Ontogenetic data and the evolutionary origin of the mammalian scapula

One of the most useful diagnostic therian features is the division of the lateral surface of the scapula into two fossae separated by a scapular spine. A new model to describe this evolutionary innovation based on ontogenetic data is provided, consistent with information provided by recent fossil discoveries. The development of the scapula in three didelphid and one dasyurid marsupials using histological sections was studied. Only the ventral, acromial portion of the scapular spine, which originates from the anterior margin of the scapular blade, is preformed in cartilage. The major dorsal portion is formed at a later stage by appositional bone, which expands from the perichondral ossification of the scapula into an intermuscular aponeurosis between the supra-and infraspinatus muscles. This intermuscular aponeurosis inserts more or less in the middle of the lateral surface of the developing scapula. Thus, the floor of the supraspinous fossa is already present at the beginning of scapular development, simultaneous with the infraspinous fossa. The portion of the scapular spine that is situated dorsal to the acromial process is hypothesized to be a neomorphic structure of therians. The dorsal portion of the scapular spine evolved as additional attachment for powerful supraspinatus and infraspinatus muscles meeting near the middle of the lateral scapula.     

Comparison of first-trimester transvaginal amniocentesis with chorionic villus sampling and mid-trimester amniocentesis

Between August 1989 and December 1991, 356 patients underwent first-trimester transvaginal amniocentesis (10–12 weeks). The same number of patients referred in the same period for mid-trimester amniocentesis (14–21 weeks) was matched also for maternal age and indication. A third group consisted of the first 356 cases in which chorionic villus sampling (CVS) was attempted. The overall success rate was 99·7 and 100 per cent for early and mid-trimester amniocentesis, respectively, and 97·2 per cent for CVS. The mean harvesting time was 12·8, 11, and 7·9 days, respectively. The percentage of patients rescheduled was 3·4 per cent in first-trimester amniocentesis, 1·7 per cent in mid-trimester amniocentesis, and 6·2 per cent in the CVS group. The early (less than 2 weeks) pregnancy loss was 1·7 and 0·6 per cent in early and mid-trimester amniocentesis, respectively, and 1·7 per cent in CVS. The total pregnancy loss was 3·2, 0·9, and 2·9 per cent, respectively. The rate of preterm birth was 6·0, 5·2 and 6·9 per cent, respectively. The results indicate that CVS has the shortest procedure-result interval, but the highest rescheduling rate. First-trimester amniocentesis has a higher procedure and laboratory success rate but, until otherwise proved, mid-trimester amniocentesis is the most efficient and safest procedure.     

Introduction,dispersal and potential impacts of the green crab Carcinus maenas in San Francisco Bay,California

The North Atlantic portunid crab Carcinus maenas (Linnaeus, 1758) has invaded the North Pacific Ocean following more than two centuries of global dispersal due to human activities. C. maenas was first collected in San Francisco Bay, California, in 1989–1990, where its distribution and prey selectivity were investigated in 1992–1994. It has become abundant in shallow, warm lagoons (which as favorable and retentive microhabitats may have served as invasion incubators) and spread throughout the north, central and south bays. It may have arrived in ballast water, on fouled ships, amongst algae with imported live bait or lobsters, or by intentional release; genetic comparisons of the Bay population with possible source populations may aid in defining the transport mechanism. C. maenas' eurytopic nature, its high breeding potential, and its diet and feeding behavior suggest the potential for extensive ecosystem alterations through predator-prey interactions, competition, disturbance, and indirect effects. Although both negative economic impacts through reduction or disruption of fisheries and positive impacts of providing bait and human-food fisheries have been documented in a few regions, the potential economic impacts in San Francisco Bay remain largely unknown.     

Evaluating peats for their capacities to remove odorous compounds from liquid swine manure using headspace "solid-phase microextraction".

This paper reports on research designed to investigate the capacities of different highly characterized peats to remove odorous compounds from liquid swine manure (LSM). Peat types representing a wide range of properties were tested in order to establish which chemical and physical properties might be most indicative of their capacities to remediate odors produced by LSM. Eight percent slurries (of peat/LSM) were measured for odor changes after 24 hours using odor panel and GC/MS-Solid-phase microextraction (GC/MS-SPME) analysis. The GC/MS-SPME and odor panel results indicated that, although all peats tested in this study were found to be effective at removing odor-causing compounds found in LSM, some peats tended to work better than others. Overall, the peats that were the most effective at removing odor-causing compounds tended to have lower bulk densities, ash contents, fulvic acids contents, and guaiacyl lignins contents, and higher water holding capacities, hydraulic conductivities, "total other lignins" contents, hydrogen contents, carbon contents, and total cellulose contents. GC/MS-SPME analysis was found to be a reasonably inexpensive and efficient way of conducting this type of research. It allows one to identify a large number of the odor-causing compounds found in LSM, and more importantly, to detect with some precision specific differences in the amounts of these compounds between peat types.     

