understood. To define the basis for structural heterogeneity, we determined the high resolution X-ray crystal structures of a single GCN4 leucine-zipper mutant (Asn 16 to aminobutyric acid) in both dimeric and trimeric coiled-coil conformations. The mutant sequence is accommodated in two distinct structures by forming similarly-shaped packing surfaces with different sets of atoms. The trimer structure, in comparison to a previously-characterized trimeric mutant with substitutions in eight core residues, shows that the twist of individual helices and the helix-helix crossing angles can vary significantly to produce the most favoured packing arrangement.     

Graph separators: a parameterized view

Graph separation is a well-known tool to make (hard) graph problems accessible to a divide-and-conquer approach. We show how to use graph separator theorems in combination with (linear) problem kernels in order to develop fixed parameter algorithms for many well-known NP-hard (planar) graph problems. We coin the key notion of glueable select&verify graph problems and derive from that a prospective way to easily check whether a planar graph problem will allow for a fixed parameter algorithm of running time for constant c. One of the main contributions of the paper is to exactly compute the base c of the exponential term and its dependence on the various parameters specified by the employed separator theorem and the underlying graph problem. We discuss several strategies to improve on the involved constant c.     

Stress dependency of the Cerchar abrasivity index (CAI) and its effects on wear of selected rock cutting tools

The abrasiveness of rocks is often described by the Cerchar abrasivity index CAI. However, the state of stress of the rock sample with the standard CAI test in the laboratory is different from the state of stress of rock to be excavated at the face of any underground opening. Until this work, no attempt has been made to estimate if and how the CAI is effected by in situ stresses. This paper demonstrates that the CAI is definitely stress-dependent. A novel test procedure in which the CAI tests is conducted on samples in a triaxial cell shows the stress dependency for various rock types by higher CAI values upon confining pressure. Additionally, the states of stress at the face of different underground openings are discussed and application of the elevated CAI values for estimating wear of roadheader picks and TBM discs is given.     

Analyses of acoustic emission response of a fault breccia in uniaxial deformation

Interpretation of mechanical tests on block-in-matrix rocks (bimrocks) is difficult and often open to dispute as, with deformation, the interactions between blocks, matrix and pores are complex, reflecting the influence of their different shape, size, strength and stiffness. The acoustic emission (AE) technique can be used to record an ultrasound pulse emitted by a defect within the sample at the moment of its occurrence. Typically several deformations occur, such as crack closure, crack initiation or permanent crack damage, but they may be difficult to visualize with a fault breccia. Consequently, with fault breccia it is advisable to focus on the primary stage of deformation where the acoustic emission response may be traced to properties of the breccia, such as block proportions. The paper shows that the different geometrical properties, particularly the volumetric block proportions, are reflected by stress concentrations which in turn trigger specific AE signatures.     

Cerebral air embolism after central venous catheter

Introduction of air into the arterial circulation can cause cerebral air embolism, leading to severe neurological deficits. A case is reported on a patient suffering from fatal cerebral air embolism after a subclavian vein catheter had been inserted. The risks associated with inserting and removing central venous catheters are described. Apart from the pathogenesis of a paradoxical air embolism in a patient with a right-to-left shunt due to a patent foramen ovale, air embolism can occur if a large amount of air traverses the pulmonary circulation. The ability of the pulmonary vasculature to filter air may be exceeded by a bolus injection of more than 30 ml air. Air embolism is suspected if acute neurological symptoms occur after inserting a central venous catheter. Echocardiography, especially transoesophageal echocardiography. Is highly sensitive in detecting air emboli in the ventricles. Treatment is effected with hyperbaric oxygen and standard measures of intensive-care medicine.     

Clinical evaluation of the Alta hip bolt in peritrochanteric hip fractures

We reviewed the clinical and radiographic results of 58 patients with peritrochanteric fractures treated with the Alta hip bolt (a sliding compression device that inserts a dome plunger in the femoral head instead of a hip screw). This group was compared with a group of 53 patients treated with conventional hip screws. Three patients (5.2%) treated with the Alta hip bolt and three patients (5.7%) treated with conventional hip screw had failure of fixation. Failure of fixation consistently occurred in patients with unstable fracture patterns or significant osteopenia. There were no cases of bolt cut-out in stable intertrochanteric fractures. We conclude that the Alta hip bolt performs as well as sliding hip screws in peritrochanteric fractures, but the additional learning curve and increased cost do not justify its routine use at this point in time.