Unexpected positive culture (UPC) in adults revision spine surgery: a systematic review and meta-analysis of incidence, risk factors, and management.

BACKGROUND: Without clear signs of infection, spinal implant failure is attributed to mechanical overloads and aseptic loosening. However, how low-grade infections contribute to seemingly aseptic implant failure is unclear. PURPOSE: The systematic review examined unexpected positive cultures (UPCs) in revision spine surgery regarding prevalence, isolated pathogens, risk factors, and strategies to reduce infection among asymptomatic patients undergoing revision spine surgery. METHODS: We followed the PRISMA guidelines and searched four main databases (PubMed, EMBASE, SCOPUS, Web of Science) comprehensively until January 2023 for articles reporting UPC after presumed aseptic adult revision spine surgery. The UPC rates were pooled, and risk factors were compared with the culture-negative control group and represented as odds ratio (OR) or mean difference (MD). RESULTS: Fifteen studies of 1057 individuals were included in two groups: culture-positive or UPCs (n = 317) and culture-negative or control (n = 740). The overall UPC prevalence was 33.2% (317/1057, range: 0 to 53%, 95% CI = 30.2%-36.4%), and Cutibacterium acnes (43.0%, 95% CI = 37.4%-48.8%), Coagulase-negative Staphylococci (CoNS), (39.5%, 95% CI = 33.2%-46.2%), and Staphylococcus species in general (49.5%, 95%CI = 43.7%-55.4%) were reported the most common isolated microbes. 16.1% of the UPCs were polymicrobial. Risk factors associated with UPC rates were female sex (OR = 2.62, 95%CI = 1.76-3.90, P < 0.001), screw loosening (OR = 4.43, 95%CI = 1.31-15.02, P = 0.02), number of operated levels (MD = 0.77, 95%CI = 0.33-1.22, P = 0.0007), and shorter time since index surgery (MD = - 8.57 months, 95%CI = - 14.76, -2.39, P = 0.02). CONCLUSIONS: One-third of patients undergoing spine revision surgery revealed UPC in this study. Each UPC pathogen interpretation and antibiotic use decision should be interpreted case by case. LEVEL OF EVIDENCE: IV.

Inverse design of omnidirectional coherent absorbers for optical power beaming applications.

An efficient photovoltaic power converter is a critical element in laser power beaming systems for maximizing the end-to-end power transfer efficiency while minimizing beam reflections from the receiver for safety considerations. We designed a multilayer absorber that can efficiently trap monochromatic light from broad incident angles. The proposed design is built on the concept of a one-way coherent absorber with inverse-designed aperiodic multilayer front- and back-reflectors that enable maximal optical absorption in a thin-film photovoltaic material for broad angles. We argue that the broad bandwidth is achieved through an optimization search process that automatically engineers the modal content of the cavity to create multiple overlapping resonant modes at the desired angle or frequency range. A realistic design is provided based on GaAs thin films with inverse-designed multilayer binary AlAs/AlGaAs mirrors. The proposed device can pave the way for efficient optical power beaming systems.

Lung Injuries Associated with Scapular Fractures in Adult Traumatic Patients.

Background: Scapular fractures are among the orthopedic injuries, which are associated with other injuries, such as lung injuries. This study aimed to evaluate the prevalence of lung injuries associated with scapular fractures in traumatic patients referred to a main trauma center in the south of Iran. Methods: The present retrospective cross-sectional study was conducted from April 2016 to June 2019 on adult traumatic patients, who were referred to one of the main trauma centers in the south of Iran, and their data were recorded in the hospital information system. The patients with chest computed tomography, and those whose scapula fractures were reported and confirmed by a radiologist were included in this study. All patients' data were extracted from their medical files and then analyzed. Results: A total of 100 patients were enrolled, and the majority (78%) of the cases were male. The mean±SD age of the patients was 40.71±14.071 years, and 55% of the cases had lung injuries (P=0.158). Furthermore, most of the causes of scapular fracture were due to car-motorcycle accidents (30%) and car overturning (27%). Lung contusion (31%) and hemothorax (30%) were the most types of lung injuries. The mean±SD duration of hospitalization was estimated at 4.94±7.90 days. The mean age (OR=-0.207, P=0.039) and intensive care unit admission rate (OR=0.267, P=0.007) were statistically different in patients with and without lung injuries. Conclusion: Although scapula fractures were not significantly associated with lung injuries in this study, the occurrence of 55% of the lung injuries was clinically important, which should be considered by emergency physicians.

Prognostic Factors of Recurrence and Survival in Operated Patients with Colorectal Cancer.

