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This was a retrospective cohort study.The present study is the first to investigate whether cervical paraspinal sarcopenia is associated with cervicothoracic sagittal alignment parameters after posterior cervical fusion (PCF).Few studies have investigated the association between sarcopenia and postoperative outcomes after cervical spine surgery.We retrospectively reviewed patients undergoing PCF from C2-T2 at a single institution between the years 2017-2020. Two independent reviewers utilized axial cuts of T2-weighted magnetic resonance imaging sequences to perform Goutallier classification of the bilateral semispinalis cervicis (SSC) muscles. Cervical sagittal alignment parameters were compared between subgroups based upon severity of SSC sarcopenia.We identified 61 patients for inclusion in this study, including 19 patients with mild SSC sarcopenia and 42 patients with moderate or severe SSC sarcopenia. The moderate-severe sarcopenia subgroup demonstrated a significantly larger change in C2-C7 sagittal vertical axis (+6.8 mm) from the 3-month to 1-year postoperative follow-up in comparison to the mild sarcopenia subgroup (-2.0 mm; P=0.02). The subgroup of patients with moderate-severe sarcopenia also demonstrated an increase in T1-T4 kyphosis (10.9-14.2, P=0.007), T1 slope (28.2-32.4, P=0.003), and C2 slope (24.1-27.3, P=0.05) from 3-month to 1-year postoperatively and a significant decrease in C1-occiput distance (6.3-4.1, P=0.002) during this same interval.In a uniform cohort of patients undergoing PCF from C2-T2, SSC sarcopenia was associated with worsening cervicothoracic alignment from 3-month to 1-year postoperatively.

BACKGROUND: Harrington instrumentation for adolescent idiopathic scoliosis (AIS) was revolutionary and allowed patients to mobilize faster as compared with patients treated with uninstrumented fusion. However, Harrington instrumentation provided correction of the deformity in 1 plane, resulting in limited sagittal plane control. Patients who received these 2 surgeries are aging, and to date, ultralong follow-up of these patients has not been reported. OBJECTIVE: The purpose of this study was to evaluate long-term patient-reported outcomes and radiographic parameters after Harrington nonsegmental distraction instrumentation vs uninstrumented fusion in the treatment of AIS. METHODS: Fourteen adult patients with AIS who were previously instrumented (n = 7) or uninstrumented (n = 7) were identified. Recent x-ray image measurements such as pelvic incidence (PI), sagittal vertical axis (SVA), pelvic tilt (PT), lumbar lordosis (LL), and pelvic incidence minus lumbar lordosis (PI-LL) were used to analyze deformities. Scoliosis Research Society-7 (SRS-7), Neck Disability Index (NDI), and Oswestry Disability Index (ODI) were used to evaluate patient-reported outcomes. Complications and rates of revision surgery were also evaluated. RESULTS: The mean age was 67.1 ± 5 years in the instrumented group and 64.1 ± 9 years in the uninstrumented group. There were no significant differences between instrumented and uninstrumented in SRS-7 (23.4 ± 2.9 vs 23.6 ± 2.6, P = 0.93), NDI (5.7 ± 4.5 vs 10.6 ± 4.5, P = 0.08), and ODI (9.7 ± 13.7 vs 9.4 ± 8.7, P = 0.99). Radiographic measurements of instrumented vs uninstrumented resulted in comparable PT (24.0 ± 7.9 vs 30.5 ± 4.7, P = 0.09), PI (61.3 ± 16.9 vs 67.2 ± 9.5, P = 0.47), LL (34.9 ± 14.4 vs 42.8 ± 11.0, P = 0.29), PI-LL (26.4 ± 25.1 vs 24.3 ± 10.4, P = 0.43), and SVA (38.1 ± 30.1 vs 52.3 ± 21.6, P = 0.37). There were 2 patients in the instrumented group who developed adjacent segment disease that required operative intervention compared with none in the uninstrumented group (P = 0.46). CONCLUSION: In long-term follow-up of instrumented and uninstrumented fusion, patients had similar patient-reported outcomes and radiographic parameters, although the instrumented cohort had higher rates of adjacent segment disease. LEVEL OF EVIDENCE: 4.

