Repeat Transanal Advancement Flap Repair: Impact on the Overall Healing Rate of High Transsphincteric Fistulas and on Fecal Continence

PURPOSE: Transanal advancement flap repair (TAFR) has been advocated as the treatment of choice for transsphincteric fistulas passing through the upper or middle third of the external anal sphincter. It is not clear whether previous attempts at repair adversely affect the outcome of TAFR. The purpose of the present study was to evaluate the success rate of a repeat TAFR and to assess the impact of such a second procedure on the overall healing rate of high transsphincteric fistulas and on fecal continence. METHODS: Between January 2001 and January 2005, a consecutive series of 87 patients (62 males; median age, 49 (range, 27-73) years) underwent TAFR. Median follow-up was 15 (range, 2-50) months. Patients in whom the initial operation failed were offered two further treatment options: a second flap repair or a long-term indwelling seton drainage. Twenty-six patients (male:female ratio, 5:2; median age, 51 (range, 31-72) years) preferred a repeat repair. Continence status was evaluated before and after the procedures by using the Rockwood Faecal Incontinence Severity Index (RFISI). RESULTS: The healing rate after the first TAFR was 67 percent. Of the 29 patients in whom the initial procedure failed, 26 underwent a repeat TAFR. The healing rate after this second procedure was 69 percent, resulting in an overall success rate of 90 percent. Both before and after the first attempt of TAFR, the median RFISI was 7 (range, 0-34). In patients who underwent a second TAFR, the median RFISI before and after this procedure was 9 (range, 0-34) and 8 (range, 0-34), respectively. None of these changes were statistically significant. CONCLUSIONS: Repeat TAFR increases the overall healing rate of high transsphincteric fistulas from 67 percent after one attempt to 90 percent after two attempts without a deteriorating effect on fecal continence

Past, present and future mathematical models for buildings (i)

This is the first of two articles presenting a detailed review of the historical evolution of mathematical models applied in the development of building technology, including conventional buildings and intelligent buildings. After presenting the technical differences between conventional and intelligent buildings, this article reviews the existing mathematical models, the abstract levels of these models, and their links to the literature for intelligent buildings. The advantages and limitations of the applied mathematical models are identified and the models are classified in terms of their application range and goal. We then describe how the early mathematical models, mainly physical models applied to conventional buildings, have faced new challenges for the design and management of intelligent buildings and led to the use of models which offer more flexibility to better cope with various uncertainties. In contrast with the early modelling techniques, model approaches adopted in neural networks, expert systems, fuzzy logic and genetic models provide a promising method to accommodate these complications as intelligent buildings now need integrated technologies which involve solving complex, multi-objective and integrated decision problems

Past, present and future mathematical models for buildings (ii)

This article is the second part of a review of the historical evolution of mathematical models applied in the development of building technology. The first part described the current state of the art and contrasted various models with regard to the applications to conventional buildings and intelligent buildings. It concluded that mathematical techniques adopted in neural networks, expert systems, fuzzy logic and genetic models, that can be used to address model uncertainty, are well suited for modelling intelligent buildings. Despite the progress, the possible future development of intelligent buildings based on the current trends implies some potential limitations of these models. This paper attempts to uncover the fundamental limitations inherent in these models and provides some insights into future modelling directions, with special focus on the techniques of semiotics and chaos. Finally, by demonstrating an example of an intelligent building system with the mathematical models that have been developed for such a system, this review addresses the influences of mathematical models as a potential aid in developing intelligent buildings and perhaps even more advanced buildings for the future

Transfer function method of calculating cooling loads, heat extraction and space temperature

A new cooling load calculation procedure, the transfer function method, has been incorporated in the 1972 ASHRAE HANDBOOK OF FUNDAMENTALS. This article presents a short discussion of the calculation procedure based on the transfer function method, and demonstrates the extended capability of this new, computer-oriented, method.Une nouvelle m\ue9thode de calcul de l'effort de refroidissement, la m\ue9thode de fonction de transfert, a \ue9t\ue9 introduite dans l'\ue9dition de 1972 du Handbook of Fundamentals. Le pr\ue9sent article est une br\ue8ve \ue9tude des modalit\ue9s de calcul de cette m\ue9thode, mais il s'agit surtout de montrer que celle-ci poss\ue8de un champ d'application plus vaste que l'"ancienne" m\ue9thode. On compare l'"ancienne" m\ue9 thode et la m\ue9thode \ue9largie quant au calcul des profils d' effort de refroidissement. Les r\ue9sultats d'un calcul-\ue9 chantillon montrent graphiquement les applications \ue9largies de cette m\ue9thode relativement \ue0 un programme d'exploitation variable, au calcul de l'enl\ue8vement de la chaleur \ue0 une temp\ue9 rature ambiante variable de l'air et aux caract\ue9ristiques d' enl\ue8vement de la chaleur d'une borne de conditionnement de l' air (y compris les organes de commande).Peer reviewed: NoNRC publication: Ye