BACKGROUND: The recurrence of colorectal cancers is considered to be one of the greatest post-surgical complications that is affected by various factors. This study was designed to investigate the prognostic factors that affect the recurrence and survival of patients with colon and rectal cancers. METHODS: A retrospective study was performed on 380 patients with colorectal cancers who underwent surgery were enrolled in the study (152 patients with colon cancer and 228 patients with rectal cancer). Preoperative serum albumin level, type of surgery, tumor size, differentiation grade, proximal, distal and radial, and marginal involvement, the total number of excised lymph nodes, the number of involved lymph nodes, and tumor stage were recorded. Also, the incidences of recurrence and metastasis were recorded during the study. RESULTS: 380 patients with a mean age of 57.11 years were enrolled in the study. 152 patients with an average age of 57.57 years were diagnosed as having colon cancer. Recurrence and metastasis occurred in two patients (1.3%) and five patients (3.3%), respectively. 18 patients (11.8%) died because of colon cancer. 228 patients with a mean age of 56.81 had rectal cancer. Recurrence was seen in 19 patients (8.3%) and metastasis in 33 patients (14.5%). 38 patients (16.7%) died because of rectal cancer. Tumor size and involved lymph nodes were independent prognostic factors for the recurrence and metastases of colon cancer. Only involved lymph nodes were associated with death due to colon cancer. Independent prognostic factors for rectal cancer metastasis include serum albumin level and age. The total number of excised lymph nodes was the only predictor of tumor recurrence and death in rectal cancer. The median survival times of colon and rectal cancers were 90 and 110 months, respectively. CONCLUSION: The size of the tumor and the number of involved lymph nodes were independent prognostic factors for recurrence and metastasis of colon cancer. Also, the number of involved lymph nodes was associated with colon cancer-related deaths. In the case of rectal cancer, serum albumin levels and age predicted metastases. Only the total number of excised lymph nodes had a reverse relationship with recurrence and rectal cancer-related death.

Salivary profile and dental status of patients with multiple sclerosis.

BACKGROUND: Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system. The MS patients may display biochemical changes in their cerebrospinal fluid, peripheral blood and saliva. Since the salivary profile plays a critical role in maintaining oral health and function, the analysis of saliva in the MS patients would be beneficial to prevent oral diseases, such as dental caries. OBJECTIVES: The aim of this study was to evaluate the dental status and salivary profile of the MS patients. MATERIAL AND METHODS: The study involved 25 MS patients and 25 healthy controls who were examined with regard to the calcium and phosphorus level, pH and flow rate of saliva as well as the decayed, missing and filled teeth (DMFT) index for permanent first molars. Student's t-test, the χ2 test and the Mann-Whitney test were utilized to compare the study groups. RESULTS: Significantly lower salivary flow rates were observed in the MS patients as compared to the controls. The salivary calcium and phosphorus levels were significantly higher in the case group during the first 6 years of the disease and 6-11 years after the onset of the disease, respectively, in comparison with the controls; however, there was no significant difference between the groups in terms of pH. The DMFT index for permanent first molars was higher in the MS patients than in the healthy controls, but not significantly. The number of carious and missing permanent first molars was significantly higher in the MS patients. CONCLUSIONS: Multiple sclerosis appears to significantly change the salivary profile and dental status of the patients.

Toggling between active and passive imaging with an omni-resonant micro-cavity.

While passive illumination schemes often utilize a broadband spectral acceptance, the performance of active illumination with a laser is improved by narrowband spectral filtering at the sensor. We present an experimental demonstration of an optical cavity structure that is capable of toggling between two performance limits: narrowband resonant and broadband omni-resonant transmission. To achieve omni-resonance without modifying the cavity, the incident optical field is pre-conditioned by associating each wavelength with a particular incidence angle that enables a broad continuous spectrum to resonate with the cavity. This strategy can help seamlessly combine passive and active illumination in the same system.

Statistical parity-time-symmetric lasing in an optical fibre network.

Parity-time (PT)-symmetry in optics is a condition whereby the real and imaginary parts of the refractive index across a photonic structure are deliberately balanced. This balance can lead to interesting optical phenomena, such as unidirectional invisibility, loss-induced lasing, single-mode lasing from multimode resonators, and non-reciprocal effects in conjunction with nonlinearities. Because PT-symmetry has been thought of as fragile, experimental realisations to date have been usually restricted to on-chip micro-devices. Here, we demonstrate that certain features of PT-symmetry are sufficiently robust to survive the statistical fluctuations associated with a macroscopic optical cavity. We examine the lasing dynamics in optical fibre-based coupled cavities more than a kilometre in length with balanced gain and loss. Although fluctuations can detune the cavity by more than the free spectral range, the behaviour of the lasing threshold and the laser power is that expected from a PT-stable system. Furthermore, we observe a statistical symmetry breaking upon varying the cavity loss.

