Photoemission studies of high-tc superconductors: the superconducting gap

Over the last several years there have been great improvements in the energy resolution and detection efficiency of angle-resolved photoemission spectroscopy. These improvements have made it possible to discover a number of fascinating features in the electronic structure of the high transition temperature (T(c)) superconductors: apparently bandlike Fermi surfaces, flat-band saddle points, and nested Fermi surface sections. Recent work suggests that these features, previously thought explainable only by one-electron band theory, may be better understood with a many-body approach. Furthermore, other properties of the high-T(c) superconductors, which are difficult to understand with band theory, are well described using a many-body picture. Angle-resolved photoemission spectroscopy has also been used to investigate the nature of the superconducting pairing state, revealing an anisotropic gap consistent with a d-wave order parameter and fueling the current debate over s-wave versus d-wave superconductivity.     

Transition Element-Like Chemistry for Potassium Under Pressure

At high pressure the alkali metals potassium, rubidium, and cesium transform to metals that have a d1 electron configuration, becoming transition metal-like. As a result, compounds were shown to form between potassium and the transition metal nickel. These results demonstrate that the chemical behavior of the alkali metals under pressure is very different from that under ambient conditions, where alkali metals and transition metals do not react because of large differences in size and electronic structure. They also have significant implications for the hypothesis that potassium is incorporated into Earth's core.     

Positive Effects of Melatonin Treatment on the Reproductive Performance of Young Border Leicester Rams Mated to Merino Ewes in Spring: Preliminary Observations

Poor reproductive performance of Merino ewe flocks when mated to Border Leicester rams during spring may be due to seasonality of the Border Leicester breed. Two approaches were taken to test this assumption. Six young (12 months old) or six mixed‐age (12, 24 and ≥36 months old) Border Leicester rams were either treated or not treated with melatonin implants (2 × 2 design) 6 weeks before the four groups of rams were each put with approximately 300 Merino ewes for an 8‐week mating period. Implants were inserted in early September (experiment 1). The second approach was to yard or not yard ewes and mixed‐age rams on several occasions during the first 3 weeks of the mating period (experiment 2). Pregnancy rate and twinning percentage were assessed by ultrasonography. In experiment 1, melatonin treatment in young rams increased (p < 0.001) pregnancy rate from 5.0% to 92.6%, but mixed‐age rams did not respond (90.7% vs 89.5% for melatonin and non‐melatonin treatments, respectively). Twinning rate was similar (p > 0.05) for ewes mated to either melatonin or non‐melatonin‐treated young rams (36.8% vs 40.0%, respectively), whereas melatonin significantly improved (p < 0.05) twinning rate in those ewes mated to mixed‐age rams (49.1% vs 36.1%). After 6 weeks of melatonin treatment, scrotal circumference was greater (p < 0.05) in both young and mixed‐aged rams than in untreated counterparts. In experiment 2, yarding of ewes and rams overnight on several occasions early in the mating period reduced (p < 0.001) pregnancy rate compared with non‐yarded counterparts (89.5% vs 65.5%). Twinning rate was not affected (37.7% vs 36.1%, respectively). In summary, melatonin treatment of Border Leicester rams significantly improved flock reproductive performance in spring due to improved pregnancy rates with young rams and improved litter size with mixed‐age rams.     

Liposome-encapsulated oxymorphone provides prolonged relief of post-surgical visceral pain in rats

