了解嵌入系统的引导技术

引导是指在接通电源和装入应用之间,系统完成的一系列步骤,它在理论上简单,但实际上经常很复杂。引导加载器的主要任务是装入操作系统,但软硬件工程师对这个过程的看法并不相同。     

Towards elucidating the connection between epithelial–mesenchymal transitions and stemness

Epithelial cells undergoing epithelial-to-mesenchymal transitions have often been shown to behave as cancer stem cells, but the precise molecular connection remains elusive. At the genetic level, stemness is governed by LIN28/let-7 double inhibition switch, whereas EMT/MET is controlled by miR-200/ZEB double inhibition circuit and LIN28 is inhibited by miR-200, coupling the two modules. Here, using a specially devised theoretical framework to investigate the dynamics of the LIN28/let-7 system, we show that it can operate as a three-way switch (between low, high and intermediate LIN28 levels termed the D, U and hybrid D/U states) similar to the three-way operation of the miR-200/ZEB circuit that allows for the existence of a hybrid epithelial/mesenchymal (E/M) phenotype. We find significant correspondence between the existence of the three states of the two circuits: E–D, M–U and E/M–D/U. Incorporating the activation of OCT4 by LIN28, we find that the hybrid E/M phenotype has high likelihood (when compared with either the E or M states) to gain stemness. Combining the LIN28/let-7 regulation by NF-κB and c-MYC, we find that NF-κB, but not c-MYC, elevates the likelihood of E/M phenotype to gain stemness. Our results are consistent with emerging concept that partial EMT can lead to stemness.     

Switching in structural, optical, and magnetic properties of self-assembled Co-doped ZnO: effect of Co-concentration

Here, we report on the self-assembled Co-doped ZnO nanoparticles synthesized by using sol–gel technique. It has been observed that when Co is introduced in the solution, nanoparticles arrange themselves into a particular pattern. This self-assembly of Zn_1?xCo_xO, were found to be consistent with the change in Co-doping concentration. Using electron microscopy these systems were studied to confirm the assembly formation with doping. Optical study of these assemblies suggests the decrease in direct band gap of these systems with the increase in doping concentration. In addition to it, the Urbach energy was found to be increased, indicating the redistribution of states in between conduction and valence band with doping. Magnetic measurement shows the introduction of paramagnetic behavior with Co-doping in this self-assembled Co-doped ZnO.     

Measurement of Ambient Ammonia over the National Capital Region of Delhi,India

Mixing ratio of ambient ammonia (NH₃) was measured at various locations of the National Capital Region (NCR) of Delhi, India using a NH₃-analyzer during January 2010 to June 2012 in campaign mode. The present study has been carried out on campaign based measurement of mixing ratios of NH₃ and NO _x for short period of time over the NCR of Delhi represent the indicative values over the region. The average mixing ratio of ambient NH₃ was 20.9 ± 1.6 ppb during the period. The maximum average mixing ratio of ambient NH₃ (28.8 ± 3.0 ppb) was recorded in an industrial area surrounded by intensive vehicular traffic followed by an agricultural farm (27.5 ± 2.1 ppb), whereas the minimum (6.4 ± 1.2 ppb) was recorded in the semi-urban area. The diurnal trend of NH₃ depended on the ambient temperature at most of the sites and was affected by wind direction. Ambient NH₃ was correlated with the NO _x mixing ratio suggesting that the vehicular emission may be one of the sources of ambient NH₃ in the NCR of Delhi. However, long-term measurements of ambient NH₃ and their precursors will lead to seasonal variation of source apportionment over the NCR, Delhi, India.     

