Further Tests of the Influence of Black Mayors on Murders of Police: A Response to Jacobs

Author's manuscript made available in accordance with the publisher's policy.In response to our reanalysis and extension of Jacobs and Carmichael (2002) in which we found no evidence of a Black mayor effect, Jacobs (this issue) critiques our article on theoretical and methodological grounds. Theoretically, Jacobs argues that we did not provide sufficient justification for the inclusion of the percentage of the city council that was Black. Methodological criticisms include failure to include a nonlinear specification of percent divorced, improper temporal ordering, and the inclusion of only a single regional dummy variable. In our rejoinder we clarify the theoretical importance of the percentage of the city council that was Black and we address each of Jacobs’ methodological concerns. In additional analyses, we again find that the effect of the Black mayor variable is not robust to model specification or data employed, which was the point of our original article

Reassessing Political Explanations for Murders of Police

Author's manuscript made available in accordance with the publisher's policy.The article discusses how Jacobs and Carmichael, drawing on the racial threat thesis, argue that the overrepresentation of Blacks among felons who murder police is in part explained by Blacks' conscious or unconscious responses to political subordination by the State. In testing this argument, Jacobs and Carmichael find that their key theoretical variable—the presence of a Black mayor—is inversely related to police homicides and injurious assaults across many model specifications. This article describes a limited reanalysis of Jacobs and Carmichael's homicide data and additional analyses with a larger sample of cities. The findings suggest that the significance of the Black mayor variable may have been an artifact of model specification. Instead, there is evidence that Black city council representation may be associated with reduced homicides of police by Blacks. Further research is needed, however, because of the limited explanatory power of the key factors highlighted in past research

Laser Additive Manufacturing Process of a Mixture of Iron and Nickel Powders

Laser-based powder bed additive manufacturing (AM) of metal powders uses pre-alloyed powder, which limits the alloys available for processing. Other processes using metal powders such as powder metallurgy (PM) (press and sinter and MIM (Metal Injection Molding)) and welding use elemental powder mixtures to produce a wide variety of alloy compositions. This study tests the ability of laser AM to produce a homogeneous alloy from a mixture of powders.Mechanical Engineerin

EXAFS study of nickel tetracarbonyl and nickel clusters in zeolite Y

Adsorption and thermal decomposition of Ni(CO)4 in the cage system of zeolite Y have been studied with EXAFS, electron microscopy and IR spectroscopy , Ni(CO)4 is adsorbed as an intact molecule in both cation - free zeolite Y and NaY. Symmetry changes of the molecule in NaY are assigned to the formation of Na—OC-IMi bridges. Thermal treatment of the Ni(CO)4/NaY adduct leads to loss of CO concomitant with the formation of a binodal Ni phase. A major part of the forms clusters with diameter between 0.5 and about 1.5 nm, in addition to larger crystallites (5-30 nm), sticking at the outer surface of the zeolite matrix., The Ni-Ni scattering amplitude indicates increasing average particle size with increasing temperature

Alcohol outlets, social disorganization, and non-violent crimes in urban neighborhoods

Many studies show an association between alcohol outlets and violence, though fewer consider non-violent crime. We add to this literature using block group data from Milwaukee, Wisconsin, to explore whether (1) on- and off-premise alcohol outlet density is related to thefts from vehicles and vandalism and (2) social disorganization moderates these associations. Using spatially informed regression models, we found positive effects of on-premise alcohol outlet density on thefts from vehicles. We also found positive effects of on- and off-premise alcohol outlet density on vandalism. Social disorganization was not a consistent moderator of these associations

Spin dynamics in electrochemically charged CdSe quantum dots

We use time-resolved Faraday rotation to measure coherent spin dynamics in colloidal CdSe quantum dots charged in an electrochemical cell at room temperature. Filling of the 1Se electron level is demonstrated by the bleaching of the 1Se-1S3/2 absorption peak. One of the two Lande g-factors observed in uncharged quantum dots disappears upon filling of the 1Se electron state. The transverse spin coherence time, which is over 1 ns and is limited by inhomogeneous dephasing, also appears to increase with charging voltage. The amplitude of the spin precession signal peaks near the half-filling potential. Its evolution at charging potentials without any observable bleaching of the 1Se-1S3/2 transition suggests that the spin dynamics are influenced by low-energy surface states.Comment: 4 pages, 4 figure

