The implementation of a 2-core, multi-threaded itanium family processor

The design of the high end server processor code named Montecito incorporated several ambitious goals requiring innovation. The most obvious being the incorporation of two legacy cores on-die and at the same time reducing power by 23%. This is an effective 325% increase in MIPS per watt which necessitated a holistic focus on power reduction and management. The next challenge in the implementation was to ensure robust and high frequency circuit operation in the 90-nm process generation which brings with it higher leakage and greater variability. Achieving this goal required new methodologies for design, a greatly improved and tunable clock system and a better understanding of our power grid behavior all of which required new circuits and capabilities. The final aspect of circuit design improvement involved the I/O design for our legacy multi-drop system bus. To properly feed the two high frequency cores with memory bandwidth we needed to ensure frequency headroom in the operation of the bus. This was achieved through several innovations in controllability and tuning of the I/O buffers which are discussed as well.     

Inhibition of expression of the lysine-rich 30 kDa surface antigen of Entamoeba dispar by the transcription of its antisense RNA

The gene coding for the 30 kDa lysine rich surface antigen (Ed-Ag) that is present on membrane surfaces of Entamoeba dispar trophozoites has been characterized. A specific monoclonal antibody MAb 318-28 prepared against this antigen reacts with all E. dispar strains tested, but not with any of the antigens of E. histolytica. In order to understand the function of this antigen, we constructed two plasmids, pEdA-9 and pEdA-Rev, in which the antigen-coding sequence was introduced into the pEhAct-Neo shuttle vector in the direct and opposite orientation, respectively. When E. dispar trophozoites were transfected with pEdA-9, only a slight increase was observed in the expression of the antigen. However, when E. dispar trophozoites were transfected with pEdA-Rev, the expression of the native 30 kDa antigen was significantly inhibited. This inhibition was proportional to the level of resistance of the E. dispar culture to the neomycin derivative G418. Cytopathic assays detected only a slight difference between untransfected, pEdA-9 transfected and pEdA-Rev transfected trophozoites.     

Fair attribution of functional contribution in artificial and biological networks

This letter presents the multi-perturbation Shapley value analysis (MSA), an axiomatic, scalable, and rigorous method for deducing causal function localization from multiple perturbations data. The MSA, based on fundamental concepts from game theory, accurately quantifies the contributions of network elements and their interactions, overcoming several shortcomings of previous function localization approaches. Its successful operation is demonstrated in both the analysis of a neurophysiological model and of reversible deactivation data. The MSA has a wide range of potential applications, including the analysis of reversible deactivation experiments, neuronal laser ablations, and transcranial magnetic stimulation "virtual lesions," as well as in providing insight into the inner workings of computational models of neurophysiological systems.     

Controlled analysis of neurocontrollers with informational lesioning

How does one aim to understand neural information processing? One of the difficult first challenges is to identify the roles of the network's elements. To this end a functional contribution analysis (FCA) method has been developed and applied for studying the neurocontrollers of evolutionary autonomous agents (EAAs). The FCA processes data composed of multiple lesion experiments and the corresponding performance levels that the agent obtains under these lesions. It calculates the contribution values (CVs) of the network's elements such that the ability to predict the agent's performance under new, unseen lesions is maximized. Previous analysis has found a strong dependence of the CVs and the prediction error on the specific type of lesioning method used, i.e. on the way in which the activity of lesioned neurons is disrupted. We present a new, informational lesioning method (ILM), which views a lesion as a noisy channel and applies a controlled lesion to the network by varying the lesioning level from large to arbitrarily small magnitudes. Studying the ILM within the FCA framework, our main results are threefold: first, that lower lesioning levels permit more accurate FCA predictions; second, that the usage of minute ILM lesioning levels can uncover the long-term effects of elements on the network's functioning; and third, that as the lesioning level decreases, the CVs tend to approach limit values, reflecting the importance of these elements in the intact, normal-functioning neurocontroller.     

Circuits and techniques for high-resolution measurement of on-chip power supply noise

This paper presents a technique for characterizing the statistical properties and spectrum of power supply noise using only two on-chip low-throughput samplers. The samplers utilize a voltage-controlled oscillator to perform high-resolution analog-to-digital conversion with minimal hardware. The measurement system is implemented in a 0.13-/spl mu/m process along with a high-speed link transceiver. Measured results from this chip validate the accuracy of the measurement system and elucidate several aspects of power supply noise, including its cyclostationary nature.     

In vivo performances of pure Zn and Zn–Fe alloy as biodegradable implants

The disadvantage of current biodegradable metals such as Mg and Fe is the release of hydrogen gas in vivo that can cause gas embolism and the production of voluminous iron oxide that can cause inflammation, respectively. Such considerations have turned focus towards Zn as an alternative. This is based on the fact that Zn plays a crucial role in many physiological processes, as well as potentially being biocompatible and capable of with biodegradation. As such, the purpose of the present study was to evaluate the in vivo performance of pure Zinc and Zn–2%Fe implants. The use of iron as an alloying element was aimed at accelerating the corrosion rate of pure zinc by a micro-galvanic effect so as to maintain the post-implantation biodegradation characteristics of the implant. In vivo assessment was carried out using cylindrical disks implanted in the back midline of 16 male Wistar rats for up to 24 weeks. Post-implantation evaluation included monitoring the well-being of rats, weekly examination of hematological parameters: serum Zn levels, red and white blood cell counts and hemoglobin levels, X-ray radiography, histological analysis and corrosion rate assessment. The results obtained in terms of well-being, hematological tests and histological analysis of the rats indicate that the in vivo behavior of pure Zn and Zn–2%Fe implants was adequate and in line with the results obtained by the control group containing inert Ti–6Al–4V alloy implants. The corrosion rate of Zn–2%Fe alloy in in vivo conditions was relatively increased compared to pure Zn due to micro-galvanic corrosion.

