Theoretical foundations of operational research

The conclusions of both Parts One and Two complement and reinforce each other. After outlining the ideals of OR, I set out in Part One to find and scrutinize the philosophical foundations upon which some leading operations researchers have claimed that these ideals could be implemented. In chapters 2, 3, and 4 I argue that adopting (respectively) the positivist, conventionalist and/or idealist philosophies as the theoretical foundations upon which to build an adequate theory of inquiry for the purposes of OR would force it to abandon its ideals. These philosophies are interpreted as attempts on the part of academic operational researchers to stave-off the open-ended ambiguity and anarchy of inquiry which an unqualified interpretation of OR's ideals could engender. These attempts to give substance to the ideals of OR all exert a strong bias against raising questions about the nature of the subject-matter with which OR deals, and it in largely on these grounds that they are rejected in chapter 5 because of the implications which this has for the ideals of OR. One conclusion of Part One is that OR needs protection from such philosophies, and that a realist-type alternative at least provides this. I conclude by raising the doubt whether philosophy can provide much more to OR. The other major conclusion is that OR needs to understand its subject-matter before it can reasonably hope to implement its ideals. Given the general bias which we find in Part One against seriously considering the subject-matter of OR, we enter Part Two with some trepidation. Notwithstanding the philosophical bias against it, it is clear that OR must have a conception of the nature of its subject-matter. However, OR's ideals can just as easily be lost by inadequate attention to this task. In Part Two the biases discovered in Part One come home to roost. The first attempt to provide the ideals of OR with a substance on the basis of which its ideals can be implemented in an objective fray turns out to be just that, i.e., metaphysical 'substance' in the guise of a theory of management. We see in chapter 6 that to the extent to which this theory moves beyond merely asserting that management would 'take care' of OR's need for an objective basis, it presupposes a social theory which would show how social systems by their nature (if properly constructed) embody this objectivity. This move is foreshadowed in chapter 3 where we see Kuhn (who is taken as an exemplar of conventionalist philosophy) finally resorting to this device to prop up his conventionalism, against the growing weight of subjectivity under which it threatened to sag into the jaws of positivism. The social theory on which such claims rest is given detailed consideration in. chapter 7. In chapter 7 I give serious consideration to the possibility that OR's social theory, if it has one at all, will be developed in reaction to what it sees as the "problem of order", because this problem can be seen as but another way of stating its ideals in a specifically social way. Stating OR ideals in this way orients them directly to at least one aspect of the question of the nature of OR's subject-matter. We see that by employing, Durkheim's account of and solution to the social problem of order as a basis for comparison with OR (first as a homomorphism. and later as an isomorphism) that we are able to gain quite a firm grip on OR's social theory (and, hence, its grasp of its subject-matter). We see that this theory, although providing a justification for OR's theory of management (especially in its modern form), it is itself inadequate. The basis of the inadequacy, most fundamentally, is that the theory in question presupposes the very thing, that should be in question, namely, the nature of the social collective. I conclude with a specific illustration of the impact of this theory on the ideal of OR by analysing the inadequate treatment of power and conflict which it allows

Renal outcome of type 2 diabetes in South Africa - a 12-year follow-up study

Aims. Previous studies of type 2 diabetes mellitus have indicated a benign renal outcome after long-term  follow-up. The aim of this study was to determine how often renal failure due to diabetic nephropathy was  a cause of death in patients with type 2 diabetes.Methods. Prospective observational study of 59 South African patients with type 2 diabetes over a 12-year period. During the study repeated clinical evaluations were accompanied by measurements of serum creatinine, serum cholesterol, random blood sugar, and urine protein/ creatinine ratios.Results. The mean duration of diabetes at the end of the study was 17.8 years. There was a wide variation in the time from clinical diagnosis of diabetes to macroprQteinuria (mean 9.7 years, SD 5.9, range 0- 21) and the rate of deterioration of renal function. This rate correlated with poor control of blood pressure, a glucose level of> 14 mmol/1, heavy proteinuria, a high retinopathy score, a body mass index of < 28 and the number of pack years of smoking. At the end of the study 47 patients (79.7%) had died. Of these deaths 17 (28.8%) were due to chronic renal failure.Conclusions. In contrast to other studies we have shown that in a developing country renal failure in  type 2 diabetic patients is a major cause of death. Determining the prognosis for an individual patient is difficult as there are wide ranges in the time of onset of proteinuria, the rise in serum creatinine and the time to ultimate progression to end-stage renal failure

Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV

A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 inverse femtobarns. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.Comment: Submitted to JHE

Measurement of the t t-bar production cross section in the dilepton channel in pp collisions at sqrt(s) = 7 TeV

