Walker Lake Basin Data

Walker Lake Basin Data Name Date modified Time modified Size MB Extension Walker Lake Core 84-8 isotope and age data.xls 27.01.2018 15:25:52 0.03 xls Walker Lake core WL002 PSV age and chemical data.xlsx 09.02.2018 20:04:50 0.03 xlsx In the Walker Lake Basin folder: Depth, 14C age (not corrected for reservoir effect), 18O, 13C data for core 84-8 are reported in: Benson, L.V., 1988, Preliminary paleolimnologic data for the Walker Lake subbasin, California and Nevada: U.S. Geological Survey Water-Resources Investigations Report 87-4258, 50p. Palaeogeography, Palaeoclimatology, Palaeoecology, vol. 240, p. 497-507. Depth, PSV age, TIC , 18O, 13C data for core WL002 are reported in: Fasong Yuan , Braddock K. Linsley, Stephen S. Howe, Steve P. Lund, John P. McGeehin, 2006. Late Holocene lake-level fluctuations in Walker Lake, Nevada, USA. PSV data are the unpublished work of Steve Lund at USC. The data in this table has been incorporated in a paper by Lund and Benson that is “in revision”

Osteoblast activity is diminished in young Spontaneously Hypertensive Rats

Spontaneously Hypertensive Rats (SHR) are used as a genetic model of essential hypertension. Reductions in cortical and cancellous bone mass and increased bone turnover have been observed in aged SHR vs. Wistar-Kyoto (WKY) rats, normotensive genetics controls. In addition, antihypertensive aids have been effective in improving bone parameters in hypertensive rats. Thus, the relation between hypertension and bone remodeling warrants further attention. The purpose of this study was to determine how acute (i.e., 9 weeks) hypertension effects bone remodeling parameters (i.e., osteoclast and osteoblast activity). Methods: Right femora from 14-week-old SHR (n=5) and WKY (n=4) rats were dissected, fixed in 10% formalin and processed for bone histomorphometry for the examination of bone microarchitectural (bone volume/total volume ratio [BV/TV, %], trabecular thickness [Tb.Th, μm], trabecular number [Tb.N /mm] and trabecular separation [Tb. Sp, μm]) and bone static (osteoid surface/bone surface [OS/BS, %], osteoblast surface/bone surface [Ob.S/BS, %], number of osteoblast per total area [N.Ob/T.Ar], osteoclast surface/bone surface [Oc.S/BS, %)], and number of osteoclast per total area [N.Oc/T.Ar]) properties. Results: Body mass did not differ between SHR and WKY rats (i.e., 357 ± 6g vs. 351 ± 8g). No significant differences in bone microarchitectural properties (i.e., BV/TV, Tb.Th, Tb.N and Tb.Sp) were observed after acute hypertension. However, OS/BS, which represents newly formed yet unmineralized bone tissue, was significantly (p \u3c 0.05) reduced in SHR vs. WKY rats. In addition, osteoblast activity (Ob.S/BS) was significantly (p \u3c 0.05) diminished with hypertension. Further, there was a tendency (p = 0.08) for higher N.Oc/T.Ar in SHR vs. WKY rats. Conclusions: Results from this study indicate that hypertension alters bone remodeling parameters by decreasing osteoblast and increasing osteoclast activity. Differences in bone mircoarchitectural properties (i.e., BV/TV, Tb.Th, Tb.N and Tb.Sp) were not observed at this age; however, the alterations in bone cellular activity (i.e., OS/BS, Ob.S/BS and N.Oc/T.Ar) imply that reductions in bone mass are inevitable as the duration of hypertension increases

High-resolution record of climate change in the Owens Lake Basin, California, for the period 52,500 to 12,500 YBP

EXTRACT (SEE PDF FOR FULL ABSTRACT): High-resolution oxygen-18 and total inorganic carbon (TIC) studies of cored sediments from the Owens Lake Basin, California, indicate that Owens Lake was hydrologically open (overflowing) most of the time between 52,500 and 12,500 carbon-14 YBP. ... The lack of a strong correspondence between North Atlantic climate records and the Owens Lake delta-oxygen-18 record has two possible explanations: (1) the sequence of large and abrupt climate change indicated in North Atlantic records is not global in scope and is largely confined to the North Atlantic and surrounding areas, or (2) Owens Lake is located in a part of the Great Basin that is relatively insensitive to the effects of climate perturbations recorded in the North Atlantic region

Prolonged mixed phase induced by high pressure in MnRuP

Hexagonally structured MnRuP was studied under high pressure up to 35 GPa from 5 to 300 K using synchrotron X-ray diffraction. We observed that a partial phase transition from hexagonal to orthorhombic symmetry started at 11 GPa. The new and denser orthorhombic phase coexisted with its parent phase for an unusually long pressure range, {\Delta}P ~ 50 GPa. We attribute this structural transformation to a magnetic origin, where a decisive criterion for the boundary of the mixed phase lays in the different distances between the Mn-Mn atoms. In addition, our theoretical study shows that the orthorhombic phase of MnRuP remains steady even at very high pressures up to ~ 250 GPa, when it should transform to a new tetragonal phase.Comment: 15 pages, 5 figures, supplementary materia

Correlation of Late-Pleistocene Lake-Level Oscillations in Mono Lake, California, with North Atlantic Climate Events