Effect of class F fly ash on fine sand compaction through soil stabilization.

This paper presents the results of an experimental investigation carried out to evaluate the effect of fly ash (FA) on fine sand compaction and its suitability as a material for embankments. The literature review demonstrates the lack of research on stabilization of sandy material using FA. The study is concerned with the role of FA content in stabilized soil physical characteristics. The main aim of this paper is to determine the optimum quantity of FA content for stabilization of this type of soil. This is achieved through particle size distribution and compaction (standard proctor) tests. The sand was stabilized with three proportions of FA (5%, 10% and 15%) and constant cement content of 3% was used as an activator. For better comparison, the sand was also stabilized by 3% cement only so that the effect of FA could be observed more clearly. The results were in line with the literature for other types of soil, i.e. as the % of FA increases, reduction in maximum dry density and higher optimum moisture content were observed.

Basis-neutral Hilbert-space analyzers.

Interferometry is one of the central organizing principles of optics. Key to interferometry is the concept of optical delay, which facilitates spectral analysis in terms of time-harmonics. In contrast, when analyzing a beam in a Hilbert space spanned by spatial modes - a critical task for spatial-mode multiplexing and quantum communication - basis-specific principles are invoked that are altogether distinct from that of 'delay'. Here, we extend the traditional concept of temporal delay to the spatial domain, thereby enabling the analysis of a beam in an arbitrary spatial-mode basis - exemplified using Hermite-Gaussian and radial Laguerre-Gaussian modes. Such generalized delays correspond to optical implementations of fractional transforms; for example, the fractional Hankel transform is the generalized delay associated with the space of Laguerre-Gaussian modes, and an interferometer incorporating such a 'delay' obtains modal weights in the associated Hilbert space. By implementing an inherently stable, reconfigurable spatial-light-modulator-based polarization-interferometer, we have constructed a 'Hilbert-space analyzer' capable of projecting optical beams onto any modal basis.

GNSS space-time interference mitigation and attitude determination in the presence of interference signals.

The use of Space-Time Processing (STP) in Global Navigation Satellite System (GNSS) applications is gaining significant attention due to its effectiveness for both narrowband and wideband interference suppression. However, the resulting distortion and bias on the cross correlation functions due to space-time filtering is a major limitation of this technique. Employing the steering vector of the GNSS signals in the filter structure can significantly reduce the distortion on cross correlation functions and lead to more accurate pseudorange measurements. This paper proposes a two-stage interference mitigation approach in which the first stage estimates an interference-free subspace before the acquisition and tracking phases and projects all received signals into this subspace. The next stage estimates array attitude parameters based on detecting and employing GNSS signals that are less distorted due to the projection process. Attitude parameters enable the receiver to estimate the steering vector of each satellite signal and use it in the novel distortionless STP filter to significantly reduce distortion and maximize Signal-to-Noise Ratio (SNR). GPS signals were collected using a six-element antenna array under open sky conditions to first calibrate the antenna array. Simulated interfering signals were then added to the digitized samples in software to verify the applicability of the proposed receiver structure and assess its performance for several interference scenarios.

Evaluation of repair in duodenal perforation with human amniotic membrane: An animal model (dog).

BACKGROUND: There is a growing tendency toward application of human amniotic membrane (HAM) as a biologic substitute in various tissue injuries where a significant tissue loss is a matter of concern. In gastrointestinal injuries especially duodenal ones, some potential limitations in current surgical techniques contribute to not fully acceptable healing outcomes. Thus, this study was carried out to assess repair with HAM patch for duodenal defect in comparison with simple duodenoraphy in an animal model (dog). MATERIALS AND METHODS: A total of 15 male German shepherd dogs weighing 23-27 kg were randomly divided into two groups. Group A with 10 dogs, which were a candidate for duodenal repair by amniotic membrane patch and Group B consisted of 5 dogs perform simple duodenorraphy. A precise control was made to match all conditions except surgical technique. Macroscopic and microscopic features of the healed duodenal lumen in both groups were recorded. RESULTS: Gross evaluation revealed no difference in luminal diameter in both groups. Statistical analysis of duodenal diameter between both groups after operation also showed no significant difference (P v = 0.789). Histological assessment indicated less inflammation with better wound healing in Group A. CONCLUSION: It seems that repairing duodenal wall defect with HAM would result in better histological outcomes compared with what is seen in simple duodenoraphy in animal models. However, there is no significant difference regarding surgical findings.

