94 research outputs found
A System Dynamics Model of Cyclical Office Oversupply
No full textThis article explores office market system dynamics through a simple simulation model. Model lag and adjustment parameters similar to real office markets generate explosive cycles. Simulations show that deviations from equilibrium can be reduced by changing the information structure of the system. System dynamics, principle/agent conflicts, a prisoners’ dilemma game, faulty information (poor forecasting, market research and valuation techniques), regulatory institutions, and differing equilibria in office space and financial markets all contribute to allocative inefficiency. Thinking of office markets as a "managed feedback control system" may be a useful representation of the oversupply problem. Leverage points for system improvement may be a municipal "queue" to address agency and prisoner's dilemma problems, improved forecasting techniques and more reliance on forecasting.
The mitochondrial calcium uniporter regulates breast cancer progression via HIF-1α
No full textTriple-negative breast cancer (TNBC) represents the most aggressive breast tumor subtype. However, the molecular determinants responsible for the metastatic TNBC phenotype are only partially understood. We here show that expression of the mitochondrial calcium uniporter (MCU), the selective channel responsible for mitochondrial Ca(2+) uptake, correlates with tumor size and lymph node infiltration, suggesting that mitochondrial Ca(2+) uptake might be instrumental for tumor growth and metastatic formation. Accordingly, MCU downregulation hampered cell motility and invasiveness and reduced tumor growth, lymph node infiltration, and lung metastasis in TNBC xenografts. In MCU-silenced cells, production of mitochondrial reactive oxygen species (mROS) is blunted and expression of the hypoxia-inducible factor-1α (HIF-1α) is reduced, suggesting a signaling role for mROS and HIF-1α, downstream of mitochondrial Ca(2+) Finally, in breast cancer mRNA samples, a positive correlation of MCU expression with HIF-1α signaling route is present. Our results indicate that MCU plays a central role in TNBC growth and metastasis formation and suggest that mitochondrial Ca(2+) uptake is a potential novel therapeutic target for clinical intervention
Aspects of digital HDTV systems
No full textS.278-85A high definition television system with double line rate, digital transmission to the subscriber and digital signal processing including frame stores at the studio and in the home receiver allows a large viewing angle and a viewing distance of twice the picture height and thus differs clearly from other systems aiming at improved quality within existing standards. In relation to such a system the author analyzes possibilities of signal transmission and discusses methods of signal processing and coding providing high image quality and resolution at moderate transmission rates. An experimental setup for investigation of real time signal processing is described.37Nr.11-1
On the extent of the moat flow in axisymmetric sunspots
No full textUnipolar, axisymmetric sunspots are figuratively called “theoretician's sunspots” because their simplicity supposedly makes them more suitable for theoretical descriptions or numerical models. On November 18, 2013, a very large specimen (active region NOAA 11899) crossed the central meridian of the sun. The moat flow associated with this very large spot is quantitatively compared to that of a medium and a small sunspot to determine the extent of the moat flow in different environments. We employ continuum images and magnetograms of the Helioseismic and Magnetic Imager (HMI) as well as extreme ultraviolet (EUV) images at λ160 nm of the Atmospheric Imaging Assembly (AIA), both on board the Solar Dynamics Observatory (SDO), to measure horizontal proper motions with Local Correlation Tracking (LCT) and flux transport velocities with the Differential Affine Velocity Estimator (DAVE). We compute time-averaged flow maps (±6 hr around meridian passage) and radial averages of photometric, magnetic, and flow properties. Flow fields of a small- and a medium-sized axisymmetric sunspot provide the context for interpreting the results. All sunspots show outward moat flow and the advection of moving magnetic features (MMFs). However, the extent of the moat flow varies from spot to spot, and a correlation of flow properties with size is tenuous, if at all present. The moat flow is asymmetric and predominantly in the east–west direction, whereby deviations are related to the tilt angle of the sunspot group as well as to the topology and activity level of the trailing plage
Quantitative Understanding of Microseismicity for Reservoir Characterization and Development
No full textA calcium optimum for cytotoxic T lymphocyte and natural killer cell cytotoxicity
No full textCytotoxic T lymphocytes (CTLs) and natural killer (NK) cells are required to eliminate cancer cells. We analysed the Ca2+ dependence of CTL and NK cell cytotoxicity and found that in particular CTLs have a very low optimum of [Ca2+ ]i (between 122 and 334 nm) and [Ca2+ ]o (between 23 and 625 μm) for efficient cancer cell elimination, well below blood plasma Ca2+ levels. As predicted from these results, partial down-regulation of the Ca2+ channel Orai1 in CTLs paradoxically increases perforin-dependent cancer cell killing. Lytic granule release at the immune synapse between CTLs and cancer cells has a Ca2+ optimum compatible with this low Ca2+ optimum for efficient cancer cell killing, whereas the Ca2+ optimum for CTL migration is slightly higher and proliferation increases monotonously with increasing [Ca2+ ]o . We propose that a partial inhibition of Ca2+ signals by specific Orai1 blockers at submaximal concentrations could contribute to tumour elimination
Redox regulation of calcium ion channels: Chemical and physiological aspects
No full textReactive oxygen species (ROS) are increasingly recognized as second messengers in many cellular processes.
While high concentrations of oxidants damage proteins, lipids and DNA, ultimately resulting in
cell death, selective and reversible oxidation of key residues in proteins is a physiological mechanism
that can transiently alter their activity and function. Defects in ROS producing enzymes cause disturbed
immune response and disease.
