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Valuing IT through Virtual Process Measurement
 In Procs. 15 th ICIS Intl’ Conference, ACM
, 1994
"... The so called "productivity paradox " associated with information technology remains the focus of active research in information systems. One explanation involves the dearth of useful measures to assess the value of IT investments. A review of the predominant approaches to such measurement ..."
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The so called "productivity paradox " associated with information technology remains the focus of active research in information systems. One explanation involves the dearth of useful measures to assess the value of IT investments. A review of the predominant approaches to such measurement reveals a number of serious weaknesses and fundamental limitations. The research described in this paper addresses these limitations through a complementary methodology termed virtual process measurement (VPM). Through VPM, assessments of IT value are determined through the measurement of computerbased process representations (i.e., virtually), as opposed to measuring their real counterparts in ongoing organizations � this approach a ords a number of advantages that are unattainable through extant techniques. In this paper, the VPM methodology is discussed in considerable detail, and examples from industry practice are used to demonstrate the use and utility of this approach. The paper closes with a set of conclusions and some possible directions for continued research.
Asymptotic efficiency and finitesample properties of the generalized profiling estimation of . . .
, 2009
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Strategies for Preparing Computer Science Students for the Multicore World
"... Multicore computers have become standard, and the number of cores per computer is rising rapidly. How does the new demand for understanding of parallel computing impact computer science education? In this paper, we examine several aspects of this question: (i) What parallelism body of knowledge do t ..."
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Multicore computers have become standard, and the number of cores per computer is rising rapidly. How does the new demand for understanding of parallel computing impact computer science education? In this paper, we examine several aspects of this question: (i) What parallelism body of knowledge do today’s students need to learn? (ii) How might these concepts and practices be incorporated into the computer science curriculum? (iii) What resources will support computer science educators, including nonspecialists, to teach parallel computing? (iv) What systemic obstacles impede this change, and how might they be overcome? We address these concerns as an initial framework for responding to the urgent challenge of injecting parallelism into computer science curricula.
Peptide secondary structure folding reaction coordinate: Correlation between uv raman amide iii frequency, psi ramachandran angle, and hydrogen bonding
 J. Phys. Chem. B
, 2006
"... We used UV resonance Raman (UVRR) spectroscopy to quantitatively correlate the peptide bond AmIII 3 frequency to its Ψ Ramachandran angle and to the number and types of amide hydrogen bonds at different temperatures. This information allows us to develop a family of relationships to directly estima ..."
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We used UV resonance Raman (UVRR) spectroscopy to quantitatively correlate the peptide bond AmIII 3 frequency to its Ψ Ramachandran angle and to the number and types of amide hydrogen bonds at different temperatures. This information allows us to develop a family of relationships to directly estimate the Ψ Ramachandran angle from measured UVRR AmIII 3 frequencies for peptide bonds (PBs) with known hydrogen bonding (HB). These relationships ignore the more modest Φ Ramachandran angle dependence and allow determination of the Ψ angle with a standard error of (8°, if the HB state of a PB is known. This is normally the case if a known secondary structure motif is studied. Further, if the HB state of a PB in water is unknown, the extreme alterations in such a state could additionally bias the Ψ angle by (6°. The resulting ability to measure Ψ spectroscopically will enable new incisive protein conformational studies, especially in the field of protein folding. This is because any attempt to understand reaction mechanisms requires elucidation of the relevant reaction coordinate(s). The Ψ angle is precisely the reaction coordinate that determines secondary structure changes. As shown elsewhere (Mikhonin et al. J. Am. Chem. Soc. 2005, 127, 7712), this correlation can be used to determine portions of the energy landscape along the Ψ reaction coordinate. Introduction The various techniques of molecular spectroscopy constitute the toolset used by scientists for investigating molecular conformations and reaction mechanisms. These various spectroscopic techniques require quantitative correlations between the spectral parameters measured and the molecular conformational parameters. NMR and especially multidimensional NMR techniques are certainly the most powerful spectroscopic methods for solution studies. 