Cooling load caused by lights

An analytical study of the cooling load resulting from power input to lights indicated the need for an experimental determination of some of the parameters involved in the calculations of this load. To meet this need a full scale calorimeter room was built and instrumented by the Division of Building Research of the National Research Council of Canada. This paper presents the results of a series of tests that were carried out using this facility to measure the cooling load for fluorescent lights both with and without air flow through the fixtures, and a set of design coefficients for a range of light fixtures, ventilation rates, and room heat storage capacities. The results of these tests confirm the conclusions reached by the analytical study, namely, that the relation between a step change in power input to lights and the corresponding cooling load component can be described by an exponential type of expression with two independent coefficients. One of them depends on the room heat storage capacity and the other is a function of the way the room ventilation system is arranged and the type of light fixtures that are installed.Une \ue9tude analytique de la charge thermique d\ue9gag\ue9e par des luminaires nous a indiqu\ue9 la n\ue9cessit\ue9 d'une d\ue9termination exp\ue9rimentale de certains param\ue8tres intervenant dans le calcul de cette charge de refroidissement. Pour r\ue9pondre \ue0 ce besoin, une chambre calorim\ue9trique \ue0 pleine \ue9chelle a \ue9t\ue9 construite et \ue9quip\ue9e par la Division de la recherche du b\ue2timent du Conseil National de Recherches du Canada. Cet article expose les r\ue9sultats d'une s\ue9rie de tests effectu\ue9s dans cette chambre, dans le but de d\ue9terminer la charge de refroidissement caus\ue9e par des luminaires fluorescents. Les conditions d'essais ont \ue9t\ue9 multiples et comprennent des effets tels que: l'\ue9coulement ou le non-\ue9coulement d'air \ue0 travers des fixations, les coefficients de projet valables pour une gamme de fixations des luminaires, de taux de ventilation et de capacit\ue9s thermiques de la chambre. Les r\ue9sulats de ces tests conduisent \ue0 la confirmation des conclusions de l'\ue9tude analytique et notamment, au fait que la relation entre une variation \ue9chelon de la puissance lumineuse et la charge thermique de refroidissement correspondante, peut s'exprimer par une expression du type exponentielle avec deux coefficients ind\ue9pendants. Un de ces coefficients d\ue9pend de la capacit\ue9 thermique de la chambre et l'autre est une fonction de la facon dont est arrang\ue9 le syst\ue8me de ventilation et du type de fixation des luminaires.Peer reviewed: NoNRC publication: Ye

Relation Between Thermal Resistance and Heat Storage in Building Enclosures

The annual building heating/energy requirement is a function of the thermal resistance of the building enclosure and, to a lesser extent, of the mass of the building envelope. In this Note relations that can be used to estimate the "trade- off" between the mass and the thermal resistance of the building enclosure are presented in graphical form. These relations define the permitted allowances for mass in terms of reduction in thermal resistance as given in the proposed Canadian Code for Energy Conservation in New Buildings.Les besoins thermiques \ue9nerg\ue9tiques annuels d'un b\ue2timent sont fonction de la r\ue9sistance thermique de l'enceinte du b\ue2timent et, \ue0 un degr\ue9moindre, de la masse de l'enveloppe du b\ue2timent. L'auteur pr\ue9sente, sous forme graphique, les relations qui peuvent servir \ue0 \ue9valuer le "compromis" entre la masse et la r\ue9sistance thermique de l'enceinte du b\ue2timent. Ces relations d\ue9finissent les tol\ue9rances de masse en termes de r\ue9duction de la r\ue9sistance thermique telles que donn\ue9es dans le code canadien pour l'\ue9conomie et l'\ue9nergie dans les nouveaux \ue9difices (\ue0 l'\ue9tat de projet).Aussi Disponible en Fran\ue7ais: Relation entre la r\ue9 sistance thermique et l'emmagasinage de la chaleur dans les enveloppes de b\ue2timentPeer reviewed: NoNRC publication: Ye

Calculation of below-grade residential heat loss: low-rise residential building

A simple calculation makes it possible to determine the maximum rate of below-grade heat loss from a basement and the total heat loss over the heating season. The procedure accounts for the variation of below-grade heat loss during the year. This is a significant factor in the house heat balance. Analytical as well as experimental data are used to develop a set of factors that are then used in the calculation of below-grade heat loss. This note is a revised and extended version of an ASHRAE paper [NRCC No. 20416]. This revision extends the full basement calculation procedure to include slab-on-grade and shallow basement heat loss calculations.Un calcul simple permet de d\ue9terminer le taux maximum de perte de chaleur d'un sousbassement au-dessous du niveau du sol, ainsi que la perte de chaleur totale au cours de la p\ue9riode de chauffe. Cette m\ue9thode tient compte de la variation de la perte de chaleur au-dessous du niveau du sol pendant l'ann\ue9e. Il s'agit l\ue0 d'un important facteur dans le bilan thermique de la maison. L'auteur se sert de donn\ue9es analytiques et exp\ue9rimentales pour d\ue9finir une s\ue9rie de facteurs qui servent ensuite au calcul de la perte de chaleur au-dessous du niveau du sol. Cette note est une version revue et augment\ue9e d'un document de l'ASHRAE (CNRC no. 20416). La m\ue9thode de calcul applicable aux sous-sols complets y est \ue9tendue aux soubassements \ue0 dalle \ue0 niveau de sol et aux soubassements de faible hauteur.Peer reviewed: YesNRC publication: Ye

