The long term decline of a population of Avena fatua L., with different cultivations associated with spring barley cropping

The decline of a population of A. fatua established in September 1971, and not allowed to seed thereafter, was monitored in three successive barley crops Numbers of viable seeds in the son in June fell from 159 m² in 1972 to 1 m² in 1974 declining by 83° in the first, and by 96° in the second year. Seedling numbers fell from 138 m² in 1972 to 9 m² in 1974, declining by 32° in their first and by 89° in the second year. The slower decline of seedling numbers in the first year was attributed to loss of dormancy of seed reserves giving proportionally more seedlings in the second spring. Cultivations had no major influence on the pattern of seedling emergence in the spring, but they did affect population level. Where the stubble was cultivated immediately after seeding in September 1971, twice as many seedlings and three times as many seeds in the soil were present in 1972 compared with delayed autumn cultivations in 1971. From this greater reserve of seeds in the soil more seedlings arose in 1973 and in 1974. Time cultivation in the winter of 1971 resulted in slightly more seedlings in 1972 than did ploughing; this greater population declined more rapidly with line cultivation in 1973 and 1974. It is suggested that with no herbicidal control annual line cultivation will lead to a more rapid build up than ploughing: where A. fatua is controlled, the decline should be more rapid with tne cultivation. Persistence of A. fatua as a weed in arable situations seems related more to survivors shedding seeds than to the persistence of seeds on the soil. Factors which may influence the persistence of seeds in the soil are discussed.     

Biomechanical Comparison of Six Suture Configurations Using a Large Diameter Polyester Prosthesis in the Muscular Process of the Equine Arytenoid Cartilage

Objective— To compare biomechanical properties of 6 suture configurations using a large diameter polyester prosthesis in the muscular process (MP) of the arytenoid cartilage and to determine failure mode.
Study Design— Experimental study.
Sample Population— Cadaveric equine larynges (n=121).
Methods— Suture configurations (4 single, 2 double) were inserted, and then constructs were tested in a single-cycle to failure at a 100 mm/min distraction. Load deformation curves were generated to assess the biomechanical properties of each construct. A 1-way ANOVA was used to compare the mean differences in construct failure force, cricoarytenoid joint (CAJ) disarticulation force, and energy stored at failure. A 2-sample t-test was used to compare single versus double suture patterns and a Fisher's exact test was used to compare failure mode.
Results— Both construct and CAJ failure force were significantly greater ( P <.05) for double suture patterns compared with single suture patterns; however, there were no significant differences in energy stored at construct failure. Failure at the MP accounted for ≥50% of construct failures for 3 of the single suture patterns and 1 of the double suture patterns tested. The remaining 2 patterns had an increased frequency of clamp failures as well as failure of the cricoid cartilage.
Conclusions— Sutures that sufficiently engage the spine of the MP alone or in conjunction with a second suture were found to be biomechanically superior.
Clinical Relevance— Engaging the spine of the MP appears to result in the most biomechanically sound laryngeal construct.     

An Unusual Cause of Increasing Airway Pressure during Anesthesia

A mare with a thoracic laceration was anesthetized with halothane-O2 for surgical repair. Shortly after initiation of controlled ventilation, inspiratory plateau pressure began to increase. The increase in pressure continued despite decreasing the tidal volume. Tension pneumothorax was suspected, but because arterial PCO2 and PO2 were normal, the anesthetic apparatus was examined. Excess gas continued to exit through the bellows pop-off valve even when the fresh gas flow was turned off. It was determined that driving gas from the ventilator was entering the breathing circuit through a hole in the bellows. Testing the integrity of the bellows before use is suggested to avoid this potentially harmful complication.     

The Effects of Implant Orientation, Canal Fill, and Implant Fit on Femoral Strain Patterns and Implant Stability During Catastrophic Testing of a Canine Cementless Femoral Prosthesis

Cementless femoral stems were placed into 12 normal greyhound femora. The implanted femora were divided into three groups by stem orientation and implant size and loaded in axial compression at a rate of 25 newtons (N) per second until failure. Rosette strain gauges were used to measure femoral principal strains at 500 N, 1,000 N, 1,500 N, and at maximum load. During maximum load, varus orientation of the femoral stem had significantly higher tensile hoop strains in the proximomedial cortex, whereas neutral orientation had higher tensile hoop strains along the cranial cortex. Femoral fractures occurred in these areas of peak tensile strain. There was no difference in maximum load between groups, therefore varus orientation did not predispose to fracture. Maximizing canal fill and implant fit increased implant stability.     

Melaena associated with dexamethasone therapy in the dog

A retrospective study of seventeen cases of canine melaena incriminated a mean daily dosage of 3.6 mg/kg (range 1.3–13.8 mg/kg) of dexamethasone. All dogs were afflicted with some central nervous system disorder with intervertebral disc disease present in twelve of the cases. Ten of the the seventeen subjects had concurrently received ampicillin therapy. Causation was linked by the previous finding that ACTH and cortisone impede both gastric epithelial renewal and surface mucus formation.     

BIOLOG法测定土壤微生物群的一些局限性

Reduction of Cr(VI)to Cr(Ⅲ）were studied in a fresh wheat rhizosphere soil(Kuroboku,high humicandosol) pretreated with a basal fertilizer consisting of (NH4)2SO4,P2O5 and KH2PO4 and with K2Cr2O7 by using a rhizobox system.It was found that rhizosphere exerted a positive effect on Cr(VI) reduction.Part of the reason was the decrwease of pH in the rhizosphere due to application of (NH4)2SO4,implying that application of physiologically acid fertilizers would reduce Cr(VI) toxicity to plants.