Mars' polar layered deposits record its climate history. However, no deposit yet analyzed provides a global water cycle record that can be tied to a specific orbital history. Here, I fill this gap by ...analyzing H2O ice layer formation in Mars' south polar Massive CO2 Ice Deposit (MCID), a 510,000‐year climate record. Statistical analyses of ∼109 formation model runs compared to observed stratigraphy indicate a variable H2O deposition rate of ∼1, 0.1, and 0.01 mm yr−1 at 20, 24, and 28° ^{\circ}$ obliquity, respectively—likely recording the obliquity‐dependent midlatitude‐to‐pole H2O transport rate. The MCID record allows unprecedented obliquity‐driven H2O ice deposition rate derivation because of its well‐defined age relative to other deposits and its CO2 cold‐trapping effect, which simplifies local seasonal and long‐term H2O flux. The recovery of an orbit‐resolved H2O transport rate is an essential step in elucidating Mars' global, orbit‐driven water cycle.
Plain Language Summary
Mars' south pole hosts a deposit of alternating CO2 and H2O ice layers, which contain a record of global H2O and CO2 transport as Mars' orbit evolved during the past 510 thousand years. I created a numerical model to simulate the build‐up of the layers over time and ran the model approximately one billion times, each time using a different governing function of H2O ice deposition as a function of Mars' orbital configuration. Using statistical analysis, I found that an H2O ice deposition function that exponentially decreases as a function of obliquity (spin‐axis tilt) best recreates the observed layer sequence. Recovery of a south polar H2O‐ice‐deposition‐versus‐obliquity function is novel and important for elucidating how Mars' global water cycle is driven by its orbital variations.
Key Points
H2O ice layers in Mars' Massive CO2 Ice Deposit record obliquity‐mediated rates of midlatitude‐to‐pole H2O transport over the past 510 kyr
The record's unique CO2 cold‐trapping environment isolates the orbit‐forcing signal from other processes, simplifying its interpretation
Orbit‐resolved H2O transport rates place an important new quantitative bound on processes driving Mars' recent (∼3.5 Myr) global water cycle
Summary
Capnography (ETCO2) is routinely used as a non‐invasive estimate of arterial carbon dioxide (PaCO2) levels in order to modify ventilatory settings, whereby it is assumed that there is a ...positive gap between PaCO2 and ETCO2 of approximately 0.5 kPa. However, negative values (ETCO2 > PaCO2) can be observed. We retrospectively analysed arterial to end‐tidal carbon dioxide differences in 799 children undergoing general anaesthesia with mechanical ventilation of the lungs in order to elucidate predictors for a negative gap. A total of 2452 blood gas analysis readings with complete vital sign monitoring, anaesthesia gas analysis and spirometry data were analysed. Mean arterial to end‐tidal carbon dioxide difference was −0.18 kPa (limits of 95% agreement −1.10 to 0.74) and 71.2% of samples demonstrated negative values. The intercept model revealed PaCO2 to be the strongest predictor for a negative PaCO2‐ETCO2 difference. A decrease in PaCO2 by 1 kPa resulted in a decrease in the PaCO2‐ETCO2 difference by 0.23 kPa. This study demonstrates that ETCO2 monitoring in children whose lungs are mechanically ventilated may paradoxically lead to overestimation of ETCO2 (ETCO2 > PaCO2) with a subsequent risk of unrecognised hypocarbia.
Irregular primes to 163 million BUHLER, J. P.; HARVEY, D.
Mathematics of computation,
10/2011, Letnik:
80, Številka:
276
Journal Article
Recenzirano
Odprti dostop
We compute all irregular primes less than 163 577 856. For all of these primes we verify that the Kummer-Vandiver conjecture holds and that the \lambda
Massive, kilometer thick deposits of carbon dioxide (CO2) ice have been detected at the south polar cap of Mars by radar investigations. These deposits are divided into several units that are ...separated by thin water ice bounding layers. Recent studies investigated the accumulation history of CO2 ice and found that the deposits most likely formed during several episodes in the past, when Martian obliquity was much lower than now. Those studies, while able to predict total volumes of CO2 ice consistent with those observed, did not attempt to explain the anomalous three‐dimensional distribution (thickness or extent) of CO2 ice or the ice's offset from the topographic high of the polar cap. In this paper we use a combination of feature analysis and numerical modeling to demonstrate that the CO2 deposits flow as glaciers and that glacial flow distributes the ice into its current position. Further, this distribution allows the ice to survive during high obliquity excursions.
