Identifying Causal Effects of Nonbinary, Ordered Treatments using Multiple Instrumental Variables

This paper addresses the challenge of identifying causal effects of nonbinary, ordered treatments with multiple binary instruments. Next to presenting novel insights into the widely-applied two-stage least squares estimand, I show that a weighted average of local average treatment effects for combined complier populations is identified under the limited monotonicity assumption. This novel causal parameter has an intuitive interpretation, offering an appealing alternative to two-stage least squares. I employ recent advances in causal machine learning for estimation. I further demonstrate how causal forests can be used to detect local violations of the underlying limited monotonicity assumption. The methodology is applied to study the impact of community nurseries on child health outcomes

Transvaginal Ultrasonography in Ovarian Cancer Screening: Current Perspectives

Transvaginal ultrasonography (TVS) is an integral part of all major ovarian cancer screening trials. TVS is accurate in detecting abnormalities in ovarian volume and morphology, but is less reliable in differentiating benign from malignant ovarian tumors. When used as the only screening test, TVS is sensitive, but has a low positive predictive value. Therefore, serum biomarkers and tumor morphology indexing are used together with TVS to identify ovarian tumors at high risk for malignancy. This allows preoperative triage of high-risk cases to major cancer centers for therapy while decreasing unnecessary surgery for benign disease. Ovarian cancer screening has been associated with a decrease in stage at detection in most trials, thereby allowing treatment to be initiated when the disease is most curable

Holocene climate variability based on two lacustrine sediment sequences from Cádiz, southern Spain

Iberia, and especially southern Spain, has been the focus of only limited palaeoclimatological research. The scarcity of palaeoclimate archives has led to an interpolation of archives from distant sites. The palaeoclimate reconstruction of southern Spain is therefore mainly based on the interpolation of marine records from the Alboran Sea, the Gulf of Cádiz and the North Atlantic Ocean. The understanding of the impact and effects of Holocene changes is relatively poor. The execution of palaeoclimatological research in southern Spain has been hampered by the lack of suitable sites. This thesis contributes to the understanding of the Holocene climate change in southern Spain with two new cores drilled in shallow saline lakes. The arid southern Spain is a region without deep natural lakes, these ´salinas´ represent a promising alternative for palaeoclimate research. In this thesis, the methods and results of sedimentary and palaeoclimatological analyses of the modern lake sediment and soil catchment samples of Laguna de Medina, and the sediment sequences of Laguna de Medina and Laguna Salada are presented. The methods include XRF scanning, MSCL logging, particle-size analysis, total (in)organic carbonate analysis, determination of total sulphur, and total nitrogen, and XRD analysis, reinforced with the statistical method principal component analysis. The results are used to characterize the sediments and to interpret the changing climatological and environmental settings during the Holocene. The modern sediments of Laguna de Medina were studied with the same methods, to obtain a modern analogue for the long record. The primary objective of this thesis was to disentangle the Holocene climate of southern Spain, based on the lacustrine archives Laguna de Medina and Laguna Salada using 25.65 and 12 m long cores, respectively. Shifts in sedimentary deposition and geochemical proxies identify that southern Spain is highly vulnerable and responsive to climate change. Sedimentological, geochemical, mineralogical and granulometric analysis of the lacustrine sediment sequences provide a detailed palaeoclimatological and –hydrological reconstruction of the changes for the last 9,600 cal yr BP (Laguna de Medina) and 8,500 cal yr BP (Laguna Salada). Based on these two new lacustrine archives, this thesis provides the first high-resolution palaeoclimate reconstruction for southern Spain and a new archive for the Holocene from a shallow desiccated lake. The two cores provide insight in the Holocene climate evolution, which is divided into three stages in southern Spain: 1) the warm and arid Early Holocene, 2) the humid climatic optimum in the Middle Holocene, and 3) the progressive aridification trend in the Late Holocene. The high-resolution record of Laguna de Medina gives insight in the timing and duration of rapid climate changes (RCC´s) during the Holocene. Five arid periods 9,160-7,870, 5,780-4,800, 3,150-2,420, 1,950-1,450, and 1,264-550 cal yr BP and one humid period 550-170 cal yr BP could be identified and related to RCC in the Holocene. The sequence of Laguna de Medina reinforces the connection between global changes in the hydrological regime, rapid climate change and North Atlantic Oscillation dynamics