Aroma qualities of raw hops and hops in beer by trained panel free-choice profiling

Hops contribute many desirable aromas to beer. Traditionally hop aromas have been described by the point of addition in the brewing process (dry-hop, finish-hop, or kettle-hop). The compounds present in the oil provide a wide range of aroma qualities. Since the composition of the oil is different for each hop variety it is reasonable to assume that the aroma qualities of each variety would be different. Moreover, since a different composition of compounds would be added to the beer at each addition point, it would be expected that different hop varieties would produce beers with different aroma qualities. Trained panel free-choice profiling was used to evaluate the aroma qualities of selected raw hops and of dry-hopped lagers and finish-hopped lagers produced with the same hops. The first study compared the aroma qualities of eight commercial and seven experimental varieties of raw hops. The raw hops had intense aromas and were separated into five different groups based on their aroma qualities. Three experimental varieties were found to have similar aroma qualities to varieties with German parentage. There was a strong correlation between the concentration of the hop oil compounds and the aroma qualities that separated the varieties. The second and third studies compared the aroma qualities of American Lagers dry-hopped (second) and finish-hopped (third) with twelve of the fifteen hop varieties from the first study. In both studies the lagers were separated into three groups based on their aroma qualities. There was no relationship that could be applied to all varieties between the aroma qualities of the dry-hopped lagers and the finish-hopped lagers. Comparing the aroma qualities of the hop varieties from all three studies, the aroma qualities of many of the raw hops were similar when used for dry-hopping, but changed when used for finish-hopping. Hallertauer Tradition and Spalter Select had fruity and floral qualities in all studies. Experimental variety 21683 had similar aroma qualities to Hallertauer Gold in all three studies

Natural gas cost for evaluating energy resource opportunities at Fort Stewart

Ft. Stewart, a United States Army Forces Command (FORSCOM) installation located near Hinesville, Georgia, is currently undergoing an evaluation of its energy usage, which is being performed by Pacific Northwest Laboratory. In order to examine the energy resource opportunities (EROs) at Ft. Stewart, marginal fuel costs must be calculated. The marginal, or avoided, cost of gas service is used in conjunction with the estimated energy savings of an ERO to calculate the dollar value of those savings. In the case of natural gas, the costing becomes more complicated due to the installation of a propane-air mixing station. The propane-air station is being built under a shared energy savings (SES) contract. The building of a propane-air station allows Ft. Stewart to purchase natural gas from their local utility at an interruptible rate, which is lower than the rate for contracting natural gas on a firm basis. The propane-air station will also provide Ft. Stewart with fuel in the event that the natural gas supply is curtailed. While the propane-air station does not affect the actual cost of natural gas, it does affect the cost of services provided by gas. Because the propane-air station and the SES contract affect the cost of gas service, they must be included in the analysis. Our analysis indicates a marginal cost of gas service of 30.0 cents per therm, assuming a total propane usage by the mixing station of 42,278 gallons (38,600 therms) annually. Because the amount of propane that may be required in the event of a curtailment is small relative to the total service requirement, variations in the actual amount should not significantly affect the cost per therm

Energy saving potential of residential HVAC options at Fort Irwin, California

The Pacific Northwest Laboratory (PNL) evaluated heating and cooling system options for existing family housing at Fort Irwin, California. The purpose of this work was to quantify the energy conservation potential of alternative system types and to identify the most cost-effective technology available. The conventional residential heating/cooling systems at Fort Irwin are separate propane forced-air furnaces and central air conditioners. The options examined included air- and ground-source heat pumps, a natural gas furnace with central air conditioning, and a natural-gas-fired heat pump. The most cost-effective technology applicable to Fort Irwin was found to be the high-efficiency ground-source heat pumps. If all conventional units were replaced immediately, the net energy savings would be 76,660 MBtu (80.9 TJ) per year and a reduction in electrical demand of approximately 15,000 kW-month. The initial investment for implementing this technology would be approximately $7.1 million, with a savings-to-investment ratio of 1.74