Reservations about Qualitiative Models

Very little of the knwoledge that an operator of a complex physical system brings to the job is purely quantitative in form. Virtually all of an operator's knowledge can be represented as qualitative relations or quasi-quantitative relations such as rough proportionalities. The realization that computer-based Instruction syste,s need to provide instructions and explanations In terms that students can use, that is, often in qualitative terms, has led to recent efforts in cognitive science and artificial intelligence to develop qualitative simulation models of complex dynamic systems. In this paper we discuss theoretical and pragmatic problems involved in using qualitative models to support automated explanation facilities

Teacher Termination and Nonrenewal in Texas Public Schools Symposium on Education Law.

Abstract Forthcoming

Light, stratification and zooplankton as controlling factors for the spring development of phytoplankton in Lake Constance

The patterns of phytoplankton growth and decline during the spring bloom and the following clear-water phase in Lake Constance have been studied on the basis of cell counts with short-term sampling intervals and related to light climate, stratification and zooplankton pressure

An Action-Based Approach to Presence: Foundations and Methods

This chapter presents an action-based approach to presence. It starts by briefly describing the theoretical and empirical foundations of this approach, formalized into three key notions of place/space, action and mediation. In the light of these notions, some common assumptions about presence are then questioned: assuming a neat distinction between virtual and real environments, taking for granted the contours of the mediated environment and considering presence as a purely personal state. Some possible research topics opened up by adopting action as a unit of analysis are illustrated. Finally, a case study on driving as a form of mediated presence is discussed, to provocatively illustrate the flexibility of this approach as a unified framework for presence in digital and physical environment

Complement activation predicts negative outcomes in COVID-19: The experience from Northen Italian patients

Coronavirus disease 19 (COVID-19) may present as a multi-organ disease with a hyperinflammatory and prothrombotic response (immunothrombosis) in addition to upper and lower airway involvement. Previous data showed that complement activation plays a role in immunothrombosis mainly in severe forms. The study aimed to investigate whether complement involvement is present in the early phases of the disease and can be predictive of a negative outcome. We enrolled 97 symptomatic patients with a positive RT-PCR for SARS-CoV-2 presenting to the emergency room. The patients with mild symptoms/lung involvement at CT-scan were discharged and the remaining were hospitalized. All the patients were evaluated after a 4-week follow-up and classified as mild (n. 54), moderate (n. 17) or severe COVID-19 (n. 26). Blood samples collected before starting any anti-inflammatory/immunosuppressive therapy were assessed for soluble C5b-9 (sC5b-9) and C5a plasma levels by ELISA, and for the following serum mediators by ELLA: IL-1β, IL-6, IL-8, TNFα, IL-4, IL-10, IL-12p70, IFNγ, IFNα, VEGF-A, VEGF-B, GM-CSF, IL-2, IL-17A, VEGFR2, BLyS. Additional routine laboratory parameters were measured (fibrin fragment D-dimer, C-reactive protein, ferritin, white blood cells, neutrophils, lymphocytes, monocytes, platelets, prothrombin time, activated partial thromboplastin time, and fibrinogen). Fifty age and sex-matched healthy controls were also evaluated. SC5b-9 and C5a plasma levels were significantly increased in the hospitalized patients (moderate and severe) in comparison with the non-hospitalized mild group. SC5b9 and C5a plasma levels were predictive of the disease severity evaluated one month later. IL-6, IL-8, TNFα, IL-10 and complement split products were higher in moderate/severe versus non-hospitalized mild COVID-19 patients and healthy controls but with a huge heterogeneity. SC5b-9 and C5a plasma levels correlated positively with CRP, ferritin values and the neutrophil/lymphocyte ratio. Complement can be activated in the very early phases of the disease, even in mild non-hospitalized patients. Complement activation can be observed even when pro-inflammatory cytokines are not increased, and predicts a negative outcome