A delayed‐release formulation of liposome‐encapsulated oxymorphone was produced using a novel dehydration–rehydration technique. The purpose of this study was to (i) compare the analgesic properties of this preparation with those of repeated injections of standard oxymorphone in rats with post‐operative visceral pain and (ii) determine whether liposome‐encapsulated oxymorphone differed from standard oxymorphone in duration of the effect. Visceral pain was elicited in approximately 300 g Sprague–Dawley rats by intestinal resection performed under isoflurane anesthesia. Rats were monitored with pulse oximetry; mean anesthesia time (35 ± 10 minutes) did not differ between the groups. Rats were randomly divided into two groups: Group 1 received 1.2 mg kg^?1 liposome‐encapsulated oxymorphone SC once at skin closure and 0.2 mL of saline SC every 4 hours; Group 2 received 0.2 mL liposome‐encapsulated sucrose SC once at skin closure and 0.3 mg kg^?1 standard oxymorphone SC every 4 hours. In both groups, a behavioral ethogram for pain score (grooming, porphyrin staining, body position) was recorded every 4 hours for 48 hours after surgery. Observers were blinded to the treatment. Body weight, food consumption, and urine output were recorded daily for 7 days after anesthetic recovery. Data were analyzed using anova , with significance at p < 0.05. Based on the behavioral pain score, a single injection of liposome‐encapsulated oxymorphone was as effective for relief of post‐surgical visceral pain in rats as multiple (every 4 hours) injections of standard oxymorphone administered over a 48 hour period (p = 0.18). In rats, given one dose of liposome‐encapsulated oxymorphone, the mean body weight change from day 0 to day 7 was +9.4 g, whereas rats given multiple injections of standard oxymorphone had a mean body weight change of ?3.6 g over this time (p < 0.01). Mean daily food consumption was significantly less in rats given multiple injections of standard oxymorphone (p < 0.05). There was no difference between groups in urine production. In conclusion, a single dose of liposome‐encapsulated oxymorphone was effective in treating visceral pain in rats. Rats treated with liposome‐encapsulated oxymorphone had improved recovery, based on body weight changes and food consumption, compared with rats treated with multiple doses of standard oxymorphone. Liposome‐encapsulated oxymorphone offered advantages including provision of effective analgesia, prolonged dosing intervals, and minimal handling stress.     

Effect of dietary intake on concentrations of insulin-like growth factor-I in plasma and follicular fluid, and ovarian function in heifers.

The objective of this study was to determine if alterations in dietary intake of heifers can influence IGF-I concentrations in plasma and(or) follicular fluid (FFL), size of follicles, and steroid concentrations in FFL (as an indicator of steroidogenic capacity). Cyclic heifers [n = 23; mean +/- SE body weight (BW) = 373 +/- 7 kg] were individually fed for 10 weeks either: a) 1.8% of BW in dry matter (DM) per d (GAIN; n = 7), b) 1.1% of BW in DM per d (MAINT; n = 8) or c) 0.7% of BW in DM per d (LOSE; n = 8). After 10 wk of treatment, heifers were ovariectomized 36-40 hr after the second injection of prostaglandin F2 alpha analog (2 injections 11 d apart), and plasma and ovaries were collected. Heifers weighed 444 +/- 13,387 +/- 8 and 349 +/- 9 kg in the GAIN, MAINT and LOSE groups, respectively, at time of ovariectomy. Mean diameter of follicles greater than or equal to 10 mm was greater (P less than .05) for GAIN (15.6 mm) than for MAINT (11.0 mm) or LOSE (12.5 mm) heifers. Numbers of follicles and concentrations of IGF-I in plasma and FFL did not differ (P greater than .20) between LOSE, MAINT and GAIN heifers. Progesterone concentrations were greater (P less than .05) in small and medium follicles of GAIN than MAINT or LOSE heifers, but were unaffected by diet in large follicles. Estradiol concentrations in FFL in small, medium and large follicles were unaffected (P greater than .20) by dietary treatment.(ABSTRACT TRUNCATED AT 250 WORDS)     

An outbreak of toe ulcers,sole ulcers and white line disease in a group of dairy heifers immediately after calving

Abstract

CASE HISTORY: An outbreak of severe lameness was reported on a 780-cow spring-calving dairy herd in the Manawatu region within 1–3 weeks of calving, which affected over 90% of a group of 150 dairy heifers. Approximately 3 weeks before the planned start of calving heifers had been fed maize and grass silage on a concrete feed pad for 3–4 h per day, and mixed with a group of adult cows.

