Photolysis of phenol derivatives

On irradiation di-p-t-butylphenyl carbonate has been shown to rearrange via a novel photo-catalysed double Fries reaction to yield 5,5-di-t-buty1-2,2'-dihydroxybenzophenone. The nsubstituted phenyl carbonate gave rise to 2,2,-dihydroxy and 2,4,-dihydroxybenzophonone. An indication that the mechanism of the reaction involved the formation and eventual rearrangement of the corresponding salicylate was obtained by isolation of 5-t-butylsalicylie acid and by the irradiation of phenyl salioylate. The photolysis of aryl formate esters has indicated that the primary decomposition process may well be intramolecular extrusion of carbon monoxide although there is some evidence that other dissociation processes are in operation. The irradiation of ?-naphthyls phenylp p-t-butylphenyl, 2,6-xyly1 and p-chloro-phenyl formates in oyolohexene gave rise to the corresponded; aryl cyclohevl ether. This photooatalysed addition to an olefin is not restricted to cyclohexene and irradiation of p-t-butylphenyl formate in pant-2-one and 2-methylpent-l-one gave rise to the respective ethers. Attempts were made to elucidate the mechanism by irradiation of 2-aIly1-4-t-butylphenyl formate and 2-(3,3-dimethylallyl)phenol. Both irradiations gave rise to good yields of the normal addition products. Another route to the generation of aryloxy radicals was investigated involving the synthesis and decomposition of peroxy compounds containing phonoxy ether groups. The synthesis and decomposition of Bis-phenoxypropionyl)peroxide has been carried out showing the generation of phenoxyethyl radicals. 0,0-t-Buty1-o-phenylmonopercarbonate has been synthesised and analysis of the mixture obtained from its decomposition in cyclohexene has shown the presence of phenyl cyciohoxyl ether. Methyl and ethyl 5-phenoxypenta-2,4-dienoate were synthesized, the former by condensation of phenol with methyl but-l-on-3-yne-1-oarboxylate, the latter by reuotion of carbethony-methylene-triphenyl aosphorane and 3-phenozyacrolein. Attempts to synthesise this system by reaction of 3-phonoxyacrolein with several compounds having an active methylene group were unsuccessful. Diels-Alder reactions were carried out on the ethyl ester to give l-ethyl 2v5-dimethylbenzeno-12v3-tricarboxylate with dimethylacetylenedicar.boxylate7 ethyl 1-naphthoate 171th benzyne and 3-oarbethoxy-6-phenoxy-1,2,6-tetrahydrophthalic anhydride and the corresponding acid with maleic allydride. Ethyl 2-methy1-5-phenoxypenta-204-dienoateg synthesised by reaction of 3-phenoxyacrolein and 1-carbethoxyethylidene-triphenyl phosphorane did not react with the above dienophiles

Economic Evaluations Alongside Efficient Study Designs Using Large Observational Datasets: the PLEASANT Trial Case Study

BACKGROUND: Large observational datasets such as Clinical Practice Research Datalink (CPRD) provide opportunities to conduct clinical studies and economic evaluations with efficient designs. OBJECTIVES: Our objectives were to report the economic evaluation methodology for a cluster randomised controlled trial (RCT) of a UK NHS-delivered public health intervention for children with asthma that was evaluated using CPRD and describe the impact of this methodology on results. METHODS: CPRD identified eligible patients using predefined asthma diagnostic codes and captured 1-year pre- and post-intervention healthcare contacts (August 2012 to July 2014). Quality-adjusted life-years (QALYs) 4 months post-intervention were estimated by assigning utility values to exacerbation-related contacts; a systematic review identified these utility values because preference-based outcome measures were not collected. Bootstrapped costs were evaluated 12 months post-intervention, both with 1-year regression-based baseline adjustment (BA) and without BA (observed). RESULTS: Of 12,179 patients recruited, 8190 (intervention 3641; control 4549) were evaluated in the primary analysis, which included patients who received the protocol-defined intervention and for whom CPRD data were available. The intervention's per-patient incremental QALY loss was 0.00017 (bias-corrected and accelerated 95% confidence intervals [BCa 95% CI] -0.00051 to 0.00018) and cost savings were £14.74 (observed; BCa 95% CI -75.86 to 45.19) or £36.07 (BA; BCa 95% CI -77.11 to 9.67), respectively. The probability of cost savings was much higher when accounting for BA versus observed costs due to baseline cost differences between trial arms (96.3 vs. 67.3%, respectively). CONCLUSION: Economic evaluations using data from a large observational database without any primary data collection is feasible, informative and potentially efficient. Clinical Trials Registration Number: ISRCTN03000938

