Ground Source Heat Pump Sub-Slab Heat Exchange Loop Performance in a Cold Climate

This report presents a cold-climate project that examines an alternative approach to ground source heat pump (GSHP) ground loop design. The innovative ground loop design is an attempt to reduce the installed cost of the ground loop heat exchange portion of the system by containing the entire ground loop within the excavated location beneath the basement slab. Prior to the installation and operation of the sub-slab heat exchanger, energy modeling using TRNSYS software and concurrent design efforts were performed to determine the size and orientation of the system. One key parameter in the design is the installation of the GSHP in a low-load home, which considerably reduces the needed capacity of the ground loop heat exchanger. This report analyzes data from two cooling seasons and one heating season. Upon completion of the monitoring phase, measurements revealed that the initial TRNSYS simulated horizontal sub-slab ground loop heat exchanger fluid temperatures and heat transfer rates differed from the measured values. To determine the cause of this discrepancy, an updated model was developed utilizing a new TRNSYS subroutine for simulating sub-slab heat exchangers. Measurements of fluid temperature, soil temperature, and heat transfer were used to validate the updated model

Open Systems Viewed Through Their Conservative Extensions

A typical linear open system is often defined as a component of a larger conservative one. For instance, a dielectric medium, defined by its frequency dependent electric permittivity and magnetic permeability is a part of a conservative system which includes the matter with all its atomic complexity. A finite slab of a lattice array of coupled oscillators modelling a solid is another example. Assuming that such an open system is all one wants to observe, we ask how big a part of the original conservative system (possibly very complex) is relevant to the observations, or, in other words, how big a part of it is coupled to the open system? We study here the structure of the system coupling and its coupled and decoupled components, showing, in particular, that it is only the system's unique minimal extension that is relevant to its dynamics, and this extension often is tiny part of the original conservative system. We also give a scenario explaining why certain degrees of freedom of a solid do not contribute to its specific heat.Comment: 51 page

Prognostic Factors for Amputation or Death in Patients Submitted to Vascular Surgery for Acute Limb Ischemia

Clebes Fagundes1, Flávio Danni Fuchs2, Almondi Fagundes1, Ronaldo A Poerschke1, Maurício Z Vacaro11Divisions of Vascular Surgery, Hospital São Vicente de Paulo, Faculdade de Medicina da Universidade de Passo Fundo; 2Cardiology, Hospital de Clínicas de Porto Alegre, Faculdade de Medicina da Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, BrazilObjective: To investigate the risk profile of patients with thrombosis and emboli, and prognostic factors for death or amputation in patients presenting with acute limb ischemia in a tertiary care regional hospital in Brazil.Methods: A prospectively planned cohort study was carried out in which 83 patients with acute limb ischemia, secondary to thrombosis, or embolism, classified in stages II and III of severity were evaluated. Univariate analysis and logistic regression models were used to explore the relationship between anthropometric and demographic characteristics, comorbidities, cardiovascular risk factors, duration of occlusion, and type of surgery with the incidence of amputation or death, which were evaluated in 30 days and 1 year thereafter.Results: Male gender, smoking, and comorbidities were more frequent among patients with thrombosis, and atrial fibrillation was more common among patients with embolism. Occlusion longer than 24 hours (odds ratio [OR] 2.6, 95% confidence interval [CI] 1.1–7.6) and a trend for diabetes (RR 2.6, 95% CI 0.9–7.5) were the characteristics associated with death or amputation in the multivariate analysis, which occurred in 15 (18.1%) and 24 (28.9%) of the participants, respectively. Reperfusion injury was a risk factor for death but not for amputation (OR 16.9, 95% CI 1.1–232.9) after adjustment for age, duration of occlusion, and diabetes.Conclusions: Traditional and avoidable risk factors explain the occurrence of thrombosis and embolism in our region. Access to medical care is the most important and modifiable prognostic factor for death or amputation.Keywords: acute limb ischemia, embolism, thrombosis, prognostic factor

On the Atomic Photoeffect in Non-relativistic QED

In this paper we present a mathematical analysis of the photoelectric effect for one-electron atoms in the framework of non-relativistic QED. We treat photo-ionization as a scattering process where in the remote past an atom in its ground state is targeted by one or several photons, while in the distant future the atom is ionized and the electron escapes to spacial infinity. Our main result shows that the ionization probability, to leading order in the fine-structure constant, $\alpha$, is correctly given by formal time-dependent perturbation theory, and, moreover, that the dipole approximation produces an error of only sub-leading order in $\alpha$. In this sense, the dipole approximation is rigorously justified.Comment: 25 page

CMS physics technical design report : Addendum on high density QCD with heavy ions

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