Indexes of skewness and kurtosis for a test-score distribution are expressed in terms of item parameters. Both are shown to depend, in part, on item means, variances, and covariances. The index of skewness depends also on trivariances. A trivariance is a product moment involving first powers of deviation scores for three items. The index of kurtosis depends on quadrivariances, as well as trivariances. A quadrivariance is a product moment involving first powers of deviation scores for four items. Empirical data are presented for responses of groups of subjects to 25 triads and 25 tetrads of items from five tests.

We present a re-discovery of G278.94+1.35a as possibly one of the largest known Galactic supernova remnants (SNRs) – that we name Diprotodon. While previously established as a Galactic SNR, Diprotodon is visible in our new Evolutionary Map of the Universe (EMU) and GaLactic and Extragalactic All-sky MWA (GLEAM) radio continuum images at an angular size of $3{{{{.\!^\circ}}}}33\times3{{{{.\!^\circ}}}}23$, much larger than previously measured. At the previously suggested distance of 2.7 kpc, this implies a diameter of 157$\times$152 pc. This size would qualify Diprotodon as the largest known SNR and pushes our estimates of SNR sizes to the upper limits. We investigate the environment in which the SNR is located and examine various scenarios that might explain such a large and relatively bright SNR appearance. We find that Diprotodon is most likely at a much closer distance of $\sim$1 kpc, implying its diameter is 58$\times$56 pc and it is in the radiative evolutionary phase. We also present a new Fermi-LAT data analysis that confirms the angular extent of the SNR in gamma rays. The origin of the high-energy emission remains somewhat puzzling, and the scenarios we explore reveal new puzzles, given this unexpected and unique observation of a seemingly evolved SNR having a hard GeV spectrum with no breaks. We explore both leptonic and hadronic scenarios, as well as the possibility that the high-energy emission arises from the leftover particle population of a historic pulsar wind nebula.

Ethnohistoric accounts indicate that the people of Australia's Channel Country engaged in activities rarely recorded elsewhere on the continent, including food storage, aquaculture and possible cultivation, yet there has been little archaeological fieldwork to verify these accounts. Here, the authors report on a collaborative research project initiated by the Mithaka people addressing this lack of archaeological investigation. The results show that Mithaka Country has a substantial and diverse archaeological record, including numerous large stone quarries, multiple ritual structures and substantial dwellings. Our archaeological research revealed unknown aspects, such as the scale of Mithaka quarrying, which could stimulate re-evaluation of Aboriginal socio-economic systems in parts of ancient Australia.

Extension workers often identify production, marketing, managerial, or educational constraints that reduce agricultural efficiencies. The preceding papers documented that both yellow and purple nutsedge (Cyperus esculentus L. # CYPES and C. rotundus L. # CYPRO) are serious weeds in many worldwide agricultural cropping systems. Detailed literature reviews and suggested directions for future research also were presented. As a partial summary of the symposium, this paper attempts to condense the information regarding yellow nutsedge into several options or strategies for consideration by year-round weed management practitioners.

In the 1990s, citizens regard green lawns and golf courses with attitudes ranging from pleasure for their beauty to dismay caused by concerns for environmental consequences. Citizens concerned with environmental consequences describe fertilizers or pesticides that may be harmful to groundwater or other organisms while others worry about the harm caused by more bee stings or economic and aesthetic losses caused by unsightly weeds. Both sides of an issue can be supported by facts. The listener may have difficulty forming an opinion since many issues do not have a clearly right or wrong approach. How should educators deal with this sort of dilemma? Are learning methods available to explore people's values, data, assumptions, and practices?

Organizer's comments: Systems inquiry represents an array of research-based problem-solving approaches. European experience with the pesticide debate suggests several simple messages contained in this paper. As weed scientists, we have everything to gain by considering a global sphere of views, practices, logic, experience, and message. Read this paper for the essence, the message, the systems thinking, the research framework, and the interface between society and weed science. Read it because science and society must communicate.

The effects of seed depth on growing point location of wild-proso millet, effects of alachlor placement, and chemical control of wild-proso millet were studied in field and greenhouse experiments. In 1986, 55 to 88% of the seedlings originating in the top 6 cm of soil had their growing point above the soil surface. The respective figures were 11 to 36% in 1987. Shoot exposure to alachlor resulted in significantly greater phytotoxicity than root exposure. Only EPTC or vernolate with a protectant, preplant incorporated, or pendimethalin preemergence, followed by atrazine plus tridiphane postemergence controlled wild-proso millet more than 85% all season.

Basic, applied, operational, and human activity research systems represent an array of inquiry methodologies. Techniques or methods within each methodology exhibit similar functions, although purposes and results of each inquiry process differ. Appreciation and possible use of the entire inquiry process focuses attention on scale questions within a hierarchy, and encourages use of all methodologies to enhance resolution of diverse situations. Systems inquiry recognizes the need for weed scientists and agriculturists to participate in activities ranging between reductionist science and human action research.