Binding of basic fibroblast growth factor to fibrinogen and fibrin

Fibrin is formed at sites of tissue injury and provides the temporary matrix needed to support the initial endothelial cell responses needed for vessel repair. Basic fibroblast growth factor (bFGF) also acts at sites of injury and stimulates similar vascular cell responses. We have, therefore, investigated whether there are specific interactions between bFGF and fibrinogen and fibrin that could play a role in coordinating these actions. Binding studies were performed using bFGF immobilized on Sepharose beads and soluble 125I-labeled fibrinogen and also using Sepharose-immobilized fibrinogen and soluble 125I-bFGF. Both systems demonstrated specific and saturable binding. Scatchard analysis indicated two classes of binding sites for each with Kd values of 1.3 and 260 nM using immobilized bFGF; and Kd values of 0.9 and 70 nM using immobilized fibrinogen. After conversion of Sepharose-immobilized fibrinogen to fibrin by treatment with thrombin, bFGF also demonstrated specific and saturable binding with two classes of binding sites having Kd values of 0.13 and 83 nM. Fibrin binding was also investigated by clotting a solution of bFGF and fibrinogen, and two classes of binding sites were demonstrated using this system with Kd values of 0.8 and 261 nM. The maximum molar binding ratios of bFGF to fibrinogen were between 2.0 and 4.0 with the four binding systems. We conclude that bFGF binds specifically and saturably to fibrinogen and fibrin with high affinity, and this may have implications regarding the localization of its effect at sites of tissue injury.     

Serial and parallel algorithms for the medial axis transform

An O(n²) time serial algorithm is developed for obtaining the medial axis transform (MAT) of an n×n image. An O(log n) time CREW PRAM algorithm and an O(log² n) time SIMD hypercube parallel algorithm for the MAT are also developed. Both of these use O(n²) processors. Two problems associated with the MAT, the area and perimeter reporting problem, are studied. An O(log n) time hypercube algorithm is developed for both of them, where n is the number of squares in the MAT, and the algorithms use O(n²) processors     

High-T c superconductors: New insights from angle-resolved photoemission

Recent angle-resolved photoemission (ARPES) studies of the high-T _c superconductors by the Argonne group are briefly reviewed. First we discuss sum rules to establish a spectral function interpretation of the data, and the use of ARPES to obtain the momentum distribution. We then apply these ideas to the normal and superconducting state spectra for B₂Sr₂Cu₂O₈. Among the topics discussed are the Fermi surface, polarization selection rules, bilayer splitting, and the superconducting gap.     

Effect of iron (Wt.%) on adhesive wear response of Al-12Si-1Cu-0.1Mg alloy in dry sliding conditions

The presence of iron leads to different types of intermetallics in Al-Si alloys, among them needle shaped β-phase (Al₅FeSi) can lead to variations in hardness of the Al-Si alloy which ultimately can affect the wear resistance of the alloy. In this paper, the effect of iron on wear behavior of cast Al-Si alloys has been reported. Sliding wear behavior of eutectic alloy Al-12Si-1Cu-0.1Mg was investigated in dry sliding conditions by using pin-on-disk test configuration against heat treated EN31 steel counter-surface at room temperature. Sliding wear behavior has been evaluated at four normal loads of 5, 20, 50 and 70 N and two sliding speeds, 2 m/s and 4 m/s. Worn pin surfaces were examined by scanning electron microscopy (SEM) for analyzing wear mechanisms. The wear mechanism has been found to be mild oxidative type at lower sliding speed of 2m/s for entire range of loads used in the study. Transition to severe metallic wear occurs at higher sliding speed of 4 m/s at normal load of 5 N. Hardness of the alloy increased with increase in iron addition primarily due to presence of needle shaped Fe-rich intermetallics but it leads to an increased wear rate.     

Significance of fruit and vegetable allergens: Possibilities of its reduction through processing

Fruit and vegetable allergies are prevalent commonly in adults, infants, and children all around the world, but more importantly in Europe and North America. The only solution is complete abstinence from the responsible food, which can be very difficult due to their presence in the form of hidden or undeclared ingredients. Various studies have shown the direct effect of processing on the secondary structure of proteins that can mitigate the allergic properties. The impact of these processing techniques on fruit and vegetable allergies have shown limited success due to the fact that they have multiple allergens that are especially heat stable. Apples, kiwi, peach, and melons are common fruits, whereas celery and carrot are the common vegetables that can result in allergic reactions for some portion of the population upon exposure.

Abbreviations: IgE: immunoglobulin E, OAS: oral allergy syndrome, nsLTP: nonspecific lipid transfer proteins, LTP: lipid transfer proteins, HPP: high-pressure processing, PEF: pulsed electric field, CD: circular dichroism, pI: isoelectric point, DBPCFCs: double-blind placebo-controlled food challenges