Proton-electron mass ratio from laser spectroscopy of HD+ at the part-per-trillion level.

Recent mass measurements of light atomic nuclei in Penning traps have indicated possible inconsistencies in closely related physical constants such as the proton-electron and deuteron-proton mass ratios. These quantities also influence the predicted vibrational spectrum of the deuterated molecular hydrogen ion (HD+) in its electronic ground state. We used Doppler-free two-photon laser spectroscopy to measure the frequency of the v = 0→9 overtone transition (v, vibrational quantum number) of this spectrum with an uncertainty of 2.9 parts per trillion. By leveraging high-precision ab initio calculations, we converted our measurement to tight constraints on the proton-electron and deuteron-proton mass ratios, consistent with the most recent Penning trap determinations of these quantities. This results in a precision of 21 parts per trillion for the value of the proton-electron mass ratio.

Fundamental Transitions and Ionization Energies of the Hydrogen Molecular Ions with Few ppt Uncertainty.

We calculate ionization energies and fundamental vibrational transitions for H_{2}^{+}, D_{2}^{+}, and HD^{+} molecular ions. The nonrelativistic quantum electrodynamics expansion for the energy in terms of the fine structure constant α is used. Previous calculations of orders mα^{6} and mα^{7} are improved by including second-order contributions due to the vibrational motion of nuclei. Furthermore, we evaluate the largest corrections at the order mα^{8}. That allows us to reduce the fractional uncertainty to the level of 7.6×10^{-12} for fundamental transitions and to 4.5×10^{-12} for the ionization energies.

Theoretical Hyperfine Structure of the Molecular Hydrogen Ion at the 1 ppm Level.

We revisit the mα^{6}(m/M) order corrections to the hyperfine splitting in the H_{2}^{+} ion and find a hitherto unrecognized second-order relativistic contribution associated with the vibrational motion of the nuclei. Inclusion of this correction term produces theoretical predictions which are in excellent agreement with experimental data [K. B. Jefferts, Phys. Rev. Lett. 23, 1476 (1969)], thereby concluding a nearly 50-year-long theoretical quest to explain the experimental results within their 1-ppm error. The agreement between the theory and experiment corroborates the proton structural properties as derived from the hyperfine structure of atomic hydrogen. Our work furthermore indicates that, for future improvements, a full three-body evaluation of the mα^{6}(m/M) correction term will be mandatory.

Probing QED and fundamental constants through laser spectroscopy of vibrational transitions in HD(.).

The simplest molecules in nature, molecular hydrogen ions in the form of H2(+) and HD(+), provide an important benchmark system for tests of quantum electrodynamics in complex forms of matter. Here, we report on such a test based on a frequency measurement of a vibrational overtone transition in HD(+) by laser spectroscopy. We find that the theoretical and experimental frequencies are equal to within 0.6(1.1) parts per billion, which represents the most stringent test of molecular theory so far. Our measurement not only confirms the validity of high-order quantum electrodynamics in molecules, but also enables the long predicted determination of the proton-to-electron mass ratio from a molecular system, as well as improved constraints on hypothetical fifth forces and compactified higher dimensions at the molecular scale. With the perspective of comparisons between theory and experiment at the 0.01 part-per-billion level, our work demonstrates the potential of molecular hydrogen ions as a probe of fundamental physical constants and laws.

Four wave mixing oscillation in a semiconductor microcavity: generation of two correlated polariton populations.

We demonstrate a novel kind of polariton four wave mixing oscillation. Two pump polaritons scatter towards final states that emit two beams of equal intensity, separated both spatially and in polarization with respect to the pumps. The measurement of the intensity fluctuations of the emitted light demonstrates that the final states are strongly correlated.

Interference of coherent polariton beams in microcavities: polarization-controlled optical gates.

We demonstrate, theoretically and experimentally, a polarization-controlled optical gate based on a degenerate polariton-polariton scattering process occurring in semiconductor microcavities. Because of the interference between coherent polaritons, this process is observed in the case of polaritons generated from two collinearly polarized coherent pump beams. On the contrary, if the beams are cross polarized, the scattering is suppressed.

Quantum degeneracy of microcavity polaritons.

We investigate experimentally one of the main features of a quantum fluid constituted by exciton polaritons in a semiconductor microcavity, that is, quantum degeneracy of a macroscopic fraction of the particles. We show that resonant pumping allows us to create a macroscopic population of polaritons in one quantum state. Furthermore, we demonstrate that parametric polariton scattering results in the transfer of a macroscopic population of polariton from one single quantum state into another one. Finally, we briefly outline a simple method which provides direct evidence of the first-order spatial coherence of the transferred population.

Parametric polariton amplification in semiconductor microcavities.

We present novel experimental results demonstrating the coherence properties of the nonlinear emission from semiconductor microcavities in the strong coupling regime, recently interpreted by parametric polariton four-wave mixing. We use a geometry corresponding to degenerate four-wave mixing. In addition to the predicted threshold dependence of the emission on the pump power and spectral blueshift, we observe a phase dependence of the amplification which is a signature of a coherent polariton wave mixing process.

