New building code for 1970.
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Fire creates a complex toxic environment involving flame, heat, oxygen depletion, smoke, and toxic gases. The nature of that environment is dependent upon not only the materials present but on the fire event, that is, the fire scenario. Materials have different toxic gas profiles under different conditions; therefore, toxic fire gas generation is not intrinsic to any one material. Large fires in buildings constitute a severe toxic threat regardless of the materials being burned. In the past, building codes in the United States included the phrase, "no more toxic than wood," in reference to fire gases from building materials. Such phrases have recently been deleted, because of the lack of either an accepted definition or test methodology to assess toxicity. While several states have attempted regulatory activity, the most recent approach (taken by the state of New York) has been the establishment of a data bank on toxic potency of building and furnishing materials. The utility of such a data bank without available hazard analysis methodology is open to discussion, since toxic potency data are not directly applicable to toxic hazard assessment. A number of small-scale animal exposure tests have been developed to assess the potency of the toxic combustion products from combustible materials. Criticism of these tests relates to the relevance of the combustion module (a smoke generation apparatus) and the appropriateness of the animal model, particularly for irritant gases. Recent data from more than 2000 fire fatality cases and carbon monoxide exposure cases are discussed in this paper to help put small-scale laboratory test results into perspective. Toxicity is only one of the several fire properties related to materials. All fire parameters are interrelated, that is, they are not independent variables. Thus, predicting the toxicity of burning materials is a problem without a comprehensive solution. Measures have been taken, however, to reduce the number of fires and to reduce fire severity.
Montgomery County, Maryland was the first major jurisdiction to pass a law requiring smoke detectors in all homes. Smoke detector coverage in the county was evaluated five years after the law's implementation and compared to the coverage in neighboring Fairfax County, Virginia, which has no such law. Firefighters visited 651 randomly selected owner-occupied homes and tested each detector. While a similar percentage of homes in Montgomery and Fairfax counties complied with detector codes (42 per cent vs 44 per cent, respectively), Montgomery County had a significantly lower percentage of homes with no working detectors (17 per cent vs 30 per cent) and with no detectors at all (6 per cent vs 16 per cent). In general, Montgomery County residents complied with what they believed the law required, but lacked knowledge of the law's details. New homes where building codes required detectors and homes where owners assumed that detectors were required by law were likely to have working detectors. Analyses of 12 years of fire data suggest that as a county approaches complete detector coverage, the risk of residential fire deaths decreases. An essentially unenforced law seems to be obeyed because it conforms to community values.
This paper addresses itself to the solutions developed in Massachusetts to three key legal problem areas with regard to the psychiatric halfway house. The areas are (1) the assurance of the overall quality of the programs through rigorous implementation of regulatory statutes; (2) the determination of beneficial location and equitable geographical distribution of these facilities as enabled through local zoning ordinances--preventing at the same time arbitrary community exclusion; and (3) the establishment of standards for safe, suitable, and feasible structures to house the community residence as determined by building codes.
The jurisdictional responsibility for natural radioactivity in Canada is divided between the federal and provincial governments. The desire for uniform standards has resulted in the formation of a scientific group to advise governments concerning the desirability of standards for exposure to natural radioactivity. The various types of exposure are reviewed with emphasis on naturally occurring radon in homes. The scientific Committee could not agree either philosophically or practically on the control level for radon in homes. To resolve this impasse, it undertook a calculation designed to illustrate for Canada, the potential cancers saved each year compared to the actual lung cancer rate, with an estimate of the cost for each limit derived. A second calculation reviewed the cost of modifying the building code and estimated the long term effect by comparing avoided cancers and cost. The calculations are based on cross-Canada surveys, intensive long term investigation of smaller groups of homes and national housing statistics. The results are discussed and serve to illustrate development of the proposed policy.
Injuries resulting from falls from heights still constitute a significant portion of urban trauma. At this pediatric trauma center, 70 children were admitted from 1985 to 1988 after sustaining a fall of 10 feet or greater or at least one story. The mean patient age was 5 years and 68% of the patients were boys. Seventy-eight percent of falls occurred from 2 stories or less and usually took place at or near the home. Most patients sustained a single major injury and all survived. The majority of injuries involved the head or skeleton and residual functional deficits were uncommon. The incidence of falls from heights has remained high in urban areas despite public education and building codes that require window guards and safety rails.
The physical environment of a treatment program affects patient outcome, but how and to what degree is not known. However, decisions about the design of the environment must be made, and they must be made in the face of cost and building-code constraints and widely varying patient characteristics and treatment models. The authors describe the design principles and philosophies they followed in the remodeling of an in-patient treatment and research service in a university psychiatric hospital and indicate where cost and code constraints resulted in a less than ideal solution. They point out that many apparent amenities, such as a ward kitchen, are significant milieu therapy resources, and they advocate the involvement of all levels of staff in the planning process.