Surface and Interface Effects in VLSI

ABSTRACT The effect of cation on the CdSe/polysulfide photoelectrochemical (PEC) solar cell has been investigated. The currentpotential response of the polysulfide electrolyte on a platinum electrode was measured as a function of the alkali metal cation in solution. There was a -33 mV shift in the redox potential and an increase in the current when the cation was changed from Na § to Cs § The performance of the CdSe/polysulfide PEC cell with both polycrystalline and single-crystal semiconductor electrodes increased in the open-circuit potential, the short-circuit current, the fill factor, and the energy conversion efficiency when Cs polysulfide was used as compared with K or Na polysulfide. Impedance measurements were made on the electrodes in polysulfide solutions and hydroxide solutions with the different cations. The results for both electrolytes showed a negative shift in the flatband potential, an increase in the apparent charge-carrier concentration, and an increase in the frequency dispersion of the measurements with the addition of Cs +. The impedance measurements also showed a dependence on the orientation of the CdSe crystal. The effects above are related to a combination of a change in the solution and the surface of the semiconductor. The stoichiometric distribution of the polysulfide species changes with the addition of Cs + and the surface of the semiconductor changes, facilitating charge transfer across the semiconductor/ electrolyte interface. Initial work on the cadmium chalcogenide/polysulfide PEC solar cell was published by Gerischer ~ and Ellis et aI.2 A great deal of work has been performed since those original studies on improvements to the semiconductor, the surface condition of the semiconductor electrode, and the electrolyte. CdS, CdSe, CdTe and mixed CdSe~T%x 3-~ have been investigated to increase the energy-conversion efficiency and stability of the PEC cells. Several researchers have investigated cadmium chalcogenide PEC solar cells using polycrystalline electrodes. Long-term stabilities have been demonstrated with conversion efficiencies up to 5% for polycrystalline CdSe. 7-1~ The semiconductor/liquid junction solar cell is particularly well suited to low cost polycrystalline electrodes. Changes in the make-up of the polysulfide electrolyte have a large effect on the performance of the solar cell; the effect of hydroxide ion concentration and the sulfideto-sulfur ratio have been investigated by some researchers.~l~ Both the hydroxide ion and the sulfur-to-sulfide ratio affect the equilibrium concentration of the electroactive species, the stability of the solution, and the light absorption by the solution. Changing the cation in the solution leads to changes in the performance of the cell. ~6-~9 The cation is not involved directly in the redox reactions at the semiconductor electrode but the performance of the cell increases significantly when the cation in solution is changed from Na § or K § to Cs § The improvement is in the stability of the semiconductor, the open-circuit photovoltage (Voc) and the photocurrent response. The flatband potential (V~) also shifts negative with the addition of Cs*; yet the only difference between the cations is the ionic radius and thus the charge density. The change in cation can affect the surface of the semiconductor by altering the degree of adsorption, or by incorporation into the semicon-* Electrochemical Society Active Member. a Present address: IBM Corporation, Hopewell Junction, New York 12533-6531. ductor itself; or by changing the activity of the species in solution, or the distribution of the polysulfide species. The CdSe/polysulfide system is examined here. First, the current-potential response of polysulfide on a platinum electrode was measured. Impedance measurements then were made to determine how the change in cation affects the band energies and charge-carrier concentration of the semiconductor. The measurements were made in a variety of systems to separate the different effects: CdSe singlecrystal electrodes in hydroxide electrolytes with the different cations, CdSe single-crystal electrodes in polysulfide with the different cations, and with CdSe polycrystalline electrodes in polysulfide. The impedance measurements indicate changes in the performance of both single-crystal and polycrystalline CdSe/polysulfide PEC cells with the different cations. Polysulfide Electrolyte Polysulfide solutions have been studied extensively in the pulp and paper industry. The equilibrium relationships of the solution species are presented in The electroactive species and rate-limiting step at the photoanode have been the subject of several papers. 14' 24-2~ I