Oxygen-18 (18O) values of sediment from the Wilson Creek Formation, Mono Basin, California, indicate three scales of temporal variation (Dansgaard-Oeschger, Heinrich, and Milankovitch) in the hydrologic balance of Mono Lake between 35,400 and 12,900 14C yr B.P. During this interval, Mono Lake experienced four lowstands each lasting from 1000 to 2000 yr. The youngest low stand, which occurred between 15,500 and 14,000 14C yr B.P., was nearly synchronous with a desiccation of Owens Lake, California. Paleomagnetic secular variation (PSV) data indicate that three of four persistent low stands occurred at the same times as Heinrich events HI, H2, and H4. 18O data indicate the two highest lake levels occurred ~18,000 and ~13,100 14C yr B.P., corresponding to passages of the mean position of the polar jet stream over the Mono Basin. Extremely low values of total inorganic carbon between 26,000 and 14,000 14C yr B.P. indicate glacial activity, corresponding to a time when summer insolation was much reduced

Implications of the problem orientated medical record (POMR) for research using electronic GP databases: a comparison of the Doctors Independent Network Database (DIN) and the General Practice Research Database (GPRD).

Background The General Practice Research Database (GPRD) and Doctor's Independent Network Database (DIN), are large electronic primary care databases compiled in the UK during the 1990s. They provide a valuable resource for epidemiological and health services research. GPRD (based on VAMP) presents notes as a series of discrete episodes, whereas DIN is based on a system (MEDITEL) that used a Problem Orientated Medical Record (POMR) which links prescriptions to diagnostic problems. We have examined the implications for research of these different underlying philosophies. Methods Records of 40,183 children from 141 practices in DIN and 76,310 from 464 practices in GRPD who were followed to age 5 were used to compare the volume of recording of prescribing and diagnostic codes in the two databases. To assess the importance and additional value of the POMR within DIN, the appropriateness of diagnostic linking to skin emollient prescriptions was investigated. Results Variation between practices for both the number of days on which prescriptions were issued and diagnoses were recorded was marked in both databases. Mean number of "prescription days" during the first 5 years of life was similar in DIN (19.5) and in GPRD (19.8), but the average number of "diagnostic days" was lower in DIN (15.8) than in GPRD (22.9). Adjustment for linkage increased the average "diagnostic days" to 23.1 in DIN. 32.7% of emollient prescriptions in GPRD appeared with an eczema diagnosis on the same day compared to only 19.4% in DIN; however, 86.4% of prescriptions in DIN were linked to an earlier eczema diagnosis. More specifically 83% of emollient prescriptions appeared under a problem heading of eczema in the 121 practices that were using problem headings satisfactorily. Conclusion Prescribing records in DIN and GPRD are very similar, but the usage of diagnostic codes is more parsimonious in DIN because of its POMR structure. Period prevalence rates will be underestimated in DIN unless this structure is taken into account. The advantage of the POMR is that in 121 of 141 practices using problem headings as intended, most prescriptions can be linked to a problem heading providing a specific reason for their issue

Holocene multidecadal and multicentennial droughts affecting Northern California and Nevada

Continuous, high-resolution δ18O records from cored sediments of Pyramid Lake, Nevada, indicate that oscillations in the hydrologic balance occurred, on average, about every 150 years (yr) during the past 7630 calendar years (cal yr). The records are not stationary; during the past 2740 yr, drought durations ranged from 20 to 100 yr and intervals between droughts ranged from 80 to 230 yr. Comparison of tree-ring-based reconstructions of climate change for the past 1200 yr from the Sierra Nevada and the El Malpais region of northwest New Mexico indicates that severe droughts associated with Anasazi withdrawal from Chaco Canyon at 820 cal yr BP (calendar years before present) and final abandonment of Chaco Canyon, Mesa Verde, and the Kayenta area at 650 cal yr BP may have impacted much of the western United States.During the middle Holocene (informally defined in this paper as extending from 8000 to 3000 cal yr BP), magnetic susceptibility values of sediments deposited in Pyramid Lake’s deep basin were much larger than late–Holocene (3000–0 cal yr BP) values, indicating the presence of a shallow lake. In addition, the mean δ18O value of CaCO3 precipitated between 6500 and 3430 cal yr BP was 1.6m less than the mean value of CaCO3 precipitated after 2740 cal yr BP. Numerical calculations indicate that the shift in the δ18O baseline probably resulted from a transition to a wetter (\u3e30%) and cooler (3–5 °C) climate. The existence of a relatively dry and warm middle-Holocene climate in the Truckee River– Pyramid Lake system is generally consistent with archeological, sedimentological, chemical, physical, and biological records from various sites within the Great Basin of the western United States. Two high-resolution Holocene-climate records are now available from the Pyramid and Owens lake basins which suggest that the Holocene was characterized by five climatic intervals. TIC and δ18O records from Owens Lake indicate that the first interval in the early Holocene (11,600–10,000 cal yr BP) was characterized by a drying trend that was interrupted by a brief (200 yr) wet oscillation centered at 10,300 cal yr BP. This was followed by a second early- Holocene interval (10,000–8000 cal yr BP) during which relatively wet conditions prevailed. During the early part of the middle Holocene (8000–6500 cal yr BP), high-amplitude oscillations in TIC in Owens Lake and d18O in Pyramid Lake indicate the presence of shallow lakes in both basins. During the latter part of the middle Holocene (6500–3800 cal yr BP), drought conditions dominated, Owens Lake desiccated, and Lake Tahoe ceased spilling to the Truckee River, causing Pyramid Lake to decline. At the beginning of the late Holocene (~3000 cal yr BP), Lake Tahoe rose to its sill level and Pyramid Lake increased in volume