Desistance From Childhood Aggression

This longitudinal study of disadvantaged boys (N = 258) had three aims. The first aim was to identify individuals who desisted from high early physical aggression (PA). A group-based trajectory analysis with different, age-sensitive measures of PA revealed that most aggressive young boys desisted (i.e., dropped to normative levels of PA) by middle childhood. Second, the study sought to discover predictors of desistance. In particular, analyses tested the proposition that desisters experience high child risk, low caregiving risk, and positive life transitions. The results provided partial support for this view. As anticipated, desisters were indistinguishable from chronically aggressive boys in PA and impulsivity at age 2. Contrary to expectation, however, desisters resembled boys with persistently low PA on a measure of fearfulness and exhibited intermediate risk (i.e., between chronics and lows) on toddlerhood measures of maternal depression, harsh parenting, and family adversity. Furthermore, life transition variables (e.g., changes in parenting, relationships with teachers and peers) failed to discriminate desisters from chronics or lows after accounting for early child and family factors. The third aim was to determine whether boys who desisted from early aggression experienced continuing difficulties in the form of social skills deficits or nonaggressive conduct problems. As expected, desisters improved in both domains according to maternal, teacher, and youth reports. In fact, by the end of middle childhood, desisters were indistinguishable from lows on these measures, with one exception: Mothers of desisters rated their sons higher on nonaggressive conduct problems

Sandia National Laboratories

Sandia National Laboratories has identified technology transfer to U.S. industry as a laboratory mission which complements our national security mission and as a key component of the Laboratory's future. A number of technology transfer mechanisms - such as CRADA's, licenses, work-for-others, and consortia - are identified and specific examples are given. Sandia's experience with the Specialty Metals Processing Consortium is highlighted with a focus on the elements which have made it successful. A brief discussion of Sandia's potential interactions with NASA under the Space Exploration Initiative was included as an example of laboratory-to-NASA technology transfer. Viewgraphs are provided

Simulation and performance of a high frequency cycloconverter

With modern naval vessels headed in the direction of integrated power systems, new attention must be paid to efficiency of both power and space. However, modern designs for ship power systems often incorporate DC link converters, or synchroconverters, into their design. Not only does this add extra steps into the power conversion process, it also adds the DC link, which requires large capacitors and can aggravate problems experienced in a short circuit. Modern research for cycloconverters is showing that they have many advantages over the synchroconverter when used in a ship power system. However, cycloconverters also have downsides. One of these problems is the incorporation of harmonics into the supply current, distorting the generator output, as well as voltage harmonics at the output of the converter, which can cause problems at the various loads. Most disastrous of all, additions of subharmonics, or interharmonics which occur below the fundamental can appear. Subharmonics are nearly unfilterable and they can cause serious problems for any power system. This study specifically considers higher frequency inputs to see if these subharmonics can be mitigated in a cycloconverter system.http://archive.org/details/simulationndperf109452773US Navy (USN) author.Approved for public release; distribution is unlimited

Titanacyclobutanes Derived from Strained, Cyclic Olefins: A New Living Polymerization System

Reaction of precursors of "Cp2Ti=CH2" (Cp = η5-C5H5) with cyclobutene yields polybutadiene. The preparation of the titanacyclobutane 3 by the addition of 3,3-dimethylcyclopropene to "Cp2Ti=CH2" is described. When phosphines PMeR2 (R = Me, Ph) are added to 3, phosphine adducts of the isomeric α-substituted titanium-carbene compound are obtained. Reaction with AlMe2Cl affords a heterobimetallic complex. Poly(dimethylpropenamer) is produced from reaction of 3 with excess olefin. The observed reactivity is consistent with productive cleavage of the metal-containing ring in 3 to "Cp2Ti=CHC(CH3)2CHCH2." Titanacyclobutanes 7 and 11 have been prepared from the reaction of norbornene with precursors of "Cp2Ti=CH2" and with metallacycle 3, respectively. On thermolysis, both 7 and 11 produce products consistent with the intermediacy of α-substituted titanocene-carbene compounds. Thermolysis at 65°C in the presence of excess norbornene affords ring-opened polynorbornene with a cis to trans ratio of 38:62. The polymerizations are highly efficient in catalyst and yield polymers of controlled molecular weight. Polymer prepared from 11 shows polydispersities as low as 1.07 based on gel permeation chromatography versus polystyrene standards. The molecular weight distributions of polymers obtained with 7 are always broader than those obtained with 11. The kinetics of both polymerizations are zero-order in monomer with ΔG‡338 = 24 kcal/mol, ΔH‡ = 27 kcal/mol, and ΔS‡ = 9 e.u. Polymerization with 7 shows an induction period corresponding to a first-order decay of 7 with t1/2 = 80 min at 65°C, whereas the polymerization with 11 is linear throughout. Simultaneous incorporation of d2-norbornene into the polymer by all active sites confirms that this system is best described as a living polymer. The polymerization mechanism is discussed as an olefin metathesis with rate-limiting cleavage of trisubstituted titanacyclobutanes affording high energy carbene intermediates. Reaction of endo-dicyclopentadiene with "Cp2Ti=CH2" and 3 affords titanacyclobutanes 15 and 16 with exclusive addition to the bicyclic double bond. The X-ray diffraction study of 15 indicates a puckered metal-containing ring. Polymerization of endo-dicyclopentadiene occurs with cleavage of the bicyclic ring system. Preliminary results demonstrate that cyclopentene can be polymerized with 3 at high monomer concentrations. The polymerization of norbornadiene to a linear ring-opened polymer is described. Reaction of these catalysts with 1,4-epoxy-1,4-dihydronapthalene occurs at the double bond and yields oligomers. Analysis of the microstructure of polymers prepared from methyl-norbornenes indicates that the double bonds in these polymers are predominantly trans. The catalysts exhibit a moderate head-to-tail selectivity. The preferred tacticity of dyads at trans double bonds is racemic while that at cis double bonds is meso.</p