Predicting the mass spectrum of polymerizing linoleates using weighted random graph modeling

Biopolymers and biopolymer networks that form via autoxidation, like in drying of oil paint or fat degradation in food components, contain a large variety of monomeric building blocks. While the monomer variety complicates the modeling itself, obtaining experimental validation of infinite polymer networks is inherently difficult as well. A new model is developed, where an automated reaction network generation (ARNG) procedure is used to automatically generate the monomer components, structures and masses, and their reactions. This methodology is combined with random graph (RG) modeling to predict global polymer properties: distributions of numbers of monomer units and molar masses, gel point and gel fraction. This computational framework is applied to two model systems for linseed oil paint binder: the polymerization of ethyl linoleate (EL) and methyl linoleate (ML). A novel method was constructed to deal with the variability of monomer masses that complicates inferring molar mass from monomer number distribution. By modeling the polymer as a weighted random graph where the nodes contain information about the monomer masses in the system, the total weight of the finite connected components is computed. The predicted mass spectrum of finite connected components is used for validation with experimental data. A size exclusion chromatography (SEC) trace of ML is employed, which after calibration using the proposed framework, proves consistency between model and SEC data. The model provides a practical approach to both characterize complex biopolymers as polymers in terms of molar mass distribution and gel point, while preserving the information down to the level of monomeric units.</p

Uw mening over PraktijkKompas

De gemiddelde reactie is erg positief, maar er blijft voldoende ruimte voor verbetering

Fast two-layer two-photon imaging of neuronal cell populations using an electrically tunable lens

Functional two-photon Ca2+-imaging is a versatile tool to study the dynamics of neuronal populations in brain slices and living animals. However, population imaging is typically restricted to a single two-dimensional image plane. By introducing an electrically tunable lens into the excitation path of a two-photon microscope we were able to realize fast axial focus shifts within 15 ms. The maximum axial scan range was 0.7 mm employing a 40x NA0.8 water immersion objective, plenty for typically required ranges of 0.2–0.3 mm. By combining the axial scanning method with 2D acousto-optic frame scanning and random-access scanning, we measured neuronal population activity of about 40 neurons across two imaging planes separated by 40 μm and achieved scan rates up to 20–30 Hz. The method presented is easily applicable and allows upgrading of existing two-photon microscopes for fast 3D scanning

Развитие экстремального туризма в Крыму

Целью данной работы является на основе географического анализа факторов становления и особенностей развития экстремального туризма в Крыму разработать рекомендации по усовершенствованию данной отрасли туристской деятельности для создания привлекательного образа Крыма на международной арене

Robust nuclear lamina-based cell classification of aging and senescent cells

Changes in the shape of the nuclear lamina are exhibited in senescent cells, as well as in cells expressing mutations in lamina genes. To identify cells with defects in the nuclear lamina we developed an imaging method that quantifies the intensity and curvature of the nuclear lamina. We show that this method accurately describes changes in the nuclear lamina. Spatial changes in nuclear lamina coincide with redistribution of lamin A proteins and local reduction in protein mobility in senescent cell. We suggest that local accumulation of lamin A in the nuclear envelope leads to bending of the structure. A quantitative distinction of the nuclear lamina shape in cell populations was found between fresh and senescent cells, and between primary myoblasts from young and old donors. Moreover, with this method mutations in lamina genes were significantly distinct from cells with wild-type genes. We suggest that this method can be applied to identify abnormal cells during aging, in in vitro propagation, and in lamina disorders