{RePair} Grammars Are the Smallest Grammars for Fibonacci Words

Grammar-based compression is a loss-less data compression scheme that represents a given string w by a context-free grammar that generates only w. While computing the smallest grammar which generates a given string w is NP-hard in general, a number of polynomial-time grammar-based compressors which work well in practice have been proposed. RePair, proposed by Larsson and Moffat in 1999, is a grammar-based compressor which recursively replaces all possible occurrences of a most frequently occurring bigrams in the string. Since there can be multiple choices of the most frequent bigrams to replace, different implementations of RePair can result in different grammars. In this paper, we show that the smallest grammars generating the Fibonacci words F_k can be completely characterized by RePair, where F_k denotes the k-th Fibonacci word. Namely, all grammars for F_k generated by any implementation of RePair are the smallest grammars for F_k, and no other grammars can be the smallest for F_k. To the best of our knowledge, Fibonacci words are the first non-trivial infinite family of strings for which RePair is optimal

Linear-Time Text Compression by Longest-First Substitution

We consider grammar-based text compression with longest first substitution (LFS), where non-overlapping occurrences of a longest repeating factor of the input text are replaced by a new non-terminal symbol. We present the first linear-time algorithm for LFS. Our algorithm employs a new data structure called sparse lazy suffix trees. We also deal with a more sophisticated version of LFS, called LFS2, that allows better compression. The first linear-time algorithm for LFS2 is also presented

Life-threatening Hyperkalemia during a Combined Therapy with the Angiotensin Receptor Blocker Candesartan and Spironolactone

We describe a hypertensive nephrosclerosis patient presenting with severehyperkalemia due to a combination therapy of the angiotensin receptor blocker (ARB)candesartan and spironolactone despite mildly decreased renal function. Recently,ARBs are replacing the ACE inhibitors. The combined therapy with ARB andspironolactone will eventually become the standard regimen. The strict attention andclose monitoring of serum potassium should be mandatory in combination therapy toprevent hyperkalemia. Assessment of trans-tubular potassium gradient (TTKG) andfractional excretion of potassium (FEK) before starting the therapy would help inidentifying the patients at higher risk of developing hyperkalemia. Co-administrationof thiazide or loop diuretics is recommended to reduce the risk of hyperkalemia

Dialysis Therapies Effects of the Creation of Arteriovenous Fistula for Hemodialysis on Cardiac Function and Natriuretic Peptide Levels in CRF

• Background: Cardiac failure occasionally is caused by the creation of vascular access for hemodialysis. However, the influence of an arteriovenous (AV) fistula on cardiac function has not been fully elucidated. The present study investigated serial changes in cardiac function and hormonal levels after the AV fistula operation. Methods: Sixteen patients with chronic renal failure underwent echocardiographic studies before and 3, 7, and 14 days after the AV fistula operation. Plasma atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) concentrations were measured before and 1, 3, 6, 10, and 14 days after the operation. Results: Creation of an AV fistula produced significant elevations in left ventricular (LV) end-diastolic diameter (؉4%), fractional shortening (؉8%), and cardiac output (CO; ؉15%). In LV inflow velocities measured by Doppler echocardiography, deceleration time of the early diastolic filling wave shortened (؊12%) and the ratio of the peak velocity of early diastolic to atrial filling (E-A ratio) increased (؉18%). The difference in duration of LV inflow and pulmonary venous flow at atrial contraction, a marker of LV end-diastolic pressure, significantly shortened day 14 after the operation (؊37%). That is, creation of an AV fistula induced LV diastolic dysfunction toward a restrictive filling pattern. Both ANP and BNP levels increased after the operation, and maximal percentages of increase were observed after 10 days (ANP, ؉48%; BNP, ؉68%). In the relationship between cardiac function and hormonal response, the increase in CO was associated with elevation of ANP levels (r ‫؍‬ 0.61; P ‫؍‬ 0.01), but not BNP levels. Conversely, the increase in E-A ratio correlated only with BNP level elevation (r ‫؍‬ 0.60; P ‫؍‬ 0.01). Conclusion: Our observations indicate that creation of an AV fistula has significant effects on cardiac systolic and diastolic performance, and ANP release is induced by volume loading, but BNP release is stimulated by LV diastolic dysfunction. Am J Kidney Dis 40:974-982

Additional file 2 of PMEL p.Leu18del dilutes coat color of Kumamoto sub-breed of Japanese Brown cattle

Additional file 2: Fig. S1. PMEL p.Leu18del is responsible for coat color dilution in Kumamoto sub-breed of Japanese Brown cattle

Additional file 1 of PMEL p.Leu18del dilutes coat color of Kumamoto sub-breed of Japanese Brown cattle

Additional file 1: Table S1. DNA polymorphisms in coat color-related genes identified by whole genome sequencing. Table S2. Number of animals used in each experiment