Preparing to measure the effects of the NOx SIP call--methods for ambient air monitoring of NO,NO2, NOy,and individual NOz species

The capping of stationary source emissions of NOx in 22 states and the District of Columbia is federally mandated by the NOx SIP Call legislation with the intended purpose of reducing downwind O3 concentrations. Monitors for NO, NO2, and the reactive oxides of nitrogen into which these two compounds are converted will record data to evaluate air quality model (AQM) predictions. Guidelines for testing these models indicate the need for semicontinuous measurements as close to real time as possible but no less frequently than once per hour. The measurement uncertainty required for AQM testing must be less than +/-20% (+/-10% for NO2) at mixing ratios of 1 ppbv and higher for NO, individual NOz component compounds, and NOy. This article is a review and discussion of different monitoring methods, some currently used in research and others used for routine monitoring. The performance of these methods is compared with the monitoring guidelines. Recommendations for advancing speciated and total NOy monitoring technology and a listing of demonstrated monitoring approaches are also presented.     

Alternative herbicides to manage Italian ryegrass (Lolium multiflorum lam) resistant to glyphosate at different phenological stages

During the growing season of 2002--2003, field and greenhouse experiments were conducted with the objective of evaluating the influence of Italian ryegrass phenological stages and management alternatives on the control of resistant biotypes to glyphosate. Three field experiments were conducted in Lagoa Vermelha, RS, Brazil and glyphosate was applied alone and in combinations with alternative herbicides. Two greenhouse experiments were also conducted at the Department of Crop Science, ESALQ/USP, Piracicaba, SP, Brazil. The Italian ryegrass resistant population was collected from Lagoa Vermelha, RS, Brazil. From the results it was possible to conclude that: (i) the more advanced the phenological stage of application, the more difficult the control of resistant Italian ryegrass by glyphosate, mainly by the rate of 960 g a.i. ha(-1); however, this rate applied at earlier phenological stage (five tillers), the control was higher than 90%; (ii) with the increment of glyphosate rate, it significant response was observed on the control at all stages of application; (iii) the mixture of glyphosate + clethodim (1440 + 72 g a.i. ha(-1)), paraquat + diuron (500 + 250 g a.i. ha(-1)), at all stages of application and clethodim (96 g a.i. ha(-1)) and paraquat + diuron (300 + 150 g a.i. ha(-1)) at the initial stages until pre-flowering were excellent alternatives for management of these populations; and (iv) the response of control was much faster for the mixture of glyphosate + clethodim, independently of growth stage.     

Effects of herbicide and insecticide interaction on soil entomofauna under maize crop

The aim of this study was to evaluate the impact of the herbicide mixture nicosulfuron + atrazine, with or without the insecticide chlorpyrifos, onto soil entomofauna under maize crop. The treatments, applied 25 days after maize emergence, were represented by a weeded control without insecticide and herbicide, a weeded control with chlorpyrifos, and mixtures of nicosulfuron + atrazine, with or without chlorpyrifos. Arthropods populations, on the soil surface, as well as inside the soil under maize, were principally represented by mites (Arachnida: Acari), decomposer collembolans (Hexapoda:Parainsecta:Collembola) and predator ants (Hymenoptera:Formicidae). The nicosulfuron + atrazine mixture with chlorpyrifos and the isolated chlorpyrifos reduced the population dynamics of all insect groups on the soil surface compared to the weeded control. In the soil, mite and ant populations were reduced after application of the herbicide mixture with chlorpyrifos and of the isolated chlorpyrifos.     

The stability of trophic mass-balance models of marine ecosystems: a comparative analysis

Dynamic simulations of 18

Full-size image

mass-balance marine trophic models are used to explore the stability of systems when briefly impacted by a fishery on the key ‘wasp–waist' populations occurring at intermediate trophic levels. The results are related to different ecosystem goal functions previously identified as representative of three attributes of ecosystems development: community complexity, homeostasis and energetics. System recovery time, the time required for all functional groups to returns to baseline level, and here used as a measure of model stability, was inversely correlated to Finn's Cycling Index, i.e. to the fraction of ecosystem throughput that is recycled, and to the mean length of trophic pathways in the systems. Systems with higher capacity to recycle detritus are systems with a higher ability to recover from perturbations. The results are in agreement with the E.P. Odum's theory of ecosystem development, where recycling is interpreted as a chief positive feedback mechanism that contributes to stability in the mature systems by preventing overshoots and destructive oscillations due to external impacts.