855 research outputs found
Kidney stones: a fetal origins hypothesis
No full textKidney stones are common, with a multifactorial etiology involving dietary, environmental, and genetic factors. In addition, patients with nephrolithiasis are at greater risk of hypertension, diabetes mellitus, metabolic syndrome, and osteoporosis, although the basis for this is not fully understood. All of these renal stone–associated conditions have also been linked with adverse early-life events, including low–birth weight, and it has been suggested that this developmental effect is due to excess exposure to maternal glucocorticoids in utero. This is proposed to result in long-term increased hypothalamic-pituitary-axis activation; there are mechanisms through which this effect could also promote urinary lithogenic potential. We therefore hypothesize that the association between renal stone disease and hypertension, diabetes mellitus, metabolic syndrome, and osteoporosis may be related by a common pathway of programming in early life, which, if validated, would implicate the developmental origins hypothesis in the etiology of nephrolithiasis
Annual mean TROPOMI-derived ground-level NO2 mixing ratio (2019 - North America v1)
No full textAnnual mean ground-level NO2 mixing ratio for 2019 inferred from the TROPOMI satellite instrument over North America at 0.025x0.03125 degree resolution. Included is 2019 annual mean and 1.5 year mean spanning July 2018 – December 2019.
Reference:
Cooper, M.J., R.V. Martin, C.A. McLinden, and J.R. Brook (2020), Inferring ground-level nitrogen dioxide concentrations at fine spatial resolution applied to the TROPOMI satellite instrument, Env. Res. Lett., DOI:10.1088/1748-9326/aba3a
MONTANA - THE NEW R.V. SALES CAPITAL OF THE U.S.
No full textMotor home travelers across the country are flocking to Montana to purchase their luxury R.V.s as the vehicles are not subject to sales tax and registration fees are minimal. Some see this activity as tax evasion, but taxation expert Walter Hellerstein says its perfectly legal. To read the complete story, see The New York Times. The article title is The draw of Montana for the R.V. set? It\u27s not the Scenery. It was published on 8/17/05, and the author is Jim Robbins
MONTANA - THE NEW R.V. SALES CAPITAL OF THE U.S.
No full textMotor home travelers across the country are flocking to Montana to purchase their luxury R.V.s as the vehicles are not subject to sales tax and registration fees are minimal. Some see this activity as tax evasion, but taxation expert Walter Hellerstein says its perfectly legal. To read the complete story, see The New York Times. The article title is The draw of Montana for the R.V. set? It\u27s not the Scenery. It was published on 8/17/05, and the author is Jim Robbins
What is wrong with the DSM?
No full textThe DSM is the main classification of mental disorders used by psychiatrists in the United States and, increasingly, around the world. Although widely used, the DSM has come in for fierce criticism, with many commentators believing it to be conceptually flawed in a variety of ways. This paper assesses some of these philosophical worries. The first half of the paper asks whether the project of constructing a classification of mental disorders that �cuts nature at the joints� makes sense. What is mental disorder? Are types of mental disorder natural kinds (that is, are the distinctions between them objective and of fundamental theoretical importance, as are, say, the distinctions between the chemical elements)? The second half of the paper addresses epistemic worries. Even if types of mental disorder are natural kinds there may be reason to doubt that the DSM will come to reflect their natural structure. In particular, I examine the extent to which the DSM is theory-laden, and look at how it has been shaped by social and financial factors. Ultimately, I conclude that although the DSM is of immense practical importance it is not likely to become the best possible classification of mental disorders
Neighbor discovery in energy harvesting wireless sensor networks
No full textHomes, offices and vehicles are getting networked. This will enable context aware, autonomous operation of many support systems that could be controlled remotely. To achieve this there would be a large number of tiny devices -- sensors and actuators -- which are networked and they are termed generally as Internet of Things (IoT) devices. In future, they will be powered through harvested energy from the ambience to enable perennial lifetime and minimal manual maintenance. Some examples of energy sources are photovoltaic panels and piezoelectric crystals. Several challenges arise due to the nature of sources of energy. One of these challenges is that the devices (nodes) leave and re-enter networks due to fluctuating availability of harvested energy. This energy condition requires the adaptation of special means at every layer of the communication model. For example, as a result of fluctuating energy levels, the neighbor table maintained at each node changes quite often leading to complications in forming and maintaining routes. In fact initial neighbor discovery (ND) itself is a difficult task. Further, usage of directional antennas would affect the time taken to complete ND. Given the spatio-temporal variations in energy availability in harvesting environments, there are benefits of energy prediction. With the help of prediction, resource allocation within a single system and splitting of tasks between nodes in a network would be enhanced. In order to identify the various parameters that affect ND we first describe a generic analytical model of an energy harvesting device. Next, we study a network of these devices through exhaustive simulation study considering these various parameters. We demonstrate the benefits and challenges of using directional antennas for ND. We present a scheme that nodes could use to discover their neighbors during initial deployment and another scheme that could be used for subsequent discovery on re-entry into the network. We show that a dedicated ND protocol is necessary for energy harvesting networks and that directional ND is beneficial in these networks under some circumstances. Finally, we present light-weight energy prediction solutions that can be used to improve the performance of the ND process in particular.TelecommunicationElectrical EngineeringElectrical Engineering, Mathematics and Computer Scienc
