Cost-Efficient Decimal Adder Design in Quantum-dot Cellular Automata

Applications that cannot tolerate the loss of accuracy that results from binary arithmetic demand hardware decimal arithmetic designs. Binary arithmetic in Quantum-dot cellular automata (QCA) technology has been extensively investigated in recent years. However, only limited attention has been paid to QCA decimal arithmetic. In this paper, two cost-efficient binary-coded decimal (BCD) adders are presented. One is based on the carry flow adder (CFA) using a conventional correction method. The other uses the carry look ahead (CLA) algorithm which is the first QCA CLA decimal adder proposed to date. Compared with previous designs, both decimal adders achieve better performance in terms of latency and overall cost. The proposed CFA-based BCD adder has the smallest area with the least number of cells. The proposed CLA-based BCD adder is the fastest with an increase in speed of over 60% when compared with the previous fastest decimal QCA adder. It also has the lowest overall cost with a reduction of over 90% when compared with the previous most cost-efficient design.

Limbal stem cell deficiency and ocular phenotype in ectrodactyly-ectodermal dysplasia-clefting syndrome caused by p63 mutations

Objective: To describe the ocular phenotype in patients with ectrodactyly-ectodermal dysplasia-clefting (EEC) syndrome (MIM#604292) and to determine the pathogenic basis of visual morbidity. Design: Retrospective case series. Participants: Nineteen families (23 patients) affected by EEC syndrome from the United Kingdom, Ireland, and Italy. Methods: General medical examination to fulfill the diagnostic criteria for EEC syndrome and determine the phenotypic severity. Mutational analysis of p63 was performed by polymerase chain reaction-based bidirectional Sanger sequencing. All patients with EEC syndrome underwent a complete ophthalmic examination and ocular surface assessment. Limbal stem cell deficiency (LSCD) was diagnosed clinically on the basis of corneal conjunctivalization and anatomy of the limbal palisades of Vogt. Impression cytology using immunofluorescent antibodies was performed in 1 individual. Histologic and immunohistochemical analyses were performed on a corneal button and corneal pannus from 2 EEC patients. Main Outcome Measures: The EEC syndrome phenotypic severity (EEC score), best-corrected Snellen visual acuity (decimal fraction), slit-lamp biomicroscopy, tear function index, tear breakup time, LSCD, p63 DNA sequence variants, impression cytology, and corneal histopathology. Results: Eleven heterozygous missense mutations in the DNA binding domain of p63 were identified in all patients with EEC syndrome. All patients had ocular involvement and the commonest was an anomaly of the meibomian glands and lacrimal drainage system defects. The major cause of visual morbidity was progressive LSCD, which was detected in 61% (14/23). Limbal stem cell deficiency was related to advancing age and caused a progressive keratopathy, resulting in a dense vascularized corneal pannus, and eventually leading to visual impairment. Histologic analysis and impression cytology confirmed LSCD. Conclusions: Heterozygous p63 mutations cause the EEC syndrome and result in visual impairment owing to progressive LSCD. There was no relationship of limbal stem cell failure with the severity of EEC syndrome, as classified by the EEC score, or the underlying molecular defect in p63. Financial Disclosure(s): The authors have no proprietary or commercial interest in any of the materials discussed in this article. © 2012 American Academy of Ophthalmology.

Metabolic-activity of pathogenic bacteria during semicontinuous anaerobic-digestion

