Mineralogy and petrology of comet 81P/Wild 2 nucleus samples

The bulk of the comet 81P/Wild 2 (hereafter Wild 2) samples returned to Earth by the Stardust spacecraft appear to be weakly constructed mixtures of nanometer-scale grains, with occasional much larger (over 1 micrometer) ferromagnesian silicates, Fe-Ni sulfides, Fe-Ni metal, and accessory phases. The very wide range of olivine and low-Ca pyroxene compositions in comet Wild 2 requires a wide range of formation conditions, probably reflecting very different formation locations in the protoplanetary disk. The restricted compositional ranges of Fe-Ni sulfides, the wide range for silicates, and the absence of hydrous phases indicate that comet Wild 2 experienced little or no aqueous alteration. Less abundant Wild 2 materials include a refractory particle, whose presence appears to require radial transport in the early protoplanetary disk.     

Chronology for the Aegean Late Bronze Age 1700-1400 B.C

Radiocarbon (carbon-14) data from the Aegean Bronze Age 1700-1400 B.C. show that the Santorini (Thera) eruption must have occurred in the late 17th century B.C. By using carbon-14 dates from the surrounding region, cultural phases, and Bayesian statistical analysis, we established a chronology for the initial Aegean Late Bronze Age cultural phases (Late Minoan IA, IB, and II). This chronology contrasts with conventional archaeological dates and cultural synthesis: stretching out the Late Minoan IA, IB, and II phases by approximately 100 years and requiring reassessment of standard interpretations of associations between the Egyptian and Near Eastern historical dates and phases and those in the Aegean and Cyprus in the mid-second millennium B.C.     

干旱胁迫下辣椒幼苗光合与荧光参数测定的最佳叶片

为明确干旱胁迫下不同叶位光合、荧光特性的变化规律,进而选择出典型叶片来准确测量干旱条件下植株光合、荧光参数,以实现干旱条件下植株光合能力的快速评价。研究通过盆栽试验对不同干旱处理下（充分供水（CK）：75%~85%田间持水量;中度胁迫（MS）：65%~75%田间持水量;重度胁迫（SS）:55%~65%田间持水量）辣椒幼苗不同叶位叶片的光合、荧光特性进行比较分析。结果表明：充分供水时,随叶位的增加,气体交换参数(净光合速率、气孔导度、蒸腾速率)、叶绿素含量、叶面积、叶绿素荧光参数(光化学淬灭系数、光系统Ⅱ最大光化学量子产量)均呈先增大后减小的趋势,在第3叶位达到最大值;在干旱条件时,各叶位的参数随水分胁迫程度的增加在1~3叶位逐渐减小,4~6叶位先增加后减小,并在第4叶位达到最大值(C_i、F₀、F_v/F_m、NPQ除外);水分胁迫对辣椒叶片光合作用影响较大,MS与SS处理,第3叶位的P_n分别较CK下降14.05%和55.91%,第4叶位的P_n MS处理较CK增加25.20%,SS处理较CK降低15.42%;第3、4叶位是对辣椒幼苗生长具有主要贡献的叶片,但在水分胁迫条件下,第3叶位光合参数、叶面积、叶绿素含量及叶绿素荧光参数的变异系数较第4叶位更大,尤其对于C_i、Chlb、F₀,在光合参数、叶绿素参数及叶绿素荧光参数中变幅最大,其第3叶位的变异系数分别较第4叶位增大了133.33%,180.00%及200.00%。第3叶位对于水分胁迫更加敏感,因此,在干旱胁迫实验中,宜选用第3叶位测量辣椒幼苗光合、荧光参数。     

Impact of co-infection with Lepeophtheirus salmonis and Moritella viscosa on inflammatory and immune responses of Atlantic salmon (Salmo salar)

This study was conducted to determine the effects of a co-infection with Moritella viscosa at different exposure levels of sea lice Lepeophtheirus salmonis in Atlantic salmon (Salmo salar). M. viscosa (1.14 × 10⁶ cfu/ml) was introduced to all experimental tanks at 10 days post-lice infection (dpLs). Mean lice counts decreased over time in both the medium lice co-infection (31.5 ± 19.0 at 7 dpLs; 16.9 ± 9.3 at 46 dpLs) and high lice co-infection (62.0 ± 10.8 at 7 dpLs; 37.6 ± 11.3 at 46 dpLs). There were significantly higher mortalities and more severe skin lesions in the high lice co-infected group compared to medium lice co-infected group or M. viscosa-only infection. Quantitative gene expression analysis detected a significant upregulation of genes in skin from the high lice co-infection group consistent with severe inflammation (il-8, mmp-9, hep, saa). Skin lesions retrieved throughout the study were positive for M. viscosa growth, but these were rarely located in regions associated with lice. These results suggest that while M. viscosa infection itself may induce skin lesion development in salmon, co-infection with high numbers of lice can enhance this impact and significantly reduce the ability of these lesions to resolve, resulting in increased mortality.     

The effects of drought on the water use, fruit development and oil yield from young olive trees

In Marlborough, New Zealand, olives are becoming an important crop alongside grapes. However, despite olives being drought resistant, they are generally planted on the poorer free-draining soils. Also, with the strong increase in cropping area, the demand for irrigation water has increased dramatically. In this research, we investigate the impact of short-term water stress on plant physiological processes, crop yield and oil quality in Marlborough, New Zealand. For that purpose, during the dry summer of 2000–2001, two trees were kept without irrigation for 64 days while two neighbouring trees were irrigated following standard practice. The trees were measured for transpiration (E), leaf and stem water potential (Ψ_L and Ψ_S), every other day, from dawn to dusk for three weeks from just before irrigation was started up again. All four trees were wired up for measuring stem sap flow (T) which was recorded hourly and a basic meteorological station provided weather data. Fruit and shoot development was measured weekly. It was found that under the short period of dry conditions with soil moisture (() dropping to <5%, olive trees kept functioning at a very low level with Ψ_L and Ψ_S reduced from −1 to <−4.0 MPa (T) reduced from 20 to 5 mm/h and (E) reduced from 1.5 to 1.0 mmol m⁻² s⁻¹. Within 10 days of restarting irrigation all these parameters were back to pre-drought levels. Both fruit and shoot growth came to a standstill within a week after drought was induced. During the first few days after re-watering, a high variability in Ψ_L was found between leaves from the same trees. This variability disappeared after six days. Shoot growth did not recover after re-watering but fruit growth rate, became the same as for continuously irrigated trees within days, but fruit size did not manage to recover before harvest. Yield from the dry trees was low because berry and pit weight were reduced by almost 50% at harvest, had a lower oil and percentage and were lower in phenolics. Stem sap flow was found to give a very good continuous measurement for the hydration status of the olive trees.     

A major ecosystem shift in the northern Bering Sea

Until recently, northern Bering Sea ecosystems were characterized by extensive seasonal sea ice cover, high water column and sediment carbon production, and tight pelagic-benthic coupling of organic production. Here, we show that these ecosystems are shifting away from these characteristics. Changes in biological communities are contemporaneous with shifts in regional atmospheric and hydrographic forcing. In the past decade, geographic displacement of marine mammal population distributions has coincided with a reduction of benthic prey populations, an increase in pelagic fish, a reduction in sea ice, and an increase in air and ocean temperatures. These changes now observed on the shallow shelf of the northern Bering Sea should be expected to affect a much broader portion of the Pacific-influenced sector of the Arctic Ocean.