Tracing nitrate transport and environmental impact from intensive swine farming using delta nitrogen-15.

Natural-abundance delta15N showed that nitrate generated from commercial land application of swine (Sus scrofa domesticus) waste within a North Carolina Coastal Plain catchment was being discharged to surface waters by ground water passing beneath the sprayfields and adjacent riparian buffers. This was significant because intensive swine farms in North Carolina are considered non-discharge operations, and riparian buffers with minimum widths of 7.6 m (25 ft) are the primary regulatory control on ground water export of nitrate from these operations. This study shows that such buffers are not always adequate to prevent discharge of concentrated nitrate in ground water from commercial swine farms in the Mid-Atlantic Coastal Plain, and that additional measures are required to ensure non-discharge conditions. The median delta15N-total N of liquids in site swine waste lagoons was +15.4 +/- 0.2% vs. atmospheric nitrogen. The median delta15N-NO3 values of shallow ground water beneath and adjacent to site sprayfields, a stream draining sprayfields, and waters up to 1.5 km downstream were + 15.3 +/- 0.2 to + 15.4 +/- 0.2%. Seasonal and spatial isotopic variations in lagoons and well waters were greatly homogenized during ground water transport and discharge to streams. Neither denitrification nor losses of ammonia during spraying significantly altered the bulk ground water delta15N signal being delivered to streams. The lagoons were sources of chloride and potassium enrichment, and shallow ground water showed strong correlation between nitrate N, potassium, and chloride. The 15N-enriched nitrate in ground water beneath swine waste sprayfields can thus be successfully traced during transport and discharge into nearby surface waters.

Magnetic resonance imaging evaluation of monostotic fibrous dysplasia of the tibia.

The authors present a case report documenting the evaluation of monostotic fibrous dysplasia by magnetic resonance imaging. This type of evaluation demonstrates specificity for this disease process when combined with other imaging studies, laboratory findings, and clinical presentation. This technique is extremely useful in the identification of a no-touch lesion, allowing avoidance of an unnecessary bone biopsy.

Quantitative study of electroporation-mediated molecular uptake and cell viability.

Electroporation's use for laboratory transfection and clinical chemotherapy is limited by an incomplete understanding of the effects of electroporation parameters on molecular uptake and cell viability. To address this need, uptake of calcein and viability of DU 145 prostate cancer cells were quantified using flow cytometry for more than 200 different combinations of experimental conditions. The experimental parameters included field strength (0.1-3.3 kV/cm), pulse length (0.05-20 ms), number of pulses (1-10), calcein concentration (10-100 microM), and cell concentration (0.6-23% by volume). These data indicate that neither electrical charge nor energy was a good predictor of electroporation's effects. Instead, both uptake and viability showed a complex dependence on field strength, pulse length, and number of pulses. The effect of cell concentration was explained quantitatively by electric field perturbations caused by neighboring cells. Uptake was shown to vary linearly with external calcein concentration. This large quantitative data set may be used to optimize electroporation protocols, test theoretical models, and guide mechanistic interpretations.

Magnetic resonance imaging evaluation of heel pain.

Magnetic resonance imaging is superior to radiographic and scintigraphic examination for pathologic evaluation of the musculoskeletal system. Magnetic resonance imaging demonstrates increased sensitivity and specificity compared with radiographic evaluation, and equal sensitivity and increased specificity compared with scintigraphic examination. Two case studies of magnetic resonance imaging evaluation of heel pain involving a calcaneal stress fracture and a capillary hemangioma are presented.

"The branches into which bacteriology is now ramifying" revisited.

The American Society for Microbiology was originally founded in 1899 as the Society of American Bacteriologists. The transition from "bacteriology" to "microbiology" and from an emphasis on the identity of the membership (bacteriologists) to an emphasis on the discipline (microbiology) was a contentious one that occurred in several steps. This article reviews the history and events that accompanied this development.

Assessing the accuracy of conflicting autobiographical memories.

We examined criteria that rememberers and neutral audiences use to validate conflicting memories. In Experiment 1, rememberers described an incident that they recalled differently from someone else from their own and the other person's perspective. Rememberers and audiences then evaluated the accuracy of statements in both accounts, explained their accuracy ratings, and appraised the qualities of the memories. In Experiment 2, dyads who possessed conflicting memories of a shared past episode evaluated each other's recollections. In both studies, rememberers rated their own recollections as more accurate than other people's and based their judgments primarily on the internal coherence of the memories. Rememberers used consensus more frequently and sensory detail less often to evaluate other people's memories than their own. Audiences (Experiment 1) reported examining the consistency between the accounts and their own experiences; they also used consensus and normative behavior to a greater extent than rememberers. In both studies, rememberers judged their own accounts to be more detailed and coherent. Their ratings of detail and coherence predicted their ratings of accuracy.

A patient classification system for ambulatory care.

Patient classification systems (PCSs) for ambulatory care are difficult to develop because there are so few similarities among groups of patients and/or diagnoses in relation to the required nursing activities. In addition, the nursing activities required for specific patients and/or diagnoses also are dissimilar in relation to nursing time required. Therefore, a PCS was developed to assess staffing needs. This outpatient classification system reflects actual nursing time spent with each patient.

