PT-symmetric quantum field theory in D dimensions

PT-symmetric quantum mechanics began with a study of the Hamiltonian $H=p^2+x^2(ix)^\varepsilon$. A surprising feature of this non-Hermitian Hamiltonian is that its eigenvalues are discrete, real, and positive when $\varepsilon\geq0$. This paper examines the corresponding quantum-field-theoretic Hamiltonian $H=\frac{1}{2}(\nabla\phi)^2+\frac{1}{2}\phi^2(i\phi)^\varepsilon$ in $D$-dimensional spacetime, where $\phi$ is a pseudoscalar field. It is shown how to calculate the Green's functions as series in powers of $\varepsilon$ directly from the Euclidean partition function. Exact finite expressions for the vacuum energy density, all of the connected $n$-point Green's functions, and the renormalized mass to order $\varepsilon$ are derived for $0\leq D<2$. For $D\geq2$ the one-point Green's function and the renormalized mass are divergent, but perturbative renormalization can be performed. The remarkable spectral properties of PT-symmetric quantum mechanics appear to persist in PT-symmetric quantum field theory.Comment: 8 page

Appropriateness of referrals for single-photon emission computed tomography myocardial perfusion imaging (SPECT-MPI) in a developing community: A comparison between 2005 and 2009 versions of ACCF/ASNC appropriateness criteria

Appropriateness of referrals for myocardial perfusion imaging (MPI) in developing countries has not been extensively studied. Our study was conducted to describe the ordering practices of physicians and appropriateness of MPI referrals in Iran. We prospectively applied 2005 and 2009 versions of the Appropriateness Use Criteria published by the American College of Cardiology Foundation (ACCF) and the American Society of Nuclear Cardiology (ASNC) to 291 consecutive patients (age 55.3 ± 10.3 years) who underwent SPECT-MPI. For this purpose, we convened a panel, consisting of two academic cardiologists, one academic clinician in internal medicine, and one academic clinician in nuclear medicine. The panelists were invited for a face-to-face meeting to judge appropriateness of SPECT-MPI and independently assign a specific indication (scenario), whenever possible, for each case in accordance with ACCF/ASNC appropriateness scenarios. Based on the 2005 ACCF/ASNC criteria, SPECT-MPI studies were judged appropriate for 211 (72.5%), uncertain for 36 (12.4%), inappropriate for 32 (11.0%), and unclassifiable for 12 (4.1%) referrals. The same figures based on the 2009 version were 219 (75.3%), 15 (5.2%), 49 (16.8%), and 8 (2.7%) patients, respectively. Overall agreement between the 2005 and 2009 versions was good (κ 0.63). Lack of chest pain and age below 60 years were significant indicators increasing the likelihood of inappropriate referrals by 2.9-3.4 fold. Absence of diabetes mellitus and hypertension, a normal lipid profile, lack of a past history of myocardial infarction or cardiovascular interventions (CABGs or PCI), as well as lack of application and exercise ECG stress test as the gate keeper (keeping abnormal ETT or inability of the patient to perform exercise as the appropriate indication for SPECT-MPI referral) were significant indicators, decreasing the odds of appropriate referrals. Generally a higher percentage of referrals with inappropriate indications had normal MPI. Our study provides an evidence for the fact that SPECT-MPI ordering practices in our developing community largely parallel the ACCF/ASNC recommendations. The implementation of appropriateness criteria is feasible in clinical settings and might provide an alternative to utilization management. © 2011 American Society of Nuclear Cardiology

The Mid-Term Changes of Pulmonary Function Tests After Phrenic Nerve Transfer

Background: In the restoration of elbow flexion, the phrenic nerve has proven to be a good donor, but considering the role of the phrenic nerve in respiratory function, we cannot disregard the potential dangers of this method. Objectives: In the current study, we reviewed the results of pulmonary function tests (PFT) in four patients who underwent phrenic nerve transfer. Patients and Methods: We reviewed the results of serial spirometry tests, which were performed before and after phrenic nerve transfer surgery. Results: All patients regained Biceps power to M3 strength or above. None of our patients experienced pulmonary problems or respiratory complaints, but a significant reduction of spirometric parameters occurred after surgery. Conclusions: This study highlights the close link between the role of the phrenic nerve and pulmonary function, such that the use of this nerve as a transfer donor leads to spirometric impairments