Plain Language Summary
Carbon dioxide (CO2) ice is found in a stack of deposits at Mars' south pole. These deposits are situated in basins, where they reach more than 1 km thick. Previous work suggested that the CO2 ice should be deposited when the axial tilt of the planet was lower, making the poles colder than they are now; however, the thickness and distribution of this ice should be much thinner than observed if only atmospheric effects are working on the ice. Therefore, the CO2 ice deposit distribution cannot be explained by atmospheric deposition alone. In this paper, we use glacial modeling and feature analysis to demonstrate that glacial flow better explains the distribution of ice in its present state. In addition, we show that the slopes on the south polar cap act to focus glacial flow into the basins, where it can survive warm periods by sublimating only the uppermost sections when the tilt of the planet is larger than present day.
Key Points
Carbon dioxide ice has been mapped and modeled at the south pole of Mars
Deposition models cannot explain the volumetric distribution of CO2 ice, thickness, or distribution
We present geomorphic and modeling evidence that the CO2 deposits flow as glaciers into basins to reach their observed volumetric distribution
The concept of self-sensing active magnetic bearings (AMBs) is to eliminate the position sensors and estimate the position of the levitated object by measuring the bearing coil current. The main ...interest of this approach consists in reducing production costs and hardware complexity. Although the idea of self-sensing itself is not new and research has been carried out for years in this topic, it still remains a challenge. Many self-sensing methods have been proposed in literature, however they are all very delicate to realize. For this reason, there is still no industrial application for self-sensing magnetic bearings. This paper investigates the realization of a self-sensing AMB suitable for industrial use. The system must be robust and relatively low cost. In order to do that, this work explores a self-sensing configuration based on the current amplitude modulation. This approach is applied to an AMB test rig using reference sensors.
Rubus yellow net virus (RYNV) belongs to genus Badnavirus. Badnaviruses are found in plants as endogenous, inactive or activatable sequences, and/or in episomal (infectious and active) forms. To ...assess the state of RYNV in Rubus germplasm, we sequenced the genomes of various cultivars and mined eight raspberry whole genome datasets. Bioinformatics analysis revealed the presence of a diverse array of endogenous RYNV (endoRYNV) sequences that differ significantly in their structure; some lineages have nearly complete, yet non-functional genomes whereas others have rudimentary, short sequence fragments. We developed assays to genotype the main lineages as well as the only known episomal lineage present in the United States. This study discloses the widespread presence of endoRYNVs in commercial raspberries, likely because breeding efforts have focused on a limited pool of germplasm that harbored endoRYNVs.
A method is presented to correct positron emission tomography (PET) data for head motion during data acquisition. The method is based on simultaneous acquisition of PET data in list mode and ...monitoring of the patient's head movements with a motion tracking system. According to the measured head motion, the line of response (LOR) of each single detected PET event is spatially transformed, resulting in a spatially fully corrected data set. The basic algorithm for spatial transformation of LORs is based on a number of assumptions which can lead to spatial artifacts and quantitative inaccuracies in the resulting images. These deficiencies are discussed, demonstrated and methods for improvement are presented. Using different kinds of phantoms the validity and accuracy of the correction method is tested and its applicability to human studies is demonstrated as well.
Unbalance of magnetically levitated rotors causes undesirable synchronous vibrations which may lead to saturation of the magnetic actuator. To avoid this problem we propose a generalized narrow-band ...notch filter which is inserted into the multivariable feedback without destabilizing the closed loop. The parameters of the generalized notch filter strongly depend on the inverse sensitivity matrix evaluated at rotational speed. This matrix is easily measured a priori and stored in a look-up table. It is shown that a decentralized notch is feasible for weakly gyroscopic rotors. The proposed notch filter approach has advantages in terms of run-time complexity and analytical verification of closed-loop stability. Results from the implementation of the proposed unbalance compensation in industrial magnetic bearing systems are included.
Multiagent systems with workflows Vidal, J.M.; Buhler, P.; Stahl, C.
IEEE internet computing,
2004-Jan.-Feb., 2004-01-00, 20040101, Letnik:
8, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Industry and researchers have two different visions for the future of Web services. Industry wants to capitalize on Web service technology to automate business processes via centralized workflow ...enactment. Researchers are interested in the dynamic composition of Web services. We show how these two visions are points in a continuum and discuss a possible path for bridging the gap between them.
Prostate cancer is the most common cancer in men from Western industrialized countries and a significant proportion of patients progress to advanced metastatic disease, for which currently no ...curative treatment exists. Therefore, new therapeutic approaches need to be considered. Prostate specific membrane antigen (PSMA) is an integral, non-shed type 2 membrane protein that is highly and specifically expressed on prostate epithelial cells and strongly upregulated in prostate cancer. PSMA is also present in the neovasculature of other solid tumors. These findings have spurred the development of PSMA-targeted therapies and first-generation products have entered clinical testing. The proposed strategies range from targeted toxins and radionuclides to immunotherapeutic agents. The present review provides an overview of these approaches.
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