We investigate the statistical properties of eigenvalues of pseudo-Hermitian random matrices whose eigenvalues are real or complex conjugate. It is shown that when the spectrum splits into separated ...sets of real and complex conjugate eigenvalues, the real ones show characteristics of an intermediate incomplete spectrum, that is, of a so-called thinned ensemble. On the other hand, the complex ones show repulsion compatible with cubic-order repulsion of non-normal matrices for the real matrices, but higher order repulsion for the complex and quaternion matrices.
In this paper, we extend previous studies conducted by the authors in a family of pseudo-Hermitian Gaussian matrices. Namely, we further the studies of the two pseudo-Hermitian random matrix cases ...previously considered, the first of a matrix of order N with two interacting blocks of sizes M and N − M and the second of a chessboard-like structured matrix of order N whose subdiagonals alternate between Hermiticity and pseudo-Hermiticity. Following an average characteristic polynomial approach, we obtain sequences of polynomials whose roots describe the average value of the polynomials of the matrices of the family at hand, for each case considered. We also present numerical results regarding the statistical behavior of the average characteristic polynomial, and contrast that to the spectral behavior of sample matrices of this family.
Characterizing the variability of the extragalactic sources used for calibration in the Atacama Large Millimeter/submillimeter Array (ALMA) is key to assess the flux scale uncertainty of science ...observations. To this end, we model the variability of 39 quasars which have been used by ALMA as secondary flux calibrators using continuous time stochastic processes. This formalism is specially adapted to the multi-frequency, quasi-periodic sampling which characterizes the calibration monitoring of ALMA. We find that simple mixtures of Ornstein-Uhlenbeck processes can describe well the flux and spectral index variability of these sources for Bands 3 and 7 (91.5 and 103.5, and 343.5 GHz, respectively). The spectral shape of the calibrators are characterized by negative spectral indices, mostly between −0.35 and −0.80, and with additional concavity. The model provides forecasts, interpolations, and uncertainty estimations for the observed fluxes that depend on the intrinsic variability of the source. These can be of practical use for the ALMA data calibrator survey and data quality assurance.
For a one dimensional system tight binding models are described by sparse tridiagonal matrices which describe interactions between nearest neighbors. In this report, we construct open and closed ...random tight-binding models based in the tridiagonal matrices of the so-called,β-ensembles of random matrix theory.
Background We analyzed association between viewing two-dimensional computed tomography (2D CT) images in addition to radiographs with radial head treatment recommendations after accounting for ...patient and surgeon factors in a survey-based experiment. Methods One hundred and fifty-four surgeons reviewed 15 patient scenarios with terrible triad fracture dislocations of the elbow. Surgeons were randomized to view either radiographs only or radiographs and 2D CT images. The scenarios randomized patient age, hand dominance, and occupation. For each scenario, surgeons were asked if they would recommend fixation or arthroplasty of the radial head. Multi-level logistic regression analysis identified variables associated with radial head treatment recommendations. Results Reviewing 2D CT images in addition to radiographs had no statistical association with treatment recommendations. A higher likelihood of recommending prosthetic arthroplasty was associated with older patient age, patient occupation not requiring manual labor, surgeon practice location in the United States, practicing for five years or less, and the subspecialties “trauma” and “shoulder and elbow.” Conclusions The results of this study suggest that in terrible triad injuries, the imaging appearance of radial head fractures has no measurable influence on treatment recommendations. Personal surgeon factors and patient demographic characteristics may have a larger role in surgical decision making. Level of evidence Level III, therapeutic case-control study.
It is shown that the ensemble of pseudo-Hermitian Gaussian matrices recently introduced gives rise in a certain limit to an ensemble of anti-Hermitian matrices whose eigenvalues have properties ...directly related to those of the chiral ensemble of random matrices.
It is shown how pseudo-Hermiticity, a necessary condition satisfied by operators of PT symmetric systems can be introduced in the three Gaussian classes of random matrix theory. The model describes ...transitions from real eigenvalues to a situation in which, apart from a residual number, the eigenvalues are complex conjugate.
Purpose
The introduction of transanal endoscopic or minimally invasive surgery has allowed organ preservation for rectal tumors with good oncological results. Data on functional and quality-of-life ...(QoL) outcomes are scarce and controversial. This systematic review sought to synthesize fecal continence, QoL, and manometric outcomes after transanal endoscopic microsurgery (TEM) or transanal minimally invasive surgery (TAMIS).