The presence of prostate-specific antigen-related genes in primates and the expression of recombinant human prostate-specific antigen in a transfected murine cell line.

Human prostate-specific antigen (PSA) has been shown as an aid in the early detection of prostate cancer (W. J. Catalona et al., J. Am. Med. Assoc., 270: 948-954, 1993) and was approved in 1994 by the Food and Drug Administration for early detection of prostate cancer. Immunotherapies directed against PSA have been suggested in patients with metastatic prostate cancer. One of the essential questions is to define which nonhuman species express PSA for experimental studies. Using Southern blot analyses, genes related to human PSA have been detected in several nonhuman primate species, including chimpanzee, orangutan, gorilla, macaque, and rhesus monkey, but not in other mammalian species, including rabbit, cow, pig, dog, rat, or mouse. Immunohistochemical staining with anti-human PSA antisera detected strong staining in both human and monkey prostatic epithelial cells with no reactivity to rat prostate cells. Because the PSA gene is not present in the murine genome, a matched set of murine cell lines has been developed that may be useful to study the biochemical functions of PSA and as an experimental target for PSA-directed immunotherapy. To establish such cell lines, a C57BL/6 murine colon adenocarcinoma cell line, MC-38, was transfected with a retroviral vector containing cDNA encoding the human PSA gene. Genetic analysis of a PSA-secreting clone, PSA/MC-38, demonstrated that the PSA gene had been stably integrated into the MC-38 genome. The PSA/MC-38 cell line was found to secrete PSA into tissue culture medium, producing a protein of approximately M(r) 30,000. In vivo, PSA/MC-38 grew as a s.c. tumor in male and female mice. PSA/MC-38 tumors grew more rapidly in athymic mice than in syngeneic C57BL/6 mice, and in both mouse strains, the PSA/MC-38 tumors grew more slowly than control vector-transduced tumors. PSA was detected in the serum and tumors of PSA/MC-38 tumor-bearing mice. It is proposed that PSA/MC-38 cells may be used as a murine tumor model to test potential therapeutic vaccines and other experimental therapies directed against PSA.

Prospective evaluation of topical antibiotics for preventing infections in uncomplicated soft-tissue wounds repaired in the ED.

OBJECTIVE: To determine differences in infection rates among uncomplicated, repaired wounds managed with: topical bacitracin zinc (BAC); neomycin sulfate, bacitracin zinc, and polymyxin B sulfate combination (NEO); silver sulfadiazine (SIL); and petrolatum (PTR). METHODS: This was a prospective, randomized, double-blind, placebo-controlled study conducted at a military community hospital with an emergency medicine residency program. Patients were enrolled if they: presented to the ED within 12 hours of injury and did not have puncture wounds, allergies to the agents used, or a history of immunocompromise; were not receiving antibiotics, chemotherapy, or steroids at the time of presentation; had not taken antibiotics within the preceding seven days; did not have an underlying fracture; and were not pregnant as determined by history. Local anesthetics without epinephrine and high-pressure irrigation with normal saline were used for all patients. Wound scrubbing, débridement, and polyglactin subcutaneous (SQ) suture placement were carried out when necessary. Interrupted simple sutures using a monofilament, nonabsorbable material were used for skin closure. Numbered, randomized vials were given to all patients, with standardized instructions to inspect, clean, and redress their wounds three times a day. The wounds were evaluated for clinical infection at the time of follow-up. RESULTS: Among the groups, there was no difference in patient ages; gender; wound location, type, length, or depth; time elapsed from injury to ED treatment; number of wounds scrubbed or necessitating débridement; number of SQ and cutaneous sutures used; and rate of compliance with returning the used vial of dispensed topical agent. The wound infection rates for the treatment groups were: BAC, six of 109 (5.5%); NEO, five of 110 (4.5%); SIL, 12 of 99 (12.1%); and PTR, 19 of 108 (17.6%) (p = 0.0034). CONCLUSION: The use of topical antibiotics resulted in significantly lower infection rates than did the use of a petrolatum control. BAC and NEO had the lowest wound infection rates.

A comparison of prostate cancer patients in Japan and the USA.

Clinical characteristics of prostate cancer patients were analyzed to compare the rates of progression of prostate cancer between patients in Japan (Gunma Urological Oncology Study Group: GUOSG) and the USA (Roswell Park Cancer Institute: RPCI), between 1980 and 1989. The stage of disease was more advanced and the age was greater in GUOSG patients compared with RPCI patients. However, the prostate cancer death rate of stage D patients at RPCI was significantly higher than that of the GUOSG. Moreover, the survival rate of stage A patients in the GUOSG was better than that of RPCI patients. The possibility of biases which may affect both the clinical characteristics and survival rates in the 2 populations studied is discussed. To determine whether there is a real difference in the rate of prostate cancer growth between the 2 countries will require a prospective study, ideally conducted in large population groups.

Pediatric home care--designing unique care for kids.

There is a growing need for pediatric home care services but selecting a provider is difficult. Pediatric home care calls for special abilities and qualifications, for numerous reasons.