Calculating cooling load caused by lights

A method of computing cooling load from lights, based upon analysis of power input to lights, is presented, and experimental confirmation through use of a calorimetric facility is described. Design data are given in tabular form, and can be used in conjunction with the new transfer function method published in 1972 ASHRAE HANDBOOK OF FUNDAMENTALS.Une \ue9tude analytique de la charge de refroidissement due \ue0 l' alimentation des lumi\ue8res en \ue9lectricit\ue9 a montr\ue9 la n\ue9 cessit\ue9 d'une d\ue9termination exp\ue9rimentale de quelques-un des facteurs servant \ue0 calculer la charge de refroidissement. Une pi\ue8ce calorim\ue9trique de grandeur naturelle (10 x 14 x 13 pieds, d'\ue9tage \ue0 \ue9tage) a \ue9t\ue9 construite et munie d' instruments \ue0 cette fin. Les r\ue9sultats des essais confirment ceux de l'\ue9tude analytique, \ue0 savoir que le rapport entre le changement progressif de l'alimentation en \ue9 lectricit\ue9 et l'augmentation subs\ue9quente de chaleur dans la pi\ue8ce peut \ueatre exprim\ue9 sous forme exponentielle. Les r\ue9 sultats exp\ue9rimentaux sont d'une utilit\ue9 restreinte pour ce qui est du calcul des plans, puisqu'ils n'englobent pas de nombreux mod\ue8les de pi\ue8ces, appareils d'\ue9clairage, genres d' installations et syst\ue8mes de ventilation. Toutefois, les r\ue9 sultats exp\ue9rimentaux ont permis d'obtenir un ensemble de donn\ue9es servant \ue0 calculer la charge de refroidissement d' une pi\ue8ce due \ue0 l'\ue9clairage. Le pr\ue9sent article pr\ue9sente ces donn\ue9es.Peer reviewed: NoNRC publication: Ye

An assessment of common assumptions in estimating cooling loads and space temperatures

This paper describes the results of an analytical study to determine the errors involved in using a linear methematical model to calculate with sufficient accuracy the elements of an air-conditioning installation; the purpose of the study is also to evaluate the effect of the architectural characteristics of a building on its cooling load. It is felt that a linear mathematical model, with the help of a digital computer, would predict cooling loads for air conditioning at reasonable cost. The linear mathematical model is based primarily on the assumption that convection and radiation heat transfer is directly proportional to the respective temperature differences. The calculations reveal that the cooling load is not closely related to the heat transfer coefficients of the surfaces. The results indicate that the mathematical model using a combined heat transfer coefficient for inside surfaces does not accurately represent the room thermal balance; in calculating the cooling load, similar elements in the room can be considered as a unit forming part of its envelope; in addition, lightweight room elements must be accounted for.Le pr\ue9sent article expose les r\ue9sultats d'une \ue9tude analytique visant \ue0 d\ue9terminer les erreurs d\ue9coulant de l' utilisation d'un mod\ue8le math\ue9matique lin\ue9aire pour calculer avec une pr\ue9cision suffisante les \ue9l\ue9ments d'une installation de climatisation; l'\ue9tude a \ue9galement pour but d'\ue9valuer l'effet des caract\ue9ristiques architecturales des locaux sur leur charge frigorique. On croit qu'un mod\ue8le math\ue9matique lin\ue9aire permettrait, \ue0 l'aide d'un ordinateur num\ue9rique, de pr\ue9voir \ue0 un co\ufbt raisonnable quelle seraient ls charges frigoriques de climatimath\ue9matique lin\ue9aire est fond\ue9 principalement sur l'hypoth\ue9se voulant que la transmission de chaleur par convection et par rayonnement soit directement proportionnelle aux diff\ue9rences de temp\ue9 ratures respectives. Les calculs r\ue9v\ue8lent que la charge frigorique n'est pas intimement li\ue9e aux coefficients de transmission calorique des surfaces. Les r\ue9sultats montrent que le mod\ue8le math\ue9matique, utilisant un coefficient global de transmission calorique par les surfaces int\ue9rieures, ne repr\ue9sente pas exactement le bilan thermique de la pi\ue8ce; lors du calcul de la charge frigorique, on peut consid\ue9rer que dans la pi\ue8ce les \ue9l\ue9ments similaires constituent un tout, partie de son enceinte; il importe \ue9galement de tenir compte des \ue9l\ue9ments constitutifs l\ue9gers de celle-ci.Peer reviewed: NoNRC publication: Ye