1928 J. Phys. Chem. B 2006, 110, 19281943 10 by C R D. We are optimistic that these relationships will be very useful for protein conformational studies, especially in the field of protein folding. This is because any attempt to understand reaction mechanisms, such as, for example, protein folding, requires elucidation of the relevant reaction coordinate(s). The Ψ angle is precisely the reaction coordinate that determines secondary structure changes. As shown elsewhere 60 the correlation we propose can be used to experimentally determine features of the energy landscape along this Ψ reaction coordinate. Such an experimental insight into a protein conformation and energy landscape is crucially needed, since there are still a lot of unresolved questions regarding the theoretical modeling of protein folding despite remarkable recent achievments. As described elsewhere, 43 the 21residue alaninebased peptide AAAAA(AAARA) 3 A (AP) was prepared (HPLC pure) at the Pittsburgh Peptide Facility by using the solidstate peptide synthesis method. The AP solutions in water contained 1 mg/ mL concentrations of AP, and 0.2 M concentrations of sodium perchlorate, which was used as an internal intensity and frequency standard. UV Resonance Raman Instrumentation. The Raman instrumentation has been described in detail elsewhere. Results and Discussion Dependence of AmIII 3 Frequency on Ramachandran Angles and Hydrogen Bonding. The amide III (AmIII) band region is complex. We recently examined this spectral region in detail and identified a band, which we call AmIII 3 and which is most sensitive to the peptide bond conformation. Peptide Secondary Structure Folding Reaction Coordinate J. Phys. Chem. B, Vol. 110, No. 4, 2006 1929 gives rise to strong NH to C R H bend coupling. In contrast, for Rhelixlike Ψ and Φ Ramachandran angles the NH and C R H bonds are approximately trans The physical origin of this Ψ angle AmIII 3 frequency dependence is that the hydrogen van der Waals radii in the C R H and NH bonds are in contact for positive Ψ angles Relative Impact of the Ψ and Φ Ramachandran Angles on the AmIII 3 Frequency. Although the projections of the NH and C R H bending motions on each other (and as a result the degree of coupling between them) depend on both the Ψ and Φ Ramachandran angles, an examination of a model of a peptide bond Asher et al. Mirkin and Krimm 73 theoretically examined the Ψ and Φ frequency dependence of the AmIII band of "alanine dipeptide" (NacetylLalanineNmethylamide). They concentrated on peptide bond 2, whose frequencies were close to those measured experimentally. Although Mirkin and Krimm claim in their conclusions, that AmIII frequency shows strong dependence on both Ψ and Φ Ramachandran angles, we note that the impact of changes in the Φ angle is relatively modest if we only include the allowed regions of the Ramachandran plot In the allowed regions of Ramachandran plot, Mirkin and Krimm 73 calculated a 2540 cm 1 AmIII frequency span over the allowed Ψ angles for fixed Φ angles In addition, the largest 16 cm 1 span in the AmIII frequency with Φ angle occurs in an almost forbidden region of the Ramachandran plot between the sheet and Rhelical regions (at Φ angles of 134°and 90°and Ψ angle of 60°, Figures 47 for details). Black line (s): Fit of calculated points using the eq 3 (see text for detail). Note: Grey regions show the forbidden and/or nearly forbidden Ψ Ramachandran angles based on recent Ramachandran plots. 1930 J. Phys. Chem. B, Vol. 110, No. 4, 2006 Mikhonin et al. 3 and 4). In contrast, in the Rhelical region of the Ramachandran plot the AmIII frequency of alanine dipeptide shows no more than 8 cm 1 Φ angular span, while in the strand region of the Ramachandran plot the AmIII frequency shows no more than 6 cm 1 Φ dependence Ianoul et al.'s 59 combined experimental and theoretical studies of AcXOCH 3 (X ) Val, Ile, Leu, Lys, Ala) revealed a 9 cm 1 AmIII 3 frequency shift upon an 18°increase of the Φ Ramachandran angle from 96 to 78°. In addition, Ianoul et al. also performed theoretical calculations for AlaAla at a fixed Rhelixlike Ψ angle of 21°and calculated only a 3 cm 1 AmIII 3 frequency upshift upon the 20°increase of Φ angle from 95°to 75°. Thus, Ianoul et al. never observed more than a 9 cm 1 shift of AmIII 3 frequency due to variation of the Φ Ramachandran angle. In addition, we recently 60 measured the UVRR AmIII 3 frequencies of two different secondary structure conformations in aqueous solutions with very similar Φ angles, but very different Ψ angles. Specifically, an equimolar mixture of PLL and PGA forms an antiparallel sheet 60 (Ψ ≈ 135°, Φ ≈ 139°), which shows an AmIII 3 frequency at 1227 cm 1 . In contrast individual PLL and PGA samples form extended 2.5 1 helices 60 (Ψ ≈ 