CLINICAL FINDINGS: During treatment for lameness, the feet of 28 lame heifers were closely examined. Seventy lesions were recorded in the claws of these heifers. The predominant lesion was severe solar and white line haemorrhage, with much of the haemorrhage focussed at the site at which sole ulcers are normally seen. White line disease was seen in nine claws and sole ulcers in four. Additionally, a lesion which is not commonly recorded in New Zealand, a toe abscess arising from separation of the white line from the sole in the abaxial region of tip of the toe was recorded in 11 claws. The clinical impression was that the soles of the affected heifers were very thin. This was supported by examination of the feet of eight heifers using ultrasonography that indicated heifers with hoof horn haemorrhages had very thin soles (estimated mean 4.1 mm) and that these soles were thinner than those in non-lame heifers without haemorrhages.

DIAGNOSIS: The pattern of disease seen in these heifers closely matched that seen in an outbreak of lameness in heifers in Florida, which was linked to thin soles resulting from excess hoof horn wear. The clinical signs and findings of the examination using ultrasonography strongly implicated thin soles as the underlying cause of lameness on this farm. An on-farm investigation revealed a combination of heifer behaviour and prolonged exposure to wet concrete on the feed pad were the primary causes of excess wear that resulted in thin soles.

CLINICAL RELEVANCE: This was an unusual outbreak of lameness in a group of newly calved heifers. The problem highlights the value of good management during the transition of heifers at pasture to the lactating herd standing on concrete for long periods, in the control of lameness.     

Effects of age-related increases in sapwood area,leaf area,and xylem conductivity on height-related hydraulic costs in two contrasting coniferous species

Introduction  

Knowledge of vertical variation in hydraulic parameters would improve our understanding of individual trunk functioning and likely have important implications for modeling water movement to the leaves. Specifically, understanding how foliage area (A _l), sapwood area (A _s), and hydraulic specific conductivity (k _s) vary with canopy position to affect leaf-specific conductivity (LSC) and whole-tree leaf-specific hydraulic conductance (K _l) may explain some of the contrasting patterns of A _l/A _s reported in the literature.     

Influence of body condition at calving and postpartum nutrition on endocrine function and reproductive performance of primiparous beef cows

The influences of body condition score (BCS) at calving and postpartum nutrition on endocrine and ovarian functions, and reproductive performance, were determined by randomly allocating thin (mean BCS = 4.4 +/- 0.1) or moderate condition (mean BCS = 5.1 +/- 0.1) Angus x Hereford primiparous cows to receive one of two nutritional treatments after calving. Cows were fed to gain either 0.45 kg/d (M, n = 17) or 0.90 kg/d (H, n = 17) for the first 71 +/- 3 d postpartum. All cows were then fed the M diet until 21 d after the first estrus. A replication (yr 2; M, n = 25; H, n = 23) was also used to evaluate reproductive characteristics. Concentrations of IGF-I, leptin, insulin, glucose, NEFA, and thyroxine were quantified in plasma samples collected weekly during treatment and during 7 wk before the first estrus. Estrous behavior was detected by radiotelemetry, and luteal activity was determined based on concentrations of progesterone in plasma. All cows were bred by AI between 14 and 20 h after onset of estrus, and pregnancy was assessed at 35 to 55 d after AI by ultrasonography. Cows that calved with a BCS of 4 or 5 had similar endocrine function and reproductive performance at the first estrus. During treatment, H cows gained BW and increased BCS (P < 0.01), and had greater (P < 0.05) concentrations of IGF-I, leptin, insulin, glucose, and thyroxine in plasma than M cows. However, during the 7 wk before the first estrus, plasma concentrations of IGF-I, leptin, insulin, glucose, NEFA, and thyroxine were not affected by time. Cows previously on the H treatment had a shorter (P < 0.01) interval to first postpartum estrus and ovulation, and a larger dominant follicle (P < 0.01) at first estrus, than M cows, but duration of estrus and the number of mounts received were not influenced by nutrient intake. Pregnancy rate at the first estrus was greater (P < 0.03) for H (76%, n = 38) than for M (58%, n = 33) cows. Increased nutrient intake after calving stimulated secretion of anabolic hormones, promoted fat deposition, shortened the postpartum interval to estrus, and increased pregnancy rate at the first estrus. Concentrations of IGF-I and leptin in plasma were constant during 7 wk before the first estrus, indicating that acute changes in these hormones are not associated with the resumption of ovarian function in primiparous beef cows.