Separable codes were defined by Cheng and Miao in 2011, motivated by applications to the identification of pirates in a multimedia setting. Combinatorially, t̅-separable codes lie somewhere between ...t-frameproof and (t - 1)-frameproof codes: all t-frameproof codes are t̅-separable, and all t̅-separable codes are (t - 1)-frameproof. Results for frameproof codes show that (when q is large) there are q-ary t̅-separable codes of length n with approximately q n/t codewords, and that no q-ary t̅-separable codes of length n can have more than approximately q n/(t-l) codewords. This paper provides improved probabilistic existence results for t-separable codes when t ≥ 3. More precisely, for all t ≥ 3 and all n ≥ 3, there exists a constant κ (depending only on t and n), such that there exists a q-ary t̅-separable code of length n with at least κq n/(t-1) codewords for all sufficiently large integers q. This shows, in particular, that the upper bound derived from the bound on (t - 1)-frameproof codes on the number of codewords in a t̅-separable code is realistic. The results above are more surprising after examining the situation when t = 2. Results due to Gao and Ge show that a q-ary 2̅-separable code of length n can contain at most 3/2q 2n/3 - 1/2q n/3 codewords, and that codes with at least κq 2n/3 codewords exist. Thus, optimal 2̅-separable codes behave neither like two-frameproof nor one-frameproof codes. This paper also observes that the bound of Gao and Ge can be strengthened to show that the number of codewords of a q-ary 2̅-separable code of length n is at most q 2n/3 + 1/2 q n/3 (q n/3 -1).
In 2010, Silva et al. studied certain classes of finite-field matrix channels in order to model random linear network coding where exactly t random errors are introduced. In this paper, we consider a ...generalization of these matrix channels where the number of errors is not required to be constant, indeed the number of errors may follow any distribution. We show that a capacity-achieving input distribution can always be taken to have a very restricted form (the distribution should be uniform given the rank of the input matrix). This result complements, and is inspired by a paper of Nobrega et al., which establishes a similar result for a class of matrix channels that model network coding with link erasures. Our result shows that the capacity of our channels can be expressed as maximization over probability distributions on the set of possible ranks of input matrices: a set of linear rather than exponential size.
Information is needed regarding the complex relationships between long-term functional outcomes and health-related quality of life (HRQoL) in Hirschsprung's Disease (HSCR). We describe long-term ...outcomes across multiple domains, completing a core outcome set through to adulthood.
HSCR patients operated at a single center over a 35-year period (1978–2013) were studied. Patients completed detailed questionnaires on bowel and urologic function, and HRQOL. Patients with learning disability (LD) were excluded. Outcomes were compared to normative data. Data are reported as median IQR or mean (SD).
186 patients (median age 28 18–32 years; 135 males) completed surveys. Bowel function was reduced (BFS 17 14–19 vs. 19 19–20, p < 0•0001;η2 = 0•22). Prevalence and severity of fecal soiling and fecal awareness improved with age (p < 0•05 for both). Urinary incontinence was more frequent than controls, most of all in 13–26y females (65% vs. 31%,p = 0•003). In adults, this correlated independently with constipation symptoms (OR 3.18 1.4–7.5,p = 0.008). HRQoL outcomes strongly correlated with functional outcome: 42% of children demonstrated clinically significant reductions in overall PedsQL score, and poor bowel outcome was strongly associated with impaired QOL (B = 22•7 12•7–32•7,p < 0•001). In adults, GIQLI scores were more often impacted in patients with extended segment disease. SF-36 scores were reduced relative to population level data in most domains, with large effect sizes noted for females in General Health (g = 1.19) and Social Wellbeing (g = 0.8).
Functional impairment is common after pull-through, but bowel function improves with age. Clustering of poor functional outcomes across multiple domains identifies a need for early recognition and long-term support for these patients.
Block‐avoiding point sequencings Blackburn, Simon R.; Etzion, Tuvi
Journal of combinatorial designs,
June 2021, 2021-06-00, 20210601, Letnik:
29, Številka:
6
Journal Article
Recenzirano
Odprti dostop
Let
n and
ℓ be positive integers. Recent papers by Kreher, Stinson, and Veitch have explored variants of the problem of ordering the points in a triple system (such as a Steiner triple system STS, ...directed triple system, or Mendelsohn triple system) on
n points so that no block occurs in a segment of
ℓ consecutive entries (thus the ordering is locally block‐avoiding). We describe a greedy algorithm which shows that such an ordering exists, provided that
n is sufficiently large when compared with
ℓ. This algorithm leads to improved bounds on the number of points in cases where this was known, but also extends the results to a significantly more general setting (which includes, e.g., orderings that avoid the blocks of a design). Similar results for a cyclic variant of this situation are also established. We construct STSs and quadruple systems where
ℓ can be large, showing that a bound of Stinson and Veitch is reasonable. Moreover, we generalize the Stinson–Veitch bound to a wider class of block designs and to the cyclic case. The results of Kreher, Stinson, and Veitch were originally inspired by results of Alspach, Kreher, and Pastine, who (motivated by zero‐sum avoiding sequences in abelian groups) were interested in orderings of points in a partial Steiner triple system where no segment is a union of disjoint blocks. Alspach et al. show that, when the system contains at most
k pairwise disjoint blocks, an ordering exists when the number of points is more than
15
k
−
5. By making use of a greedy approach, the paper improves this bound to
9
k
+
O(
k
2
∕
3
).
Immink and Weber recently defined and studied a channel with both gain and offset mismatch, modeling the behavior of charge-leakage in flash memory. They proposed a decoding measure for this channel ...based on minimizing Pearson distance (a notion from cluster analysis). This paper derives a formula for maximum likelihood decoding for this channel, and also defines and justifies a notion of minimum distance of a code in this context.
Pragmatists have traditionally been enemies of representationalism but friends of naturalism, when naturalism is understood to pertain to human subjects, in the sense of Hume and Nietzsche. In this ...volume Huw Price presents his distinctive version of this traditional combination, as delivered in his René Descartes Lectures at Tilburg University in 2008. Price contrasts his view with other contemporary forms of philosophical naturalism, comparing it with other pragmatist and neo-pragmatist views such as those of Robert Brandom and Simon Blackburn. Linking their different 'expressivist' programmes, Price argues for a radical global expressivism that combines key elements from both. With Paul Horwich and Michael Williams, Brandom and Blackburn respond to Price in new essays. Price replies in the closing essay, emphasising links between his views and those of Wilfrid Sellars. The volume will be of great interest to advanced students of philosophy of language and metaphysics.
Anatomy and physiology of the peritoneum Blackburn, Simon C., MBBS, BSc (Hons), MEd, FRCS (Paed Surg); Stanton, Michael P., MBBS, MD, FRCS (Paed Surg)
Seminars in pediatric surgery,
12/2014, Letnik:
23, Številka:
6
Journal Article
Recenzirano
Abstract The peritoneum is commonly encountered in abdominal surgery. The development and rotation of the primitive gut tube lead to the normal adult arrangement of the peritoneal cavity, which forms ...bloodless planes allowing the retroperitoneal portions of the bowel to be safely mobilised. The arrangement of the peritoneum also forms spaces in which infected fluid or pus can collect. The microcirculation of peritoneal fluid is now well understood, and the large absorptive surface of the peritoneum can be exploited in peritoneal dialysis. The absorption of gas by the peritoneum following abdominal surgery is faster in neonates than in older children, and understanding this process contributes to the interpretation of post-operative radiographs.
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