To our knowledge, metastasis to the site of congenital cervical fusion in Klippel-Feil syndrome (KFS) has not been described before and this report describes the management. The patient’s clinical presentation, imaging findings, and surgical treatment and outcomes are described. This is a case of a 47-year-old man with severe right C5 radicular symptoms with associated weakness as the first presentation of metastatic pancreatic cancer. The lesion involved the anterior and posterior elements of congenitally fused C4–C5 vertebrae with right foraminal involvement. The patient was managed with C2–T1 posterior spinal fusion and instrumentation with C4–C6 laminectomy and debulking of the lesion. The patient had resolution of his radicular symptoms. The cervical spine accounts for 8–15% of metastatic spine disease. KFS and congenital cervical fusion are uncommon. To our knowledge, this is the first description of a metastatic spine disease at a level of a congenital cervical fusion. The patient underwent successful surgical intervention consisting of posterior spinal fusion and laminectomy.

Study Design: Retrospective observational study. Objective: To establish occipital condyle dimensions (length, width, height), as well as the medialization angle necessary for safe occipital condyle screw placement in occipitocervical fixation. Methods: Between 1/2014-6/2014, patients who presented to a single level 1 academic trauma center emergency room and received computed tomography (CT) imaging of the cervical spine as part of routine clinical care were identified. After excluding patients with cervical fractures, neoplastic disease, or infection, 500 condyles representing 250 patients were analyzed. Condyle length, height, and width (all reported in millimeters [mm]) were evaluated on the sagittal, coronal, and axial series, respectively. Medialization angle (reported in degrees) was evaluated on the axial series of CT imaging. Measurements were compared by sex and age. Results: The average condyle length, width, and height were 18.6 millimeters (mm) (range, 14.5-23.0 mm), 10.5 mm (range, 7.4-13.8 mm), and 11.3 mm (7.1-15.3 mm), respectively. Additionally, the average occipital condyle medialization angle was 23° (range, 14-32°). Occipital condyles of men were significantly longer, wider, and taller (all comparisons, p < 0.05). The medialization angle was significantly steeper for women than men (p < 0.05). No measurement differences were appreciated by age. Conclusion: Our findings are similar to previous studies in the field; however, length appears slightly shorter. Further, measurement differences were appreciated by sex but not age. Thus, our measurement findings emphasize the importance of preoperative planning utilizing individual patient anatomy to ensure safe placement of occipital condyle screws for optimal outcomes.

This paper is dedicated to the study of an AOTF whose selectivity and side lobes are controlled thanks to acoustic square pulses with different and relatively low acoustic power. The behavior of the transmission function of a quasi-collinear acousto-optical tunable filter in T e O 2 is analyzed. The filter is used with acoustic pulses above 12 µs to manipulate the selectivity and with an electric power up to 600 mW to control the side lobes of the filtered spectrum. Using acoustic pulses requires working under a regime of a long optical pulse. The temporal response of the filter was considered to find the best parameters to perform the experiments. The selectivity was controlled from 1.3 nm to 2.5 nm with the use of acoustic pulses. The manipulation of the acoustic power applied to the filter improved the performance of the side lobe levels in regards to the main one from − 9 d B to − 12 d B .

