A 6 GHz 68 mW BiCMOS phase-locked loop

The design of a 6 GHz fully monolithic phase-locked loop fabricated in a 1 μm, 20 GHz BiCMOS technology is described. The circuit incorporates a voltage-controlled oscillator that senses and combines the transitions in a ring oscillator to achieve a period equal to two ECL gate delays. A mixer topology is also used that exhibits full symmetry with respect to its inputs and operates with supply voltages as low as 1.5 V. Dissipating 60 mW from a 2 V supply, the circuit has a tracking range of 300 MHz, an rms jitter of 3.1 ps, and phase noise of -75 dBc/Hz at 1 kHz offset     

Transluminal balloon angioplasty, stents, and atherectomy

Arterial bypass grafting for occlusive disease is still considered the gold standard in the treatment of arterial occlusive disease. However, less invasive methods are available for select patients. Percutaneous balloon angioplasty has been shown to be effective in focal iliac artery stenosis, with patency rates of 50% to 90% at 5 years. Patency rates for femoropopliteal lesions are generally less than 50% at 2 years. Complications seen with balloon angioplasty often can be treated with arterial stents. Stents can be categorized into balloon-expandable, which provide a rigid scaffold to support the artery, self-expanding, which exert radial force to resist external compression, and thermal expanding stents, which allow for the use of a smaller introducer sheath. Another treatment option is atherectomy, in which the offending lesion is removed instead of fracturing and dilating the lumen. Although overall initial results of atherectomy have not been favorable, short lesions with eccentric atheroma or intimal hyperplasia, such as those seen in dialysis access fistulas or vein graft stenoses, may respond well.     

Function of yeast Rad52 protein as a mediator between replication protein A and the Rad51 recombinase

The RAD51 and RAD52 genes of Saccharomyces cerevisiae are key members of the RAD52 epistasis group required for genetic recombination and the repair of DNA double-stranded breaks. The RAD51 encoded product mediates the DNA strand exchange reaction. Efficient strand exchange is contingent upon the addition of the heterotrimeric single-stranded DNA binding factor replication protein A (RPA) after Rad51 has nucleated onto the single-stranded DNA. However, if the single-stranded DNA is incubated with Rad51 and RPA simultaneously to mimic what may be expected to occur in vivo, the efficiency of strand exchange decreases dramatically, revealing an inhibitory effect of RPA that is distinct from its stimulatory function. Interestingly, the inclusion of Rad52 protein, which has been purified in this study from yeast cells, restores the efficiency of strand exchange. Thus, Rad52 functions as a co-factor for the Rad51 recombinase, acting specifically to overcome the apparent competition by RPA for binding to single-stranded DNA.     

A linear minimum mean square error multiuser receiver inRayleigh-fading channels

We generalize the multiuser (CDMA spread spectrum) communication systems to the fading environments. We first extend Verdu's (1986) conventional optimum receiver to Rayleigh-fading environments and then evaluate its performance. Having no knowledge of the received power at the receiving end, we therefore need an estimator to efficiently estimate the received signal strength of each user in fading environments. A linear minimum mean square error (LMMSE) unbiased estimator is proposed to attain this goal. By using the minimum mean square error (MMSE) Bayesian estimation, we further propose the LMMSE bit estimator for efficient demodulation. Its performance is close to the optimum multiuser receiver but with a much simpler polynomial complexity. To further reduce the complexity, we extend the LMMSE estimator to the sequential LMMSE estimator. In sequential estimation, we do not need to implement the matched filter banks and to perform the matrix inversion when estimating. In addition, it converges after approximately 2k iterations, where k is the number of users. With this fast convergence property and the simple structure, the sequential LMMSE estimator provides an attractive alternative to the implementation of a multiuser system     

Phase transformation of calcia-alumina-magnesia fibres produced by inviscid melt spinning

CaO-Al₂O₃-MgO (CAM) ceramic fibre produced via inviscid melt spinning (IMS) was investigated for phase transformation. Differential thermal analysis (DTA) on the as-spun CAM fibre gave two transformation peaks, one for exothermic peak at around 927°C and the other for endothermic one at around 1100°C. In order to identify each phase transformation x-ray diffraction (XRD) analysis was performed on the CAM fibres heat-treated to each phase transformation completion temperature. The exothermic peak was determined to represent crystallization of remaining amorphous phase in the as-spun CAM fibre. The endothermic peak was determined to correspond to transformation of non-equilibrium CaO · Al₂O₃ phase to equilibrium 3CaO· 5Al₂O₃ phase.     