170°, Φ ≈ 130°), which show AmIII 3 frequencies at ∼1271 cm 1 . To summarize, the total Φ angular span of the AmIII 3 frequencies appears experimentally 59 to be no more than 9 cm 1 and no more than 16 cm 1 in the allowed regions of the Ramachandran plot from theoretical calculations. Thus, we conclude that Ψ Ramachandran angular dependence of the AmIII 3 frequency dominates the Φ angular dependence in the allowed regions of Ramachandran plot. If we totally neglect the Φ angular dependence of AmIII 3 frequency, this could enable an error in the Ψdependent AmIII 3 frequency of no more than (8 cm 1 (since the total Φ angular span of AmIII 3 frequencies no higher than 16 cm 1 , Formation of PBwater and PBPB HBs upshift the AmIII 3 frequency, in part, due to the resulting increased C(O)dN double ν III3 (ψ,φ,HB PP ,HB PW ,T) = ν III3 (ψ,HB PP ,HB PW ,T) (2) ν III3 (ψ,HB PP ,HB PW ,T) = {ν 0 A sin(ψ R 0 )} + Δν III3 (HB PP ,HB PW ,T) (4) Peptide Secondary Structure Folding Reaction Coordinate J. Phys. Chem. B, Vol. 110, No. 4, 2006 1931 bond character. 75, The relationships given below by eqs 5 (for nonHB PB in a vacuum), 6AD (PB in aqueous solutions), and 7AC (PB in the absence of water) are shown in Correlation between AmIII 3 Frequency and Ψ Ramachandran Angle in the Absence of HB. We measured the UVR AmIII 3 frequencies for the AP Rhelix 42,89 (∼1263 cm 1 , 0°C), XAO PPII 42,43 (1247 cm 1 , 0°C), PLL and PGA 2.5 1 helix 60 (∼1271 cm 1 , 0°C), and PLLPGA mixture antiparallel sheet 60 (∼1227 cm 1 , 0°C) conformations of different polypeptides in aqueous solutions. Each of these conformations has known Ramachandran angles We can calculate the AmIII 3 frequencies that would result from the above peptide conformations in the fictitious case where the PB did not partake in any HB at all. This would be done by subtracting the HBinduced AmIII 3 frequency shifts By fitting the above four "nonHB" data points to eq 3, we obtain the following semiempirical relationship, which relates 1932 J. Phys. Chem. B, Vol. 110, No. 4, 2006 Mikhonin et al. the AmIII 3 frequency to the Ψ Ramachandran angle dependent coupling between NH and C R H bending motions The blue curve in Correlation of AmIII 3 Frequency and Ψ Ramachandran Angle for TwoEndOn PBPB HBs: Infinite rHelix, Interior Strands of Sheet in Water. Each PB in infinitely long Rhelices and in interior strands of multistranded sheets in aqueous solutions (Appendix, The green curve in The magenta curve in Peptide Secondary Structure Folding Reaction Coordinate J. Phys. Chem. B, Vol. 110, No. 4, 2006 1933 cm 1 HBinduced upshift as well as the temperaturedependent term to eq 5 and write The black curve in Correlation of AmIII 3 Frequency and Ψ Angle for a PB in Water If Its HB State Is Unknown. If the HB state of a PB in aqueous solution is unknown, we suggest the use of eq 6E, which is the "average" of eqs 6AD. This will minimize the error in determination of the Ψ Ramachandran angle and will allow the estimation of the Ψ angle with the error bounds discussed below. Correlation between AmIII 3 Frequency and Ψ Ramachandran Angle in Peptide Crystals. Figures 6 and 7 show that the crystal data appear to roughly follow the sinusoidal relationship between the AmIII 3 frequency and the Ψ Ramachandran angle (see red dashed curve in Anhydrous rHelical and Sheet Conformations. If we dehydrate a twoendon PBPB HB Rhelical conformation, we will see a 5 cm 1 AmIII 3 frequency downshift due to the loss of hydrogen bonding to the normally present sheath of water. The In the case of a PB where only the CdO group is involved in PBPB HB, we estimate that the AmIII 3 frequency is 12 cm 1 upshifted with respect to nonHB PB (Appendix, The In the case of PB, where only the NH group is PBPB HB, we estimate the AmIII 3 frequency to be 35 cm 1 upshifted with respect to nonHB PB (Appendix, The black curve in Thus, the families of eqs 6AD and 7AC predict the correlation between the AmIII 3 frequency and the Ψ angle for the common conformations of peptides and proteins. If the HB is known for a particular PB, the appropriate equation can be used to determine its Ψ angle from the observed AmIII 3 frequency. In the case where the HB state of a PB in aqueous solution is unknown, one can use eq 6E. These relationships will become less accurate if the PB has an unusual Φ angle or unusual HB pattern (see below). Prediction of UVRR AmIII 3 Frequencies of Other Secondary Structures. On the basis of the known Ψ Ramachandran angle and HB patterns, we can predict the AmIII 3 frequencies of other secondary structures such as the πhelix, 3 10 helix UVRR spectra of HEWL amyloid fibrils, 100 which are dominated by sheet conformations contain three spectroscopic features in the AmIII 3 region: ∼1210, ∼1230, and ∼1255 cm 1 . The dominating ∼1230 cm 1 feature certainly derives from antiparallel sheet, though a minor contribution of several turn conformations is also possible The error associated with neglecting the Φ angle also gives rise to the uncertainty in the Ψ angle