Comparing Blood Sugar Levels Measured by the Glucometer in Healthy and Crushed Fingers to Predict Gangrene in Tehran, Iran

Background: Crushed fingers are one of the most common reasons that patients visit the emergency centers for hand surgery, and based on the level of injury, it can cause many disabilities for patients. It is difficult to decide the treatment strategies (amputation, aggressive revascularization, immediate or delayed complex reconstruction and immediate conservative treatment) for crushed fingers. Objectives: The current study aimed to compare the blood sugar (BS) levels measured by the glucometer in healthy and crushed fingers to predict gangrene in patients referred to 15 Khordad Hospital in Tehran, Iran. Methods: This cohort study was conducted on 265 patients with crushed fingers referred to the emergency center of 15 Khordad hospital in Tehran, Iran, from March 2015 to March 2016. Blood glucose levels were measured by glucometer in the crushed fingers and in the finger of the opposite side at the same time and measurements were recorded. Data were analyzed using t-test and chi-square test with SPSS software version 22. Results: The results showed that 317 crushed fingers of 265 patients were ischemic based on the color, temperature, capillary refill time and pulse oximetry and accordingly the vascular reconstruction was not possible. Of 317 crushed fingers, 61 (19.24%) became gangrene (all with sugar levels lower than 37). The mean BS levels of the amputated and non-amputated fingers were 33.5 ± 1.52 and 111.04 ± 15.27 mg/dL, respectively. Therefore, there was a significant difference in the mean BS level between the patients with amputated and non-amputated fingers (P < 0.001). Conclusions: The lower levels of sugar in crushed fingers compared to healthy fingers can help to diagnose gangrene in crushed finger

Flowability assessment of weakly consolidated powders

The inability of cohesive powders to flow consistently and reliably is a major cause of process downtime and reduced efficiency across a wide range of powder processing industries. Most methods to assess powder flowability fail at low consolidation pressures (<1 kPa). In this paper, the ball indentation technique is used to assess the flow behaviour of two powders at low stresses by determining the bed hardness. In parallel, the powders are subjected to shear testing in a range of high stresses, with the derived unconfined yield strength used, along with the indentation hardness to define the constraint factor (C). By using the latter, which is considered independent of the preconsolidation stress applied, the unconfined yield strength of the powders at low stresses are inferred from the penetration hardness measurements

Salt enhanced solvent relaxation and particle surface area determination via rapid spin-lattice NMR

This paper demonstrates the influence of surface charge chemistry on the application of nuclear magnetic relaxation measurements (NMR relaxometry) for the in situ determination of particle surface area, in the presence of high electrolyte concentration. Specifically, dispersions of titania, calcite and silica with and without 1 M KCl were investigated. The addition of salt, showed no significant change to relaxation measurements for titanium dioxide; however, a significant rate enhancement was observed for both calcite and silica systems. These differences were attributed to counterion layers forming as a result of the particles surface charge, leading to an increase in the relaxation rate of bound surface layer water. Further, changes appeared to be more pronounced in the silica systems, due to their larger charge. No enhancement was observed for titania, which was assumed to be due to the particles being at their isoelectric point, with no resulting counterion layer formation. Solvent relaxation was further used to successfully determine the surface area of particles in a dispersion using a silica standard reference material, with results compared to Brunauer-Emmett-Teller (BET) and spherical equivalent estimations. Two different dispersions of titanium dioxide, of different crystal phases, were shown to have NMR surface area measurements in good agreement with BET. Thus showing the technique was able to measure changes in surface charge when surface chemistry remained relatively similar, due to the reference silica material also being an oxide. In contrast, the NMR technique appeared to overestimate the calcite surface areas in reference to BET, which was assumed to occur due to both better dispersion in the liquid state of nanocrystallites and potential ion enhancement from the solubility of the calcite. These results highlight the potential of this technique as a fast, non-destructive and non-invasive method for dispersion analysis, but also show the competition between surface area and surface chemistry interactions on measured relaxation rates