Open image in new window

     

A low-cost Mr compatible ergometer to assess post-exercise phosphocreatine recovery kinetics

Objective

To develop a low-cost pedal ergometer compatible with ultrahigh (7 T) field MR systems to reliably quantify metabolic parameters in human lower leg muscle using phosphorus magnetic resonance spectroscopy.

Materials and methods

We constructed an MR compatible ergometer using commercially available materials and elastic bands that provide resistance to movement. We recruited ten healthy subjects (eight men and two women, mean age ± standard deviation: 32.8 ± 6.0 years, BMI: 24.1 ± 3.9 kg/m²). All subjects were scanned on a 7 T whole-body magnet. Each subject was scanned on two visits and performed a 90 s plantar flexion exercise at 40% maximum voluntary contraction during each scan. During the first visit, each subject performed the exercise twice in order for us to estimate the intra-exam repeatability, and once during the second visit in order to estimate the inter-exam repeatability of the time constant of phosphocreatine recovery kinetics. We assessed the intra and inter-exam reliability in terms of the within-subject coefficient of variation (CV).

Results

We acquired reliable measurements of PCr recovery kinetics with an intra- and inter-exam CV of 7.9% and 5.7%, respectively.

Conclusion

We constructed a low-cost pedal ergometer compatible with ultrahigh (7 T) field MR systems, which allowed us to quantify reliably PCr recovery kinetics in lower leg muscle using ³¹P-MRS.

     

The effects of processing variables on stress development in ultraviolet-cured coatings

A cantilever deflection technique was used to monitor stress development during ultraviolet photo-cure of acrylate coatings to the glassy state. Two coating systems were studied: a trifunctional monomer (trimethylol propane triacrylate, TMPTA) and a tetrafunctional monomer (pentaerythritol tetraacrylate, PETA). Both were photoinitiated with 2,2-dimethoxy-2-phenylacetophenone (DMPA). Average in-plane stresses of up to 30 MPa were measured upon curing at room temperature. The rate and magnitude of stress development rose with the photoinitiator concentration and with light intensity. Curing with more strongly absorbed light had similar effects. Light absorption caused decreased stress magnitudes in thicker coatings. Somewhat unexpectedly, the rate and magnitude of stress development increased with monomer functionality even though the conversion fell. Moreover, curing thick coatings with high radical concentrations (strongly absorbing light and large photoinitiator concentrations) caused ripple defects to form. With the appearance of these defects, stress ceased to rise with the photoinitiator concentration. Fourier transform infrared spectroscopy was employed to monitor conversion and to help understand these stress development trends. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1267–1277, 1997     

Ammonia synthesis enhanced by magnesium chloride absorption

Conversion to ammonia with Haber–Bosch catalysts can be increased above 95% by selective absorption of ammonia by MgCl₂. The maximum conversion depends on reaction and absorption equilibria. At very short times, the measured conversion rate is the same with and without absorption by the MgCl₂ salt; the overall rate constants are comparable to those in the literature. At larger times, conversion to ammonia can be over seven times greater with MgCl₂ than without. However, the overall rate constants can be over 10 times slower because they are controlled by ammonia diffusion in the solid salt. An approximate, pseudosteady state theory consistent with these results provides a strategy for improving the overall rate while keeping the conversion over 90%. For example, the absorption rates might be increased using smaller particles of absorbent on a porous inert absorbent support. The results provide part of the basis for designing small scale ammonia plants. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1364–1371, 2015     

Tell Me Who I Am: An Interactive Recommendation System

We consider a model of recommendation systems, where each member from a given set of players has a binary preference to each element in a given set of objects: intuitively, each player either likes or dislikes each object. However, the players do not know their preferences. To find his preference of an object, a player may probe it, but each probe incurs unit cost. The goal of the players is to learn their complete preference vector (approximately) while incurring minimal cost. This is possible if many players have similar preference vectors: such a set of players with similar “taste” may split the cost of probing all objects among them, and share the results of their probes by posting them on a public billboard. The problem is that players do not know a priori whose taste is close to theirs. In this paper we present a distributed randomized peer-to-peer algorithm in which each player outputs a vector which is close to the best possible approximation of the player’s real preference vector after a polylogarithmic number of rounds. The algorithm works under adversarial preferences. Previous algorithms either made severely limiting assumptions on the structure of the preference vectors, or had polynomial overhead. Research of N. Alon supported in part by the Israel Science Foundation and by the Von Neumann Fund. B. Awerbuch supported by NSF grants ANIR-0240551, CCF-0515080 and CCR-0311795. Research of Y. Azar supported in part by the German-Israeli Foundation and by the Israel Science Foundation. Research of B. Patt-Shamir supported in part by Israel Ministry of Science and Technology and by the Israel Science Foundation (grant 664/05).