Radon 222 and its radioactive decay products can enter buildings and, through inhalation, expose the inhabitants' pulmonary tissues to ionizing radiation. Studies of radon levels in the United States indicate that variations of 100-fold or greater exist among private dwellings. In one region, 55% of homes had levels exceeding 4 pCi/L (0.15 Bq/L), which is the guidance level recommended by the US Environmental Protection Agency. Ventilation and tightness of construction are important determinants of radon levels. In some instances, fans or heat exchangers can reduce excessive concentrations, but in others more elaborate remedial measures may be required. Physicians may obtain information about radon through Environmental Protection Agency regional offices and state radiation control programs. The risk of radiogenic cancer is believed to increase with exposure to ionizing radiation. According to some estimates, concentrations of radon decay products in US homes could be responsible for several thousand cases of lung cancer per year. Studies of radon levels in representative buildings and guidelines are needed to ensure safe, effective, and cost-effective countermeasures. Architects, contractors, designers, building code administrators, health physicists, and biomedical investigators can help with solutions.
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The studies presented in this article investigate the memory processes that underlie two phenomena in threshold identification: word superiority over pseudowords and the repetition effect (a prior presentation of an item facilitates later identification of that item). Codification (i.e., the development of a single memory code that can be triggered even by fragmented input information) explains the faster and more accurate identification of words than pseudowords. Our studies trace the development and retention of such codes for repeated pseudowords and examine the growth and loss of the repetition effect for both pseudowords and words. After approximately five prior occurrences, words and pseudowords are identified equally accurately in two types of threshold identification tasks, suggesting codification has been completed for pseudowords. Although the initial word advantage disappears, the accuracy of identification still increases with repetitions. The facilitation caused by repetition is not affected much by spacing within a session, but drops from one day to the next, and after a delay of one year has disappeared (new and old words were identified equally well). These results suggest an episodic basis for the repetition effect. Most important, after one year, performance is equal for old pseudowords and new and old words: all these levels are superior to that for new pseudowords, suggesting that the learned codes for pseudowords are as strong and permanent as the codes for words. A model of identification is presented in which feedback from codes and episodic images in memory facilitates letter processing. An instantiation of the model accounts for the major features of the data.
The coding sequence for the 97-amino-acid-residue-long immunoglobulin heavy-chain variable (VH) regions of the mouse apparently arose as repeats of the two short building blocks. Three of the recognizable copies of the one 21-base-long prototype sequence A-C-T-G-G-A-T-A-T-G-A-C-C-T-G-G-A-G-T-G-G are invariably found to occupy the fixed positions within the 5' half of each VH coding sequence. Interestingly, the first and third copies specify the relatively invariant regions represented by the 7th to 13th and 41st to 47th amino acid residues (the first and second framework regions), whereas the second copy specifies the first hypervariable region (31st to 35th amino acid residues). These copies maintain at least 57.2% (12 out of 21) base sequence homology to the above-noted prototype building block. Base sequences of the other 14- to 15-base-long prototype building block differ from each other by as much as 60% between individual VHS. Yet one of its copies invariably occupies the terminal region of each VH coding sequence, thus specifying the very invariant third framework region. Other copies occupy unfixed positions in the VH and its attendant hydrophobic leader coding sequence as well as in adjacent noncoding sequences. The homology thus revealed between the VH coding sequence and its adjacent noncoding sequences suggests their concordant evolution.
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Histones play a fundamental role in eukaryotic organisms not only as scaffolding proteins in DNA packaging but also in regulating gene expression. They constitute the protein reel around which DNA wraps forming nucleosomes. This initial packing gives rise to the chromatin fiber which is next folded into three-dimensional arrangements. Additionally, histones have expanded their functions through the emergence of histone variants which have specialized purposes and can deeply affect chromatin organization and dynamics. Moreover, both canonical histones and histone variants comprise the building blocks of the histone code by being targets of different post-translational modifications (PTMs) that occur in a highly regulated manner both in place and time. Most of the above-mentioned about chromatin organization is conserved among eukaryotes. However, trypanosomatid histones have many peculiarities that entail a special description. In this review, we compile the current knowledge of canonical core histones, histone variants, and their PTMs in trypanosomatids. We highlight the similarities and differences between histone variants and their canonical counterparts in trypanosomatids, and we compare them with those from model organisms. Finally, we discuss the crosstalk between different histone marks and their genomic distribution underlying the uniqueness of trypanosomatids.