The t t-bar production cross section (sigma[t t-bar]) is measured in proton-proton collisions at sqrt(s) = 7 TeV in data collected by the CMS experiment, corresponding to an integrated luminosity of 2.3 inverse femtobarns. The measurement is performed in events with two leptons (electrons or muons) in the final state, at least two jets identified as jets originating from b quarks, and the presence of an imbalance in transverse momentum. The measured value of sigma[t t-bar] for a top-quark mass of 172.5 GeV is 161.9 +/- 2.5 (stat.) +5.1/-5.0 (syst.) +/- 3.6(lumi.) pb, consistent with the prediction of the standard model.Comment: Replaced with published version. Included journal reference and DO

Combined search for the quarks of a sequential fourth generation

Results are presented from a search for a fourth generation of quarks produced singly or in pairs in a data set corresponding to an integrated luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in 2011. A novel strategy has been developed for a combined search for quarks of the up and down type in decay channels with at least one isolated muon or electron. Limits on the mass of the fourth-generation quarks and the relevant Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a simple extension of the standard model with a sequential fourth generation of fermions. The existence of mass-degenerate fourth-generation quarks with masses below 685 GeV is excluded at 95% confidence level for minimal off-diagonal mixing between the third- and the fourth-generation quarks. With a mass difference of 25 GeV between the quark masses, the obtained limit on the masses of the fourth-generation quarks shifts by about +/- 20 GeV. These results significantly reduce the allowed parameter space for a fourth generation of fermions.Comment: Replaced with published version. Added journal reference and DO

Search for anomalous t t-bar production in the highly-boosted all-hadronic final state

A search is presented for a massive particle, generically referred to as a Z', decaying into a t t-bar pair. The search focuses on Z' resonances that are sufficiently massive to produce highly Lorentz-boosted top quarks, which yield collimated decay products that are partially or fully merged into single jets. The analysis uses new methods to analyze jet substructure, providing suppression of the non-top multijet backgrounds. The analysis is based on a data sample of proton-proton collisions at a center-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 5 inverse femtobarns. Upper limits in the range of 1 pb are set on the product of the production cross section and branching fraction for a topcolor Z' modeled for several widths, as well as for a Randall--Sundrum Kaluza--Klein gluon. In addition, the results constrain any enhancement in t t-bar production beyond expectations of the standard model for t t-bar invariant masses larger than 1 TeV.Comment: Submitted to the Journal of High Energy Physics; this version includes a minor typo correction that will be submitted as an erratu

Search for New Physics with Jets and Missing Transverse Momentum in pp collisions at sqrt(s) = 7 TeV

A search for new physics is presented based on an event signature of at least three jets accompanied by large missing transverse momentum, using a data sample corresponding to an integrated luminosity of 36 inverse picobarns collected in proton--proton collisions at sqrt(s)=7 TeV with the CMS detector at the LHC. No excess of events is observed above the expected standard model backgrounds, which are all estimated from the data. Exclusion limits are presented for the constrained minimal supersymmetric extension of the standard model. Cross section limits are also presented using simplified models with new particles decaying to an undetected particle and one or two jets

Measurement of the Z/gamma* + b-jet cross section in pp collisions at 7 TeV

The production of b jets in association with a Z/gamma* boson is studied using proton-proton collisions delivered by the LHC at a centre-of-mass energy of 7 TeV and recorded by the CMS detector. The inclusive cross section for Z/gamma* + b-jet production is measured in a sample corresponding to an integrated luminosity of 2.2 inverse femtobarns. The Z/gamma* + b-jet cross section with Z/gamma* to ll (where ll = ee or mu mu) for events with the invariant mass 60 < M(ll) < 120 GeV, at least one b jet at the hadron level with pT > 25 GeV and abs(eta) < 2.1, and a separation between the leptons and the jets of Delta R > 0.5 is found to be 5.84 +/- 0.08 (stat.) +/- 0.72 (syst.) +(0.25)/-(0.55) (theory) pb. The kinematic properties of the events are also studied and found to be in agreement with the predictions made by the MadGraph event generator with the parton shower and the hadronisation performed by PYTHIA.Comment: Submitted to the Journal of High Energy Physic

Search for supersymmetry in events with b-quark jets and missing transverse energy in pp collisions at 7 TeV

Results are presented from a search for physics beyond the standard model based on events with large missing transverse energy, at least three jets, and at least one, two, or three b-quark jets. The study is performed using a sample of proton-proton collision data collected at sqrt(s) = 7 TeV with the CMS detector at the LHC in 2011. The integrated luminosity of the sample is 4.98 inverse femtobarns. The observed number of events is found to be consistent with the standard model expectation, which is evaluated using control samples in the data. The results are used to constrain cross sections for the production of supersymmetric particles decaying to b-quark-enriched final states in the context of simplified model spectra.Comment: Submitted to Physical Review