Historically, many herbicides have been tested for control of purple and yellow nutsedge, (Cyperus rotundus L. # CYPRO and (C. esculentus L. # CYPES). However, most chemicals provide only poor or temporary control. Reasons for failure include marginal translocation of herbicides to sites of action, temporary inhibition of tuber sprouting, and control of new tuber formation or inconsistent control when applied at different stages of growth and under various environmental conditions. Evaluation criteria that emphasize control of new plants and foliage rather than inhibition of tuber sprouting or new tuber production also contribute to erratic results. Progress toward solving these research problems is evident in studies of the influence of herbicides relative to nutsedge growth stages, new tuber development, and tuber recovery following treatment. In this review, nutsedge response to herbicides grouped by their mode of action within plants will be summarized.

The effect of planting system and cover crop residues on weed emergence in irrigated vegetable row crops was studied in field experiments from 1995 through 1997. Vegetable crops were either no-till planted (NTP) through cover crop residues or conventionally planted (CP) into soil with cover crop residues incorporated. NTP reduced emergence of hairy nightshade by 77 to 99% and Powell amaranth emergence by 50 to 87% compared with CP. Cover crop treatments were much less important than planting system in regulating weed emergence. Tillage in the spring did not increase the number of viable seeds near the soil surface. Hairy nightshade emergence ranged from 0.6 to 9.8% of the intact seeds in CP compared with 0 to 0.1% emergence of the seeds in the NTP plots. Powell amaranth emergence ranged from 4.9 to 6.5% of the intact seeds in CP contrasted with only 0.4 to 0.9% emergence of the seeds in NTP plots.

The effects of spring tillage sequence on summer annual weed populations were evaluated over two cycles of a 3-yr crop rotation of snap beans, sweet corn, and winter wheat. Continuous no-till (N) planting of vegetable crops each spring (NNNN) reduced summer annual weed density 63 to 86% compared to that of continuous conventional tillage (CCCC), depending upon site and herbicide level. Hairy nightshade populations were reduced by 88 to 96% when spring tillage was eliminated from the crop rotation. The effects of the NNNN spring tillage sequence on weed density were similar at two sites even though the crop rotations at the two sites began with different crops. The rotational tillage sequence of NCNC at the East site, in a crop rotation that began with corn, reduced summer annual weed density by 46 to 51% compared to that of continuous conventional tillage and planting (CCCC) at low and medium herbicide rates, respectively. In contrast, the tillage sequence of CNCN in the same crop rotation and at the same site increased weed density by 80% compared to that of CCCC at a low herbicide rate. The effects of the NCNC and CNCN rotational tillage sequences on weed density were reversed at the West site, and was probably caused by pairing sweet corn with conventional tillage rather than no tillage. The reduction in summer annual weed density caused by reduced spring tillage frequency did not significantly increase crop yields.

Reports of bloodstream infections caused by methicillin-resistant Staphylococcus aureus among chronic hemodialysis patients to 2 Centers for Disease Control and Prevention surveillance systems (National Healthcare Safety Network Dialysis Event and Emerging Infections Program) were compared to evaluate completeness of reporting. Many methicillin-resistant S. aureus bloodstream infections identified in hospitals were not reported to National Healthcare Safety Network Dialysis Event.

Infect. Control Hosp. Epidemiol. 2016;37(2):205–207

J. David Singer, a globally recognized scholar of international politics, died Monday, December 28, 2009, in Ann Arbor, Michigan. He was involved in an auto accident on September 22 and had been hospitalized since. At the time of his death, Singer was Professor Emeritus at the University of Michigan, where he'd been on the faculty from 1958 until retiring in 2002. He was 84 years old.

The series of papers on climate change published in this issue are the result of the symposium “Environmental Change in Mesoamerica: Physical Forces and Cultural Paradigms in the Preclassic to Postclassic,” held at the 63rd Annual Meeting of the Society for American Archaeology in March 2000 in Philadelphia. The authors bring their expertise in paleoclimatological studies to bear on the Maya Lowlands and Highlands from the beginning of the Holocene to the Postclassic and modern times. The studies reveal that climate has changed during the past 4,000 years to a considerable degree that correlates in a reasonable way with archaeological periodizations. Several climate-change models are presented as an effort to understand better past cultural and natural events.

We present early results from the analysis of HST imaging observations for several pairs of interacting galaxies. We include two cases that were specifically chosen to represent a strong early (young) encounter and a weak late (old) encounter. The goals of the project include a determination of the timing, frequency, strength, and characteristics of the young star clusters formed in these two limiting cases of tidal encounters.

Scanning tunneling microscopy images are reported for the wurtzite GaN(0001) surface. Terraces are observed, with three kinds of defect structures that are assigned to ordered N-vacancies: (i) striations perpendicular to the step edges, (ii) row defects spaced about 16 Å that intersect the steps at an angle of 30°, and (iii) “oval” defects that result from intersections of lines of vacancies (oriented at 60° with respect to step edges) with the row defects.