Duel and sweep algorithm for order-preserving pattern matching

Given a text $T$ and a pattern $P$ over alphabet $\Sigma$, the classic exact matching problem searches for all occurrences of pattern $P$ in text $T$. Unlike exact matching problem, order-preserving pattern matching (OPPM) considers the relative order of elements, rather than their real values. In this paper, we propose an efficient algorithm for OPPM problem using the "duel-and-sweep" paradigm. Our algorithm runs in $O(n + m\log m)$ time in general and $O(n + m)$ time under an assumption that the characters in a string can be sorted in linear time with respect to the string size. We also perform experiments and show that our algorithm is faster that KMP-based algorithm. Last, we introduce the two-dimensional order preserved pattern matching and give a duel and sweep algorithm that runs in $O(n^2)$ time for duel stage and $O(n^2 m)$ time for sweeping time with $O(m^3)$ preprocessing time.Comment: 13 pages, 5 figure

Open-label, cluster randomised controlled trial and economic evaluation of a brief letter from a GP on unscheduled medical contacts associated with the start of the school year: the PLEASANT trial

BACKGROUND: Asthma is seasonal with peaks in exacerbation rates in school-age children associated with the return to school following the summer vacation. A drop in prescription collection in August is associated with an increase in the number of unscheduled contacts after the school return. OBJECTIVE: To assess whether a public health intervention delivered in general practice reduced unscheduled medical contacts in children with asthma. DESIGN: Cluster randomised trial with trial-based economic evaluation. Randomisation was at general practice level, stratified by size of practice. The intervention group received a letter from their general practitioner (GP) in late July outlining the importance of (re)taking asthma medication before the return to school. The control group was usual care. SETTING: General practices in England and Wales. PARTICIPANTS: 12 179 school-age children in 142 general practices (70 randomised to intervention). MAIN OUTCOME: Proportion of children aged 5-16 years who had an unscheduled contact in September. Secondary endpoints included collection of prescriptions in August and medical contacts over 12 months (September-August). Economic endpoints were quality-adjusted life-years gained and health service costs. RESULTS: There was no evidence of effect (OR 1.09; 95% CI 0.96 to 1.25 against treatment) on unscheduled contacts in September. The intervention increased the proportion of children collecting a prescription in August by 4% (OR 1.43; 95% CI 1.24 to 1.64). The intervention also reduced the total number of medical contacts between September-August by 5% (incidence ratio 0.95; 95% CI 0.91 to 0.99).The mean reduction in medical contacts informed the health economics analyses. The intervention was estimated to save £36.07 per patient, with a high probability (96.3%) of being cost-saving. CONCLUSIONS: The intervention succeeded in increasing children collecting prescriptions. It did not reduce unscheduled care in September (the primary outcome), but in the year following the intervention, it reduced the total number of medical contacts. TRIAL REGISTRATION NUMBER: ISRCTN03000938; Results

The influence of aryl-aryl interactions in the photochemistry of some 1,3-Diarylpropanes

The irradiation of 1,3-diarylpropanols in acidic methanol results in their conversion to the corresponding methyl ethers. This reaction and that of the photodechlorination of some 1,3-diarylpropanes is influenced by the presence of electron donating substituents in the aryl group remote from the reactive site

Bit-parallel search algorithms for long patterns

Peer reviewe

Efficient exact pattern-matching in proteomic sequences

This paper proposes a novel algorithm for complete exact pattern-matching focusing the specificities of protein sequences (alphabet of 20 symbols) but, also highly efficient considering larger alphabets. The searching strategy uses large search windows allowing multiple alignments per iteration. A new filtering heuristic, named compatibility rule, contributed decisively to the efficiency improvement. The new algorithm’s performance is, on average, superior in comparison with its best-rated competitors

Algorithms in the Ultra-Wide Word Model

The effective use of parallel computing resources to speed up algorithms in current multi-core parallel architectures remains a difficult challenge, with ease of programming playing a key role in the eventual success of various parallel architectures. In this paper we consider an alternative view of parallelism in the form of an ultra-wide word processor. We introduce the Ultra-Wide Word architecture and model, an extension of the word-RAM model that allows for constant time operations on thousands of bits in parallel. Word parallelism as exploited by the word-RAM model does not suffer from the more difficult aspects of parallel programming, namely synchronization and concurrency. For the standard word-RAM algorithms, the speedups obtained are moderate, as they are limited by the word size. We argue that a large class of word-RAM algorithms can be implemented in the Ultra-Wide Word model, obtaining speedups comparable to multi-threaded computations while keeping the simplicity of programming of the sequential RAM model. We show that this is the case by describing implementations of Ultra-Wide Word algorithms for dynamic programming and string searching. In addition, we show that the Ultra-Wide Word model can be used to implement a nonstandard memory architecture, which enables the sidestepping of lower bounds of important data structure problems such as priority queues and dynamic prefix sums. While similar ideas about operating on large words have been mentioned before in the context of multimedia processors [Thorup 2003], it is only recently that an architecture like the one we propose has become feasible and that details can be worked out.Comment: 28 pages, 5 figures; minor change