Major Herbicides in Ground Water: Results from the National Water-Quality Assessment

To improve understanding of the factors affecting pesticide occurrence in ground water, patterns of detection were examined for selected herbicides, based primarily on results from the National Water-Quality Assessment (NAWQA) program. The NAWQA data were derived from 2227 sites (wells and springs) sampled in 20 major hydro- logic basins across the USA from 1993 to 1995. Results are presented for six high-use herbicides—atrazine (2-chloro-4-ethylamino-6-iso-propylamino- s-triazine), cyanazine (2-[4-chloro-6-ethylamino-1,3,5-triazin-2-yl]amino]-2-methylpropionitrile), simazine (2-chloro-4,6-bis- [ethylamino]-s-triazine), alachlor (2-chloro-N-[2,6-diethylphenyl]-N- [methoxymethyl]acetamide), acetochlor (2-chloro-N-[ethoxymethyl]- N-[ 2-ethyl-6-methylphenyl]acetamide), and metolachlor (2-chloro-N- [2-ethyl-6-methylphenyl]-N-[2-methoxy-1-methylethyl]acetamide)— as well as for prometon (2,4-bis[isopropylamino]-6-methoxy-s-triazine), a nonagricultural herbicide detected frequently during the study. Concentrations were \u3c1 μg L-1 at 98% of the sites with detections, but exceeded drinking-water criteria (for atrazine) at two sites. In urban areas, frequencies of detection (at or above 0.01 μg L-1 ) of atrazine, cyanazine, simazine, alachlor, and metolachlor in shallow ground water were positively correlated with their nonagricultural use nationwide (P \u3c 0.05). Among different agricultural areas, frequencies of detection were positively correlated with nearby agricultural use for atrazine, cyanazine, alachlor, and metolachlor, but not simazine. Multivariate analysis demonstrated that for these five herbicides, frequencies of detection beneath agricultural areas were positively correlated with their agricultural use and persistence in aerobic soil. Acetochlor, an agricultural herbicide first registered in 1994 for use in the USA, was detected in shallow ground water by 1995, consistent with previous field-scale studies indicating that some pesticides may be detected in ground water within 1 yr following application. The NAWQA results agreed closely with those from other multistate studies with similar designs

Surety of the nation`s critical infrastructures: The challenge restructuring poses to the telecommunications sector

The telecommunications sector plays a pivotal role in the system of increasingly connected and interdependent networks that make up national infrastructure. An assessment of the probable structure and function of the bit-moving industry in the twenty-first century must include issues associated with the surety of telecommunications. The term surety, as used here, means confidence in the acceptable behavior of a system in both intended and unintended circumstances. This paper outlines various engineering approaches to surety in systems, generally, and in the telecommunications infrastructure, specifically. It uses the experience and expectations of the telecommunications system of the US as an example of the global challenges. The paper examines the principal factors underlying the change to more distributed systems in this sector, assesses surety issues associated with these changes, and suggests several possible strategies for mitigation. It also studies the ramifications of what could happen if this sector became a target for those seeking to compromise a nation`s security and economic well being. Experts in this area generally agree that the U. S. telecommunications sector will eventually respond in a way that meets market demands for surety. Questions remain open, however, about confidence in the telecommunications sector and the nation`s infrastructure during unintended circumstances--such as those posed by information warfare or by cascading software failures. Resolution of these questions is complicated by the lack of clear accountability of the private and the public sectors for the surety of telecommunications

Statistical methods for assays with limits of detection: Serum bile acid as a differentiator between patients with normal colons, adenomas, and colorectal cancer

In analytic chemistry a detection limit (DL) is the lowest measurable amount of an analyte that can be distinguished from a blank; many biomedical measurement technologies exhibit this property. From a statistical perspective, these data present inferential challenges because instead of precise measures, one only has information that the value is somewhere between 0 and the DL (below detection limit, BDL). Substitution of BDL values, with 0 or the DL can lead to biased parameter estimates and a loss of statistical power. Statistical methods that make adjustments when dealing with these types of data, often called left-censored data, are available in many commercial statistical packages. Despite this availability, the use of these methods is still not widespread in biomedical literature. We have reviewed the statistical approaches of dealing with BDL values, and used simulations to examine the performance of the commonly used substitution methods and the most widely available statistical methods. We have illustrated these methods using a study undertaken at the Vanderbilt-Ingram Cancer Center, to examine the serum bile acid levels in patients with colorectal cancer and adenoma. We have found that the modern methods for BDL values identify disease-related differences that are often missed, with statistically naive approaches