In natural environments such as anaerobic digesters, bacteria are frequently subjected to the stress of nutrient fluxes because of the continual changes in the flow of nutrients, and to survive, they must be capable of adapting readily to nutrient changes. In this study, the metabolic activities of Escherichia coli, Salmonella typhimurium, Yersinia enterocolitica, Listeria monocytogenes, and Campylobacter jejuni were studied within culture bags (Versapor-200 filters, 0.22-mu m pore size) in laboratory anaerobic digesters. The metabolic activity of these bacteria was indicated by their adenylate energy charge (EC) ratios and their ability to incorporate [H-3]thymidine, which was related to the respective changes in viable numbers within the culture bags during anaerobic digestion. Fluctuations in the adenylate EC ratios, the uptake of [H-3]thymidine, and the viable numbers of E. coli, S. typhimurium, Y. enterocolitica, and L. monocytogenes cells were probably due to constant changes in the amount of available nutrients within the anaerobic digesters. The viability of S. typhimurium increased quickly after a fresh supply of nutrients was added to the system as indicated by the uptake of [H-3]thymidine and an increase in the adenylate EC ratios. The viable numbers of E. coli, S. typhimurium, Y. enterocolitica, and L. monocytogenes organisms declined rapidly from 10(7) to 10(8) CFU/ml to 10(3) to 10(4) CFU/ml and remained at this level for an indefinite period. The decimal reduction time calculated during the period of exponential decline ranged from 0.8 to 1.2 days for these bacteria. C. jejuni had the greatest mean decimal reduction time value (3.6 days). This bacterium had adenylate EC ratios of less than 0.5 during anaerobic digestion, although the adenylate nucleotide concentrations in the cells were much greater than those in the other enteric cells. The results show that the enteric bacteria investigated probably exist in transient states between different stages of growth because of fluctuating nutrient levels during anaerobic digestion.

Lifetime visual prognosis of patients with glaucoma

BACKGROUND: To investigate the visual outcome of glaucoma patients.

DESIGN: This is a retrospective study of case notes of patients who died while under follow up in a glaucoma clinic of a University Hospital in Scotland between 2006 and 2009.

PARTICIPANTS: Seventy-seven patients were identified.

METHODS: Data collected included type of glaucoma, coexisting pathology and best-corrected visual acuity in Snellen (converted to decimal values) for the first and final clinic visit. The final visual status was evaluated based on the best-corrected visual acuity of the better seeing eye at the last glaucoma clinic visit. Patients who had best-corrected visual acuity of less than Snellen decimal 0.5 were considered not to meet the standards for driving.

MAIN OUTCOME MEASURES: Snellen decimal best-corrected visual acuity, fulfilment of driving standards, and eligibility for partial sight and blind registration at the last clinic visit.

RESULTS: The mean ages at presentation and death were 71.8 ± 10.3 years and 82.2 ± 8.7 years respectively. The mean Snellen decimal best-corrected visual acuity of the better eye at presentation was 0.78, and at the final clinic visit was 0.61. At the final clinic visit, no patients were partial sight registrable, four (5.2%) were blind registrable, and 27 (35.1%) did not fulfil UK driving criteria. Glaucoma patients with other ocular pathologies were more likely to fail UK driving criteria at presentation (P = 0.02) and at last clinic visit (P = 0.03).

CONCLUSION: The majority of glaucoma patients maintained good visual function at the end of their lifetime.

Change of visual acuity recording methods in clinical studies across the years

Purpose: To report any differences in the visual acuity (VA) recording method used in peer-reviewed ophthalmology clinical studies over the past decade. Methods: We reviewed the method of assessing and reporting VA in 160 clinical studies from 2 UK and 2 US peer-reviewed journals, published in 1994 and 2004. Results: The method used to assess VA was specified in 62.5% of UK-published and 60% of US-published papers. In the results sections of the UK publications the VA measurements presented were Snellen acuity (n = 58), logMAR acuity (n = 20) and symbol acuity (n = 1). Similarly in the US publications the VA was recorded in the results section using Snellen acuity (n = 60) and logMAR acuity (n = 14). Overall 10% of the authors appeared to convert Snellen acuity measurements to logMAR format. Five studies (3%) chose to express Snellen-type acuities in decimal form, a method which can easily lead to confusion given the increased use of logMAR scoring systems. Conclusion: The authors recommend that to ensure comparable visual results between studies and different study populations it would be useful if clinical scientists worked to standardized VA testing protocols and reported results in a manner consistent with the way in which they are measured. Copyright © 2008 S. Karger AG.