198 research outputs found
Holocene evolution of halite caves in the Cordillera de la Sal (Central Atacama, Chile) in different climate conditions
No full textGeomorphological studies have been carried out in rapidly evolving salt caves related to small watersheds in the
San Pedro de Atacama area, Chile. Radiocarbon ages of bones and wood from cave deposits, combined with the
presence of large salt caves, geomorphological and sedimentological observations, and the results of micrometer
measurements outside and in some of the caves, suggest a period of speleogenesis in the Cordillera de la Sal during
the onset of the Holocene, during which the large halite cave systems developed, followed by an early Holocene
hyperarid period.Most smaller caves (i.e. Lechuza del Campanario) most probably formed at the start of the
wetter mid-Holocene period (5–4.4 ka), when precipitation was never intense enough to entrain large amounts
of sediments, but enough to trigger cave development. A diamicton in Lechuza del Campanario Cave radiocarbon
dated at ca. 4.4 ka shows that at least one high intensity rainfall event occurred in this recharge basin during the
mid-Holocene wet interval. A wet period with lower intensity rainfall events followed between 4.0 and 2.5 ka,
causing the 4.4 kyrs old diamicton in Lechuza del Campanario Cave to be entrenched, and the alluvial fan at
the downstream end of Palacio del Sal Cave to be covered with windborne sediments dated by OSL at around
3.6 ka. At ca. 2 ka there was a high-intensity rainfall event documented by the age of a twig stuck in the ceiling
of the Palacio del Sal Cave, followed by a period with lower intensity rain events until ca. 1.3 ka, when another
intense flood produced a mudflow that deposited a second diamicton in Lechuza del Campanario Cave. From
then on clustering of radiocarbon ages forwood and bone recovered fromcaves indicates increased rainfall intensity
in the period ca. 0.9–0.5 ka, followed by no registered events until a minor flood at ca. 0.13 ka. The fourcenturies
long wetter time interval (0.9–0.5 ka), corresponding to the Medieval Climate Anomaly, has been an
archeologically important period in the Atacama Desert (Tiwanaku culture).
The observations and a detailed review of paleoclimate literature from this key area have allowed the development
of a landscape evolution model related to changing climate conditions during the Late Holocene
Douglas Fir Productivity Estimation Using Very High Spatial Resolution Imagery: A Case Study on Ground Treatment Impact in West Kootenay, British Columbia, Canada
No full textGeospatial Technologies & Natural Resource ManagementGeospatial Technologie
Canopy Vertical Parameters Estimation Using Unmanned Aerial Vehicle (UAV) Imagery
No full textGeospatial Technologies & Natural Resource ManagementGeospatial Technologie
Effects of Sintilimab Plus Radiotherapy on Levels of Spondin-2 and Glucose Transporter-1 in Patients with Cervical Cancer
No full textHuichun Yang, Zhengwen Chen, Hongyan Lou, Weijia Ying, Zeying Chai Department of Gynecology, Taizhou Hospital of Zhejiang Province Affiliated to Wenzhou Medical University, Linhai, Zhejiang Province, 317016, People’s Republic of ChinaCorrespondence: Zeying Chai, Department of Gynecology, Taizhou Hospital of Zhejiang Province Affiliated to Wenzhou Medical University, Linhai, Zhejiang Province, 317016, People’s Republic of China, Tel +86-013634092882, Email [email protected]: We aimed to evaluate the effects of sintilimab plus radiotherapy on levels of Spondin-2 and glucose transporter-1 (Glut-1) in patients with cervical cancer.Patients and Methods: A total of 112 patients with cervical cancer treated from January 2019 to January 2021 were selected in this randomized control trial and divided into a control group (n = 56) and a study group (n = 56) using the random number table method. Chemotherapy using docetaxel + cisplatin was performed for both groups, based on which the control group was given radiotherapy (external conformal radiotherapy + intracavitary irradiation), and the study group received sintilimab plus radiotherapy. The treatment lasted for six cycles, with 21 days as one cycle.Results: The total response rate of the study group was higher than that of the control group (55.36% vs 33.93%) (P 0.05). After six cycles of treatment, the levels of carcinoembryonic antigen, squamous cell carcinoma antigen, vascular endothelial growth factor-A, vascular endothelial growth factor receptor 2, Spondin-2 and Glut-1 decreased in both groups compared with those before treatment, and they were lower in the study group (P < 0.05). The survival rate of the study group was higher than that of the control group (87.50% vs 71.43%) (P < 0.05).Conclusion: Sintilimab plus radiotherapy can effectively reduce the levels of serum tumor markers, such as Spondin-2 and Glut-1, and enhance the clinical efficacy on patients with cervical cancer, without increasing adverse effects.Keywords: cervical cancer, glucose transporter-1, radiotherapy, sintilimab, spondin-