Assessment of immunity against avian colibacillosis induced by an aroA mutant containing increased serum survival gene in broilers.

Colibacillosis is an important disease in the poultry industry which causes serious economic damages. As it is suggested that vaccination is one of the means to control colibacillosis, we tried to investigate the vaccine potential of a ∆aroA derivative of an O78:K80 avian pathogenic Escherichia coli containing increased serum survival gene. 490 chicks were selected as follows: For assessment of virulence of ∆aroA mutant, 30 chicks were divided into three groups and injected with 0.5ml of PBS or bacterial suspension containing either10(7) colony forming units (CFU) of mutant or parent strains via subcutaneous route. Macroscopic lesions and mortality rate were recorded in different groups during the week after challenge. For assessment of safety and immunogenicity of the ∆aroA mutant, three groups of 20 chicks were vaccinated by aerosol administration of 250 ml of suspension containing 10(8) CFU of mutant strain at days 1 and 14, while the two other groups received PBS or wild type strain. Macroscopic lesions and mortality rate were recorded in different groups until day 21. To determine whether the vaccination is protective against challenges or not, the chickens were vaccinated at days 1 and 14 and challenged intramuscularly with either a homologous or heterologous strains at day 21. Macroscopic lesions and mortality rate were recorded in different groups during the week after challenge. The results revealed that the ∆aroA mutant was slightly virulent, however it was safe and did not cause mortality, lesions or weight loss after vaccination. Antibody responses were similar in the control and mutant groups and vaccination did not induce a significant humoral immunity. The mutant could not protect chickens against both homologous and heterologous challenges. This could be due to several factors such as the high amount of maternal antibodies in the first two weeks of life, and the vaccination procedure.

Longitudinal Legendre polynomial expansion of electromagnetic fields for analysis of arbitrary-shaped gratings.

The Legendre polynomial expansion method (LPEM), which has been successfully applied to homogenous and longitudinally inhomogeneous gratings [J. Opt. Soc. Am. B24, 2676 (2007)], is now generalized for the efficient analysis of arbitrary-shaped surface relief gratings. The modulated region is cut into a few sufficiently thin arbitrary-shaped subgratings of equal spatial period, where electromagnetic field dependence is now smooth enough to be approximated by keeping fewer Legendre basis functions. The R-matrix propagation algorithm is then employed to match the Legendre polynomial expansions of the transverse electric and magnetic fields across the upper and lower interfaces of every slice. The proposed strategy then enhances the overall computational efficiency, reduces the required memory size, and permits the efficient study of arbitrary-shaped gratings. Here the rigorous approach is followed, and analytical formulas of the involved matrices are given.

Straight sinus stenosis as a proposed cause of perimesencephalic non-aneurysmal haemorrhage.

Perimesencephalic nonaneurysmal haemorrhage (PMNH), a term first coined in 1985, is a diagnosis of exclusion. It is considered a benign form of subarachnoid haemorrhage with a good prognosis and a low risk of rebleeding. Its precise aetiology has not yet been determined. Haemorrhage of venous origin has been proposed as a cause, and has been demonstrated to be associated with venous abnormalities of the basal vein of Rosenthal. We present a patient with PMNH in whom an 80% stenosis at the union of the vein of Galen with the straight sinus is demonstrated. We thus propose hypertensive venous rupture secondary to venous sinus stenosis as an alternative cause for PMNH.

The effect of the timing of antibiotics and surgical treatment on infection rates in open long-bone fractures: a 9-year prospective study from a district general hospital.

AIMS: To determine whether a delay of greater than 6h from injury to initial surgical debridement and the timing of antibiotic administration affect infection rates in open long-bone fractures. METHODS: We studied 248 consecutive open long-bone fractures in 237 patients over a 9-year period. The patients were followed until clinical or radiological union occurred or until a secondary procedure for non-union or infection was performed. RESULTS: Surgical debridement was performed within 6h of injury in 62% of cases and after 6h in 38% of cases. Infection rates were 7.8% and 9.6%, respectively, and the difference was not statistically significant (p=0.6438). The timing of antibiotic administration was not significantly related to the infection rate. CONCLUSION: Whilst open long-bone fractures should be treated expeditiously, we suggest that adherence to a 6h window has not been shown to affect infection rates nor has the timing of antibiotic administration during the acute phase.