Methods
A systematic review of the literature including Medline, Embase, and the Cochrane Library databases was conducted searching for articles reporting on functional outcomes after TEM or TAMIS between January 1995 and June 2018. The evaluated outcome parameters were pre- and postoperative fecal continence (primary endpoint), QoL, and manometric results. Data were extracted using the same scales and measurement units as from the original study.
Results
A total of 29 studies comprising 1297 patients were included. Fecal continence outcomes were evaluated in 23 (79%) studies with a wide variety of assessment tools and divergent results. Ten studies (34%) analyzed QoL changes, and manometric variables were assessed in 15 studies (51%). Most studies reported some deterioration in manometric scores without major QoL impairment. Due to the heterogeneity of the data, it was not possible to perform any pooled analysis or meta-analysis.
Conclusions
These techniques do not seem to affect continence by themselves except in minor cases. The possibility of worsened function after TEM and TAMIS should not be underestimated. There is a need to homogenize or standardize functional and manometric outcomes assessment after TEM or TAMIS.
Background and hypothesis Deltoid disruption has traditionally been an absolute contraindication to performing a reverse total shoulder arthroplasty (RTSA), and options available to patients have ...been limited. We present a series of patients with deltoid tears that underwent concomitant RTSA with deltoid reconstruction. We hypothesize that this combined procedure provides an acceptable, functional alternative for this complex patient population. Materials and methods We retrospectively identified all patients who were treated by a single surgeon with a concomitant RTSA and deltoid reconstruction from 2004 to 2012 with minimum 24-month follow-up. Six shoulders in 5 patients met these criteria. The mean age was 69 years (range, 61-79 years), and the mean follow-up period was 76.8 months (range, 24-133 months). We compared preoperative and postoperative range of motion and Penn Shoulder Scores, including subscores, using paired t tests. Results Mean forward elevation and external rotation increased from 48° and 12°, respectively, to 120° and 22°, respectively. Penn scores increased from 45.2 to 77.8 postoperatively ( P = .03). The Penn satisfaction subscore, in particular, improved from 1.1 (of 10) to 9.0 ( P = .005). There was a low rate of recurrent deltoid failure (1 of 6 shoulders), and there were no infections or revisions. Discussion Deltoid reconstruction at the same time as RTSA is a viable treatment option as a salvage procedure for patients with deltoid deficiency who otherwise need RTSA for treatment of massive rotator cuff deficiency. In this small series, simultaneous RTSA and deltoid reconstruction resulted in a functional shoulder with a high level of satisfaction and good motion. Level of evidence Level IV; Case Series; Treatment Study
The purpose of this study was to compare the rates of wound complications and heterotopic ossification (HO) between patients who underwent acute total elbow arthroplasty (TEA) and those who underwent ...delayed TEA performed for the treatment of distal humerus fractures. Our hypothesis was that delayed surgery will have fewer wound complications but a higher rate of HO.
We retrospectively reviewed 104 patients who had undergone TEA performed at 1 of 3 institutions following a distal humerus fracture. The acute cohort, comprising 69 patients, underwent TEA within 2 weeks; the delayed cohort, comprising 35 patients, received treatment between 2 weeks and 6 months. The rates of wound complications, HO, clinically relevant HO (requiring excision or resulting in loss of functional range of motion), and reoperation were recorded. These patients were followed up for an average of 52 (interquartile range, 18.5–117) weeks.
Wound complications occurred in 10 patients (14.5%) in the early group and 7 (20.0%) in the delayed group. The overall rate of HO was 56.7% (59 patients). The rate of clinically relevant HO was 26.0% (27 patients), which was similar between the groups. Reoperation occurred in 20 patients (19.2%), which was similar between the groups. In the early group, 3 reoperations were performed for wound complications and 4 for HO. No patients required reoperation for these indications in the delayed group. The mean flexion-extension and supination-pronation arcs were 20°–130° and 80°–80°, respectively, which were similar between the groups. Rheumatoid arthritis and younger age were associated with increased odds of wound complications and reoperation.
The rates of reoperation, wound complications, and HO were overall higher than those previously reported; however, the study was underpowered to determine a difference between early and delayed treatment.
Therapeutic IV.
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