Design and Control of a Portable AO System: A Continuous Model Based Approach
No full textIn the field of Adaptive Optics (AO) a new development has been introduced recently: the Wavefront Sensorless Adaptive Optics (WFSless AO) approach, which only uses camera measurements to optimize image quality and does not use a Shack-Hartman (SH) Wavefront Sensor (WFS) [Booth, 2006, Débarre et al., 2009, Hinnen et al., 2008]. In order to optimize the image quality of a point source or an extended object, the residual wavefront should be minimised as much as possible. The Model Based Approach [Booth, 2007, Linhai and Rao, 2011] is a very promising approach which can be used for this optimisation, resulting in a significant reduction in the amount of measurements. This approach uses an initial measurement and then excites all the modes that need to be optimised separately and takes a measurement of the intensity distribution after each excitation. Then, the Second-Moment (SM)’s of the measured intensity distributions are computed and used for the computation of the optimal control input, which is the coefficient vector in a Zonal representation of the wavefront. The control vector can be used to minimise the residual wavefront and thus optimise the image quality. However, in this approach it is assumed that the incoming wavefront does not change between the first and last measurement. This assumption is called the frozen window time and it is not valid for real-time problems. In [Lianghua et al., 2017] a solution was proposed for this problem, by using a precomputed independent set of modes, which allows a decoupling of the modes and computations and reduces the frozen window time. Unfortunately, this research introduces more measurements which leads to more delay. In this thesis a new approach will be presented, the Continuous Model Based Approach. This approach tries to solve both problems simultaneously: a reduction of the number of measurements and a reduction of the frozen window time. The number of measurements will be reduced by combining the excitation and optimisation step and the frozen window time will be reduced by using a two step optimisation, based on [Lianghua et al., 2017]. First, the validity of this approach will be proven mathematically and with simulations, then it will be tested in experiments. In order to make the step to real-time experiments, also an online calibration method will be introduced, proven and tested. This is also a new technique, based on the Model Based Approach [Linhai and Rao, 2011] and can be used to obtain the correlation matrix for any set of modes, focussed on actuator responses.Mechanical Engineering | Systems and Contro
Oxidative dehydrogenation of n-butane to butenes on Mo-doped VMgO catalysts
No full textVMgO catalysts with different molybdenum doping amounts were prepared by an impregnation method. The structure, specific surface area, and basic and redox properties of these catalysts were determined by XRD, BET, CO2-TPD, and H-2-TPR. The XRD results revealed that all catalysts contained an orthovanadate phase (Mg-3(VO4)(2)), while no metavanadate and pyrovanadate phases were detected. BET surface area analysis showed that the Mo-doped catalysts possessed lower surface areas than the undoped one. The reducing and basicity properties of the catalysts were characterized by H2-TPR and CO2-TPD measurements, which demonstrated that Mo-doping improved the redox temperature and reduced the number of basic sites. The performances of these catalysts were investigated at different C4H10/O-2 molar ratios, temperatures, and contact times. The Mo-doping not only improved the selectivity of butenes but also inhibited the deep oxidation reactions, although cracking reactions occurred with high levels of Mo doping. When the Mo/V atomic ratio was 3 : 100, n-butane conversion of 34.5% and total butene selectivity of 79.3% were achieved at 630 degrees C. To the best of our knowledge, the oxidative dehydrogenation performance of the synthesized Mo-doped VMgO catalysts described in this work represents a remarkable improvement compared to previous reports
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