Towards ‘Onlife’ Education. How Technology is Forcing Us to Rethink Pedagogy

[EN] The objective of this chapter is twofold: on the one hand, to provide an explanation for the need we have today to rethink pedagogy based on new realities and the scenarios in which we live, also in education, generated by the technology of our time and, on the other hand, to point out the direction in which we can find a path that leads us to that reflection in the face of the inevitable convergence between technology and pedagogy in which we are today

Rolled-Up Nanotech: Illumination-Controlled Hydrofluoric Acid Etching of AlAs Sacrificial Layers

<p>Abstract</p> <p>The effect of illumination on the hydrofluoric acid etching of AlAs sacrificial layers with systematically varied thicknesses in order to release and roll up InGaAs/GaAs bilayers was studied. For thicknesses of AlAs below 10 nm, there were two etching regimes for the area under illumination: one at low illumination intensities, in which the etching and releasing proceeds as expected and one at higher intensities in which the etching and any releasing are completely suppressed. The &#8220;etch suppression&#8221; area is well defined by the illumination spot, a feature that can be used to create heterogeneously etched regions with a high degree of control, shown here on patterned samples. Together with the studied self-limitation effect, the technique offers a way to determine the position of rolled-up micro- and nanotubes independently from the predefined lithographic pattern.</p

Lack of the Long Pentraxin PTX3 Promotes Autoimmune Lung Disease but not Glomerulonephritis in Murine Systemic Lupus Erythematosus

The long pentraxin PTX3 has multiple roles in innate immunity. For example, PTX3 regulates C1q binding to pathogens and dead cells and regulates their uptake by phagocytes. It also inhibits P-selectin-mediated recruitment of leukocytes. Both of these mechanisms are known to be involved in autoimmunity and autoimmune tissue injury, e.g. in systemic lupus erythematosus, but a contribution of PTX3 is hypothetical. To evaluate a potential immunoregulatory role of PTX3 in autoimmunity we crossed Ptx3-deficient mice with Fas-deficient (lpr) C57BL/6 (B6) mice with mild lupus-like autoimmunity. PTX3 was found to be increasingly expressed in kidneys and lungs of B6lpr along disease progression. Lack of PTX3 impaired the phagocytic uptake of apoptotic T cells into peritoneal macrophages and selectively expanded CD4/CD8 double negative T cells while other immune cell subsets and lupus autoantibody production remained unaffected. Lack of PTX3 also aggravated autoimmune lung disease, i.e. peribronchial and perivascular CD3+ T cell and macrophage infiltrates of B6lpr mice. In contrast, histomorphological and functional parameters of lupus nephritis remained unaffected by the Ptx3 genotype. Together, PTX3 specifically suppresses autoimmune lung disease that is associated with systemic lupus erythematosus. Vice versa, loss-of-function mutations in the Ptx3 gene might represent a genetic risk factor for pulmonary (but not renal) manifestations of systemic lupus or other autoimmune diseases

Collective consciousness and its pathologies: Understanding the failure of AIDS control and treatment in the United States

We address themes of distributed cognition by extending recent formal developments in the theory of individual consciousness. While single minds appear biologically limited to one dynamic structure of linked cognitive submodules instantiating consciousness, organizations, by contrast, can support several, sometimes many, such constructs simultaneously, although these usually operate relatively slowly. System behavior remains, however, constrained not only by culture, but by a developmental path dependence generated by organizational history, in the context of market selection pressures. Such highly parallel multitasking – essentially an institutional collective consciousness – while capable of reducing inattentional blindness and the consequences of failures within individual workspaces, does not eliminate them, and introduces new characteristic malfunctions involving the distortion of information sent between workspaces and the possibility of pathological resilience – dysfunctional institutional lock-in. Consequently, organizations remain subject to canonical and idiosyncratic failures analogous to, but more complicated than, those afflicting individuals. Remediation is made difficult by the manner in which pathological externalities can write images of themselves onto both institutional function and corrective intervention. The perspective is applied to the failure of AIDS control and treatment in the United States