determination. Ianoul et al. Additional bias can occur if we do not know the HB state of a PB in water. This could give rise to a bias of the AmIII 3 frequency of (6 cm 1 , which would lead to a Ψ angle bias of (6°in eq 6E. Thus, a typical UV Raman measurement of a typical sample would find a random error of e(8°in the Ψ angle, assuming a known HB state. However, extreme alterations in the unknown HB state of a PB in water could additionally bias the Ψ angle by (6°. Conclusions We used UV resonance Raman spectroscopy to investigate the dependence of the AmIII 3 frequency on the Ψ Ramachandran angle and on the nature of PB HBs. These results allow us to formulate relationships that allow us to estimate the Ψ Ramachandran angles from observed AmIII 3 frequencies for both aqueous solutions of peptides and proteins as well as for the anhydrous states of peptides and proteins. A typical Raman measurement of a typical sample would find a random error of e(8°in the Ψ angle, assuming a known HB state. However, if the HB state of a PB in water is unknown, extreme alterations in such a state could additionally bias the Ψ angle by (6°. We are optimistic that these relationships will be very useful for protein conformational studies, especially in the field of protein folding. This is because any attempt to understand reaction mechanisms, such as protein folding, requires elucidation of the relevant reaction coordinate(s). The Ψ angle is precisely the reaction coordinate that determines secondary structure changes. As shown elsewhere, 60 the correlation we propose can be used to determine features of the energy landscape along this Ψ reaction coordinate.
1Repeated Games With Intervention: Theory and Applications in Communications
"... In communication systems where users share common resources, users ’ selfish behavior usually results in suboptimal resource utilization. There have been extensive works that model communication systems with selfish users as oneshot games and propose incentive schemes to achieve Pareto optimal acti ..."
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In communication systems where users share common resources, users ’ selfish behavior usually results in suboptimal resource utilization. There have been extensive works that model communication systems with selfish users as oneshot games and propose incentive schemes to achieve Pareto optimal action profiles as noncooperative equilibria. However, in many communication systems, due to strong negative externalities among users, the sets of feasible payoffs in oneshot games are nonconvex. Thus, it is possible to expand the set of feasible payoffs by having users choose convex combinations of different payoffs. In this paper, we propose a repeated game model generalized by intervention. First, we use repeated games to convexify the set of feasible payoffs in oneshot games. Second, we combine conventional repeated games with intervention, originally proposed for oneshot games, to achieve a larger set of equilibrium payoffs and loosen requirements for users ’ patience to achieve it. We study the problem of maximizing a welfare function defined on users ’ equilibrium payoffs, subject to minimum payoff guarantees. Given the optimal equilibrium payoff, we derive the minimum intervention capability required and design corresponding equilibrium strategies. The proposed generalized repeated game model applies to various communication systems, such as power control and flow control.
Copyright and use of this thesis
, 2014
"... This thesis must be used in accordance with the provisions of the Copyright Act 1968. Reproduction of material protected by copyright may be an infringement of copyright and copyright owners may be entitled to take legal action against persons who infringe their copyright. Section 51 (2) of the Copy ..."
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This thesis must be used in accordance with the provisions of the Copyright Act 1968. Reproduction of material protected by copyright may be an infringement of copyright and copyright owners may be entitled to take legal action against persons who infringe their copyright. Section 51 (2) of the Copyright Act permits an authorized officer of a university library or archives to provide a copy (by communication or otherwise) of an unpublished thesis kept in the library or archives, to a person who satisfies the authorized officer that he or she requires the reproduction for the purposes of research or study.
Oscillation Criteria For Second Order Delay Differential Equations With Mixed Nonlinearities
, 2011
"... In this paper we establish oscillation criteria for second order delay differential equations with mixed nonlinearlities: The results obtained here generalize some of the existing results. ..."
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In this paper we establish oscillation criteria for second order delay differential equations with mixed nonlinearlities: The results obtained here generalize some of the existing results.