A 0.5-V all-digital clock-deskew buffer with I/Q phase outputs

This paper proposes a low supply voltage all-digital clock-deskew buffer with in-phase and quadrature phase (I/Q) outputs on an intra-chip. In some application-specific integrated chips or silicon intellectual properties might enter hibernation mode to conserve energy. The long locking time induces a large standby current, which results in greater power consumption. Furthermore, I/Q clock signals are widely adopted in the communication systems and double data rate memories. The proposed all-digital clock-deskew buffer can operate from 220 to 570 MHz at 0.5 V and the power consumption is 1.95 mW at 570 MHz. This buffer can also supply a quadrature phase output using a proposed two-step edge detector.     

Kähler submanifolds of the symmetrized polydisc

This paper proves the non-existence of common Kähler submanifolds of the complex Euclidean space and of the symmetrized polydisc endowed with their canonical metrics.     

Microwave-assisted multicomponent reaction of aryl amidines: regiospecific synthesis of new polysubstituted thiopyrano-, and pyrano[4,3-d]pyrimidines

A series of new functionalized thiopyrano-, pyrano[4,3-d]pyrimidine derivatives with benzyl group residing in 8-position of fused pyrimidine nucleus were synthesized through multicomponent reactions of aromatic aldehydes, tetrahydrothiopyran-4-one(tetrahydropyran-4-one), and aryl amidines using t-BuOK as a base under microwave heating. The procedure is facile, avoiding time-consuming and costly syntheses, tedious work-up, and purifications of precursors as well as protection/deprotection of functional groups. This method is very efficient due to short reaction times and easy work up and provides a four-component strategy for the construction of the thiopyrano-, and pyrano[4,3-d] pyrimidine skeletons.     

An efficient and facile synthesis of inhibitors for hepatitis C viral and anti-SARS agents: 4-aryl-5-cyano-1,6-dihydro-2-thiouracils

One-pot, multicomponent reaction for the synthesis of 4-aryl-5-cyano-1,6-dihydro-2-thiouracils via three-component from aromatic aldehydes, ethyl 2-cyanoacetate and S-benzylisothiourea hydrochloride (methyl carbamimidothioate sulfate) under methanol is described. These compounds have many drug activities, such as anti-hepatitis C viral, anti-Severe acute respiratory syndrome and anti-HIV-1 integrese activity. The advantages of this procedure include the short reaction time, mild reaction conditions and excellent yields.     

Analysis of Data with Censored Initiating and Terminating Times: A Missing-Data Approach

Survival data with censored initiating and terminating times have surfaced in some recent epidemiologic studies. Unlike standard survival analysis with known initiating times, analysis of data with both censored initiating and terminating times requires maximization of a complicated bivariate likelihood, which is often difficult to carry out. This article considers a missing-data formulation of the problem and focuses on the use of EM-type algorithms to simplify the computation of maximum likelihood estimates. This approach provides a feasible way of performing regression analysis with such bivariate survival data. Several illustrative examples are provided, including a real-data analysis application involving a cohort of HIV-infected hemophiliac patients.     

Copper‐Catalyzed Formal [2+2+1] Heteroannulation of Alkenes,Alkylnitriles, and Water: Method Development and Application to a Total Synthesis of (±)‐Sacidumlignan D

A copper‐catalyzed three‐component reaction of alkenes, alkylnitriles, and water affords γ‐butyrolactones in good yields. The domino process involves an unprecedented hydroxy‐cyanoalkylation of alkenes and subsequent lactonization with the creation of three chemical bonds and a quaternary carbon center. The synthetic potential of this novel [2+2+1] heteroannulation reaction was illustrated by a concise total synthesis of (±)‐sacidumlignan D.