Detecting β-lactamase-mediated carbapenem resistance among Klebsiella pneumoniae isolates and other Enterobacteriaceae is an emerging problem. In this study, 15 bla KPC -positive Klebsiella pneumoniae that showed discrepant results for imipenem and meropenem from 4 New York City hospitals were characterized by isoelectric focusing; broth microdilution (BMD); disk diffusion (DD); and MicroScan, Phoenix, Sensititre, VITEK, and VITEK 2 automated systems. All 15 isolates were either intermediate or resistant to imipenem and meropenem by BMD; 1 was susceptible to imipenem by DD. MicroScan and Phoenix reported 1 (6.7%) and 2 (13.3%) isolates, respectively, as imipenem susceptible. VITEK and VITEK 2 reported 10 (67%) and 5 (33%) isolates, respectively, as imipenem susceptible. By Sensititre, 13 (87%) isolates were susceptible to imipenem, and 12 (80%) were susceptible to meropenem. The VITEK 2 Advanced Expert System changed 2 imipenem MIC results from >16 µg/mL to <2 µg/mL but kept the interpretation as resistant. The recognition of carbapenem-resistant K. pneumoniae continues to challenge automated susceptibility systems.

In order to analyze data on joint charged-particle/photon distributions from an experimental search (T-864, MiniMax) for disoriented chiral condensate (DCC) at the Fermilab Tevatron collider, we have identified robust observables, ratios of normalized bivariate factorial moments, with many desirable properties. These include insensitivity to many efficiency corrections and the details of the modeling of the primary pion production, and sensitivity to the production of DCC, as opposed to the generic, binomial-distribution partition of pions into charged and neutral species. The relevant formalism is developed and tested in Monte-Carlo simulations of the MiniMax experimental conditions.

We present results from MiniMax (Fermilab T-864), a small test/experiment at the Tevatron designed to search for the production of disoriented chiral condensate (DCC) in p −p collisions at √ s = 1.8 TeV in the forward direction, ∼ 3.4 < η <∼ 4.2. Data, consisting of 1.3 × 10 6 events, are analyzed using the robust observables developed in an earlier paper. The results are consistent with generic, binomial-distribution partition of pions into charged and neutral species. Limits on DCC production in various models are presented. I. INTRODUCTIONThe purpose of the MiniMax test/experiment (T-864) at the Fermilab Tevatron as set out in its proposal was to: (1) demonstrate the feasibility of operating spectrometers in the hostile environment of the far-forward, small angle region in high-energy hadron colliders; (2) search for the presence of disoriented chiral condensate (DCC) and possibly related exotic phenomena such as Centauro events; and (3) contribute data on inclusive spectra and multiplicity distributions in an unexplored region of phase space [1,2]. The experiment was proposed in April 1993, commissioned by January 1994, and upgraded in several stages during the next two years. The data reported here were acquired in January 1996.The principal purpose of this paper is to report the results of our DCC search. A signal for the formation and decay of disoriented chiral condensates [3,4] in hadronic and heavy-ion collisions is an anomalous joint multiplicity distribution of neutral and charged secondary pions, reflected in the probability density * Now where f is the fraction of the total number of pions which are neutral. (There are a variety of proposed mechanisms other than DCC which might also lead to this distribution [5]. We will not hereafter explicitly make this distinction.) Note that the distribution Eq. (1) differs markedly from the "generic", binomial partition of pions into charged and neutral species expected from ordinary production mechanisms. Neutral pions were not reconstructed in this experiment. Instead, we studied the joint multiplicity distribution of charged particles and gamma rays. In a recent publication [6], we showed that robust observables can be constructed from such data which still contain much of the information in Eq. (1) regarding the presence (or absence) of DCC. It is this method which we apply to the MiniMax data.The basic detector requirements of a DCC search, then, are to be able to count, event by event, the number of charged particles and photons in a given acceptance. The detailed design of the MiniMax detector was determined by a variety of considerations. The far-forward direction of production angles less than ∼ 50 mrad was chosen because cosmic ray data provide hints of novel phenomena in this region of phase space, and because it is largely unexplored at hadron colliders. In this region it is necessary to determine carefully the production angles of charged particles and the conversion products of photons. We therefore designed a forward spectrometer with a large nu...

A new proton injection kicker system is required for the Tevatron in the Run II era. The new system was designed to supply 1.25 kG-m into a magnetic aperture of 48 mm vertical x 71 mm horizontal x 5 m long with a 396 ns bunch spacing. The system is configured to be upgraded to a bunch spacing of 132 ns with additional pulsed power supplies. The design of the magnet incorporated some novel features in order to meet these requirements. These include adjustable bus spacing to set the inductance, balanced positive and negative high voltage buses and an integrated capacitive pickup. This system has been installed in the Tevatron since July 2000.

The PIP2IT test accelerator is under construction at Fermilab. Its ion source and Low Energy Beam Transport (LEBT) in its initial (straight) configuration have been commissioned to full specification parameters. This paper introduces the LEBT design and summarizes the outcome of the commissioning activities.