Cryptanalysis of an involutional block cipher using cellular automata

In 2006, an involutional block cipher using cellular automata was proposed. A self-invertible CA-based structure allows for an efficient hardware implementation. This paper analyzes the insecurity of the cipher due to its conjugate property. The results of this study will make it possible to construct a decryption process without knowledge of the secret key.     

Microstructure of aragonite grown at an air–liquid interface

Aragonite particles dispersed in a bioresorbable polymer matrix are considered to be a good candidate for bone prosthesis materials. It is important to characterize the microstructure of synthetic aragonite used for biomedical applications, since the microstructure may influence its integration, resorption and replacement by bone. We studied late stages of aragonite growth, at an air–liquid interface, from a solution not doped with additives. Comparison was made between the types of synthetic aragonite microstructure and that of aragonite which is found in nature (mollusc shells, gallstones, Earth's crust). The microstructure of natural aragonite is unique to certain classes of living organisms and the understanding of its structure/function relationships may help to select the types of synthetic aragonite for specific biomedical applications. Three types of synthetic aragonite were observed based on grain size and grain morphology. This revised version was published online in November 2006 with corrections to the Cover Date.     

Pharmacologic profile of survivors of acute myocardial infarction at United States academic hospitals

Optimal drug therapy for patients with acute myocardial infarction (AMI) is well described in the medical literature. However, data on the actual pharmacologic management of patients surviving AMI at academic hospitals is unavailable. The purpose of this study was to document treatment profiles in 500 patients surviving AMI at 12 academic hospitals in the United States. These profiles were compared with established guidelines and were evaluated for trends. Overall, thrombolytics (streptokinase > or = tissue-type plasminogen activator) were administered in 29% of the patients, with a greater proportion of patients receiving beta-blockers than calcium channel antagonists in the initial 72 hours (61% vs 40%; p < 0.005) and at discharge (51% vs 35%; p < 0.005). Further, women were less likely than men to receive thrombolytic therapy (odds ratio [OR] = 0.61; confidence interval [CI], 0.54 to 0.69) or beta-blocker therapy within the first 72 hours (OR = 0.61; CI, 0.55 to 0.67) or at hospital discharge (OR = 0.53; CI, 0.48 to 0.58). Overall, improvements could still be made in the number of patients who receive thrombolytic and acute and chronic beta-blocker therapies after AMI, particularly in women. Changes in treatment profiles may be a reflection of the publication of large clinical trials.     

An elementary proof of Sylvester’s double sums for subresultants

In 1853 Sylvester stated and proved an elegant formula that expresses the polynomial subresultants in terms of the roots of the input polynomials. Sylvester’s formula was also recently proved by Lascoux and Pragacz using multi-Schur functions and divided differences. In this paper, we provide an elementary proof that uses only basic properties of matrix multiplication and Vandermonde determinants.     

AC hot-carrier effects in MOSFETs with furnaceN2O-nitrided gate oxides

AC hot-carrier effects in n-MOSFETs with thin (~85 Å) N₂O-nitrided gate oxides have been studied and compared with control devices with gate oxides grown in O₂. Results show that furnace N₂O-nitrided oxide devices exhibit significantly reduced AC-stress-induced degradation. In addition, they show weaker dependences of device degradation on applied gate pulse frequency and pulse width. Results suggest that the improved AC-hot-carrier immunity of the N₂O-nitrided oxide device may be due to the significantly suppressed interface state generation and neutral electron trap generation during stressing