Abrupt temperature changes in the Western Mediterranean over the past 250,000 years

A continuous high-resolution Western Mediterranean sea surface temperature (SST) alkenone record spanning the past 250,000 years shows that abrupt changes were more common at warming than at cooling. During marine isotope stage (MIS) 6, SST oscillated following a stadial-interstadial pattern but at lower intensities and rates of change than in the Dansgaard/Oeschger events of MIS 3. Some of the most prominent events occurred over MISs 5 and 7, after prolonged warm periods of high stability. Climate during the whole period was predominantly maintained in interglacial-interstadial conditions, whereas the duration of stadials was much shorter.     

Thermally Switchable Periodicities and Diffraction from Mesoscopically Ordered Materials

Two switchable, mesoscopically periodic materials were created by combining crystalline colloidal array (CCA) self-assembly with the temperature-induced volume phase transition of poly(N-isopropylacrylamide) (PNIPAM). Body-centered-cubic CCAs of hydrated, swollen PNIPAM particles Bragg-diffract infrared, visible, and ultraviolet light weakly, whereas arrays of compact shrunken particles diffract efficiently. A tunable diffracting array was also created by embedding a CCA of polystyrene spheres within a PNIPAM hydrogel that swells and contracts with temperature; thus the array lattice constant varies with temperature, and the diffracted wavelength was thermally tunable across the entire visible spectrum. These materials may find applications in many areas of optics and materials science.     

South american geochronology: radiometric time scale for middle to late tertiary mammal-bearing horizons in patagonia

Radiometric (potassium-argon) age determinations for basalts and tuffs associated with middle to late Tertiary mammal-bearing horizons in Patagonia, southern Argentina, permit refinement of boundaries and hiatuses between beds of Deseadan (early Oligocene) through Friasian (middle to late Miocene) age. At two localities beds of Deseadan age are overlain by basalts, which gave dates of 33.6 and 35.4 million years ago; 34.0 million years ago is tentatively accepted as a terminal date for known Deseadan. At several localities beds of Colhuehuapian age are underlain by basalts, which gave dates ranging from 28.8 to 24.3 million years ago; 25.0 million years is tentatively taken as a basal age for known Colhuehuapian. The paleontological hiatus between known Deseadan and known Colhuehuapian is thus in the order of 9.0 million years. Two tuffs from the Santa Cruz Formation (Santacrucian) gave ages of 21.7 and 18.5 million years. Plagioclase and biotite concentrates of an ignimbrite from the Collón Curá Formation (Friasian) gave ages ranging from 15.4 to 14.0 million years.     

Use of the Anemon Index to evaluate the quality of analgesia during fentanyl and sevoflurane anaesthesia in pigs

Anemon I is a new monitoring system that can be used to evaluate autonomic nervous system reactivity in real time by showing a simple, easily interpretated quantitative index (0–200), the Anemon Index (AI) ( Junke et al. 2000 ). This study used the AI to evaluate the quality of analgesia during sevoflurane and fentanyl anaesthesia in pigs. Six healthy pigs, weighing 24.76 ± 3.40 kg, were induced to anaesthesia with 5% sevoflurane (SEVO) in 5 L minute^?1 oxygen. After endotracheal intubation SEVO was given at 1 MAC (2.66%) in 3 L minute^?1 oxygen. Fentanyl was infused IV at 50 µg kg^?1 hour^?1 for the first 30 minutes of anaesthesia, discontinued for 30 minutes, and then infused at 100 µg kg^?1 hour^?1 for another 30 minutes. Three mechanical noxious stimuli (needle prick, pin‐prick and pressure on the abdomen) were applied for 15 seconds at 30, 60 and 90 minutes. The AI, ECG, invasive mean arterial blood pressure (MAP), heart rate (HR), SpO₂ by pulse oximetry, tidal volume, Fe′sevo , Fe ′CO₂ and respiratory rate were recorded before induction (baseline), after induction, after intubation and extubation, and before and during noxious stimulation at 30, 60 and 90 minutes. Recovery times were recorded. Statistically significant differences were determined by anova . Spearman rank‐correlation was used to evaluate the relationship between AI and hemodynamic variables. A p‐value of < 0.05 was considered significant. A significant (p < 0.01) decrease in AI was recorded after anaesthetic induction, from 82.3 ± 21.1 to 52.7 ± 20.3. After intubation, AI increased slightly, but not significantly, to 71.7 ± 27.1. A significant (p < 0.05) increase of AI occurred after extubation. Nociceptive stimuli did not have any measurable effect either on AI or on recorded cardiovascular variables. There was no movement, respiratory changes, or any other visible response to noxious stimulation. The AI did not change significantly with the different doses of fentanyl. Respiratory depression and apnoea were seen in all animals during the fentanyl infusion; therefore, pigs received intermittent positive pressure ventilation. Anaesthesia with sevoflurane and fentanyl resulted in a significant (p < 0.001) decrease in MAP. Heart rate did not change significantly. There was no correlation between AI and cardiovascular variables (HR and MAP). Endotracheal intubation caused an increase and extubation a greater significant increase in the AI. This suggests that intubation and extubation may represent stressful events during general anaesthesia, although further studies are needed to validate the use of the AI in pigs. Sevoflurane anesthetic induction may not prevent the sympathetic stimulus caused by endotracheal intubation in pigs, as indicated by the increased AI values.     

肉鸡的最适维生素E营养

<正>1肉鸡饲料中的维生素需要量1.1维生素之间及其与其它营养素的复杂相互作用维生素并非一种单独的营养素,不同维生素之间存在各种各样的相互作用。例如,脂溶性维生素互相竞争小肠吸收,其中一种维生素过量可能导致其它维生素缺乏,使用高水平的维生素A时表现尤     

美洲鳗白仔对三种饵料的选择性及消化率研究

报道了美洲鳗( Anguilla rostrata )白仔对水蚯蚓( Tubifex sp )、卤虫( Artem ia sp )和鱼卵三种饵料的选择性、消化率及摄食后的生长情况。试验结果表明,美洲鳗白仔对上述3 种饵料的选择性明显不同:水蚯蚓> 卤虫> 鱼卵。从其对3 种饵料的消化率及生长情况来看,水蚯蚓和卤虫对美洲鳗白仔的饲养效果较好,而鱼卵的饲养效果则较差。