Topology Control in Energy-harvesting Wireless Sensor Networks
No full textAmbient energy-harvesting technology is a promising approach to keep wireless sensor networks (WSNs) operating perennially. Depending on the harvesting source, nodes can either be active (alive) or inactive (dead) at any instant in such Energy-Harvesting WSNs (EH-WSNs). Thus, even in a static deployment of EH-WSNs, the network topology is no longer static. A popular method to increase energy-efficiency in WSNs is by employing topology control algorithms. Most of the topology control algorithms in the literature focus only on the transmission power while constructing a static topology without taking into account the residual energy of the nodes. Consequently, they cannot handle the situation when nodes have different energy levels, and when the number of active nodes varies with time in EH-WSN. Since the number of nodes alive in EH-WSNs is varying there is no possibility of having a centralized solution. To address this issue, we present two localized energy based topology control algorithms, viz., EBTC-1 and EBTC-2. EBTC-1 is for convergecast applications of WSNs and EBTC-2 is for a generic scenario where all nodes are required to be strictly connected. In some cases, to ensure fault tolerance the network may be required to be k-connected. While typical topology control algorithms select a particular number of neighbors, the distinguishing feature of both these algorithms is that they select neighbors based on energy levels, and render the global topology strongly-connected. Simulation results confirm that EBTC-1 and EBTC-2 reduce the transmission power and they let nodes have neighbors with high remaining energy. Results show that our proposed algorithms increase at least 33% in the remaining energy per neighbor. In addition, in terms of energy consumption and fault-tolerance, our proposed algorithms typically achieve 1-connected topology using 74% less energy compared to K-Neigh.Embedded SystemsSoftware and Computer TechnologyElectrical Engineering, Mathematics and Computer Scienc
Why Hacking is wrong about human kinds.
No full text�Human kind� is a term introduced by Ian Hacking to refer to the kinds of people�child abusers, pregnant teenagers, the unemployed�studied by the human sciences. Hacking argues that classifying and describing human kinds results in feedback, which alters the very kinds under study. This feedback results in human kinds having histories totally unlike those of natural kinds (such as copper, tigers and dandelions) leading Hacking to conclude that human kinds are radically unlike natural kinds. Here I argue that Hacking�s argument fails and that he has not demonstrated that human kinds cannot be natural kinds
Allocation of Opportunistic Spectrum for Cognitive Radio Ad hoc Networks
No full textCognitive Radios (CRs) address the problems of spectrum scarcity and under-utilization of the spectrum. However, realizing a CR network is neither easy nor straight-forward. The link layer in CR Ad hoc Networks is responsible for allocating suitable channels, out of the currently available channels. It is also responsible for setting up communication between nodes. Further, the spectrum efficiency should be maximized in a fair way. The problem of spectrum allocation can be modeled as a graph-theoretic problem. The selection of channels amongst the CR nodes in the network is an NP class problem. We prove this is, in fact, an NP complete problem. We propose a time-slotted system. In such a system, the schedule length needs to be kept to a minimum for higher spectrum utilization. We analyze the problem to determine conditions for an optimal allocation. We use edge coloring as a tool to analyze and propose heuristics. In ad hoc networks, distributed solutions are preferred due to the lack of infrastructure. We propose two distributed algorithms: (i) clique based, and (ii) localized heuristic algorithms. We compare the results of these heuristics with the algorithm proposed in literature. We also find the worst case bounds for these algorithms. For efficiency purposes, it is required to have a constant number of slots per frame. In such cases, producing a valid schedule is not enough since unfairness of allocation will eventually arise. To address this issue, we modify the edge coloring and clique based heuristics to produce valid fair schedules. Finally, we briefly consider the advantages of having a joint spectrum sensing-allocation scheme at the link layer. When the spectrum sensing scheme at the PHY layer is not completely reliable, a link layer scheme can help in reducing the false alarms and miss-detections. We, further constrain the system by limiting the number of channels that can be sensed within a frame. We present the spectrum utilization with this joint sensing-allocation policy.Wireless and Mobile CommunicationsTelecommunicationsElectrical Engineering, Mathematics and Computer Scienc
Anthrachinon uit koolteer
No full textDocument(en) uit de collectie Chemische ProcestechnologieDelftChemTechApplied Science
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