Changes in the intracellular free Ca2+ concentration are key triggers for diverse cellular functions. Ca2+
homeostasis thus needs to be precisely tuned by channels, pumps, transporters and cellular buffering
systems. Alterations of these key regulatory proteins by reversible or irreversible oxidation alter the
physiological outcome following cell stimulation. It is therefore necessary to understand which proteins
are regulated and if this regulation is relevant in a physiological- and/or pathophysiological context.
Because ROS are inherently difficult to identify and to measure, we first review basic oxygen redox
chemistry and methods of ROS detection with special emphasis on electron paramagnetic resonance
(EPR) spectroscopy. We then focus on the present knowledge of redox regulation of Ca2+ permeable ion
channels such as voltage-gated (CaV) Ca2+ channels, transient receptor potential (TRP) channels and Orai
channels
Relationship between personality type and the ability to be a change agent
No full textPlan BThis descriptive study investigated the relationship between personality types as indicated on the Myer’s Briggs Type Indicator and the ability to be a change agent as measured by the Change Agent Inventory. The Myer’s Briggs Type Indicator (MBTI) Form G is a questionnaire designed to make Carl Jung’s theory of psychological types understandable and useful in everyday life. The author, Katharine Cook Briggs (1875-1968) and her daughter, Isabel Briggs Myers (1897-1980) were disciplined observers of human personality differences. They studied and elaborated the ideas of Jung, and applied them to human interaction. After more than 50 years of research and development, the current MBTI is the most widely used instrument for understanding normal personality differences. The Change Agent Inventory (CAI) provides a comprehensive assessment of the criteria and characteristics necessary to successfully implement key business changes in an organization. It can be used to assess individuals charged with the responsibility to make sure a change happens; and to select primary change agents for major change projects. The CAI was developed by Implementation Management Associates, Inc. of Brighton, Colorado. After these two instruments were taken by members of the College Operating Team (COT), a focus group was conducted with these questions asked of each member: What is your attitude toward change? Do you like or dislike change? Why? How effective are you as a change agent? The participants in this study were nine managers at a two-year technical college. The WITC - New Richmond COT has a variety of personality preferences. All the COT members demonstrated a higher than average capacity for change. There was a tendency for more intuitive managers to score higher on the change agent instrument. There was also a tendency for the higher the score on the change agent instrument the lower the MBTI Type S score. However, there did appear to be a positive relationship between the focus group responses and CAI scores
Petrophysical and mechanical rock property database of the Los Humeros and Acoculco geothermal fields (Mexico)
No full textPetrophysical and mechanical rock properties are key parameters for the characterization of the deep subsurface in different disciplines such as geothermal heat extraction, petroleum reservoir engineering or mining. They are commonly used for the interpretation of geophysical data and the parameterization of numerical models and thus are the basis for economic reservoir assessment. However, detailed information regarding petrophysical and mechanical rock properties for each relevant target horizon is often scarce, inconsistent or distributed over multiple publications. Therefore, subsurface models are often populated with generalized or assumed values resulting in high uncertainties. Furthermore, diagenetic, metamorphic and hydrothermal processes significantly affect the physiochemical and mechanical properties often leading to high geological variability. A sound understanding of the controlling factors is needed to identify statistical and causal relationships between the properties as a basis for a profound reservoir assessment and modeling. Within the scope of the GEMex project (EU H2020, grant agreement no. 727550), which aims to develop new transferable exploration and exploitation approaches for enhanced and super-hot unconventional geothermal systems, a new workflow was applied to overcome the gap of knowledge of the reservoir properties. Two caldera<span idCombining double low line"page572"/> complexes located in the northeastern Trans-Mexican Volcanic Belt - the Acoculco and Los Humeros caldera - were selected as demonstration sites. The workflow starts with outcrop analog and reservoir core sample studies in order to define and characterize the properties of all key units from the basement to the cap rock as well as their mineralogy and geochemistry. This allows the identification of geological heterogeneities on different scales (outcrop analysis, representative rock samples, thin sections and chemical analysis) enabling a profound reservoir property prediction. More than 300 rock samples were taken from representative outcrops inside the Los Humeros and Acoculco calderas and the surrounding areas and from exhumed "fossil systems" in Las Minas and Zacatlán. Additionally, 66 core samples from 16 wells of the Los Humeros geothermal field and 8 core samples from well EAC1 of the Acoculco geothermal field were collected. Samples were analyzed for particle and bulk density, porosity, permeability, thermal conductivity, thermal diffusivity, and heat capacity, as well as ultrasonic wave velocities, magnetic susceptibility and electric resistivity. Afterwards, destructive rock mechanical tests (point load tests, uniaxial and triaxial tests) were conducted to determine tensile strength, uniaxial compressive strength, Young's modulus, Poisson's ratio, the bulk modulus, the shear modulus, fracture toughness, cohesion and the friction angle. In addition, X-ray diffraction (XRD) and X-ray fluorescence (XRF) analyses were performed on 137 samples to provide information about the mineral assemblage, bulk geochemistry and the intensity of hydrothermal alteration. An extensive rock property database was created (Weydt et al., 2020; <a hrefCombining double low line"https://doi.org/10.25534/tudatalib-201.10">https://doi.org/10.25534/tudatalib-201.10</a>), comprising 34 parameters determined on more than 2160 plugs. More than 31 000 data entries were compiled covering volcanic, sedimentary, metamorphic and igneous rocks from different ages (Jurassic to Holocene), thus facilitating a wide field of applications regarding resource assessment, modeling and statistical analyses..Reservoir Engineerin
- …