Retrospective cohort study.The present study is the first to assess the impact of paraspinal sarcopenia on patient-reported outcome measures (PROMs) following posterior cervical decompression and fusion (PCDF).While the impact of sarcopenia on PROMs following lumbar spine surgery is well-established, the impact of sarcopenia on PROMs following PCDF has not been investigated.We performed a retrospective review of patients undergoing PCDF from C2 to T2 at a single institution between the years 2017 and 2020. Two independent reviewers who were blinded to the clinical outcome scores utilized axial cuts of T2-weighted magnetic resonance imaging sequences to assess fatty infiltration of the bilateral multifidus muscles at the C5-C6 level and classify patients according to the Fuchs Modification of the Goutalier grading system. PROMs were then compared between subgroups.We identified 99 patients for inclusion in this study, including 28 patients with mild sarcopenia, 45 patients with moderate sarcopenia, and 26 patients with severe sarcopenia. There was no difference in any preoperative PROM between the subgroups. Mean postoperative Neck Disability Index scores were lower in the mild and moderate sarcopenia subgroups (12.8 and 13.4, respectively) than in the severe sarcopenia subgroup (21.0, P0.001). A higher percentage of patients with severe multifidus sarcopenia reported postoperative worsening of their Neck Disability Index (10 patients, 38.5%; P =0.003), Visual Analog Scale Neck scores (7 patients, 26.9%; P =0.02), Patient-Reported Outcome Measurement Information System Physical Component Scores (10 patients, 38.5%; P =0.02), and Patient-Reported Outcome Measurement Information System Mental Component Scores (14 patients, 53.8%; P =0.02).Patients with more severe paraspinal sarcopenia demonstrate less improvement in neck disability and physical function postoperatively and are substantially more likely to report worsening PROMs postoperatively.3.

STUDY DESIGN Retrospective study. OBJECTIVE The objective of this study was to compared surgical site infection (SSI) rates between patients under lumbar discectomy with an operative microscope versus surgical loupes. SUMMARY OF BACKGROUND DATA Lumbar decompressions for herniated disks or lumbar stenosis are common spine procedures. Some studies have raised the concern that drape contamination of the operative microscope may be an additional risk for SSIs. We hypothesize that the use of the operative microscope for lumbar decompression procedures does not increase infection rates. METHODS A retrospective cohort analysis was performed on patients undergoing lumbar spinal decompressions via microscopic assistance (MA) or loupe assistance (LA) by 2 orthopedic spine surgeons at a tertiary academic medical center. Patients treated from November, 2012 to October, 2016 were enrolled. Variables including age, sex, race, body mass index, smoking status, length of surgery, intraoperative complications, estimated blood loss, and postoperative SSIs within 30 days were collected. RESULTS A total of 225 patients were included in the study. Sixty-three patients underwent LA lumbar decompression, and 162 underwent MA lumbar decompression. There were 72 female individuals/90 male individuals in the MA group and 31 female individuals/33 male individuals in the LA group. The MA was significantly older 45.2 versus 40.4 in LA, P-value of 0.02 and had a significantly higher body mass index (30.64 vs. 27.79, P

BACKGROUND CONTEXT As patients who underwent Harrington instrumentation for AIS approach older age, identifying the cervical spine deformity in the setting of preexisting Harrington instrumentation is important. There are few studies that have evaluated this topic. PURPOSE To evaluate cervical radiographic parameters and patient-reported outcomes in patients undergoing Harrington instrumentation for AIS. STUDY DESIGN/SETTING Observational. PATIENT SAMPLE Patients undergoing Harrington Instrumentation from 1962 to 1984. OUTCOME MEASURES Radiographic parameters, Neck Disability Index METHODS AIS patients undergoing Harrington instrumentation from 1962 to 1984 were identified. Inclusion criteria were completion of the patient-reported outcomes and recent cervical/scoliosis radiographs. Recent cervical and scoliosis radiographs were used to measure cervical deformity parameters (C2-C7 SVA, T1 slope, C2 SVA, C7 SCA). Neck Disability Index (NDI) was used to assess patient-reported outcomes. Using multivariate analysis, radiographic measurements and NDI scores were assessed. RESULTS A total of 32 patients met our inclusion criteria. The mean follow-up was 48 years (35-57). The mean age was 63.5± (51-82) years; 29 were females and 3 were males. The average age at which surgeries were performed was 15.4 (11-47) years with the average number of levels fused 9.7±1.7. Radiographic measurements resulted in C2-C7 SVA (mean, 24.7±11.1), T1 slope (mean, 26.1±10.7), C2 SVA (mean, 60.0±38.1) and C7 SVA (40.7±30.6). The mean NDI was 11.5 (0-48). Higher radiographic measurements of C2-C7 SVA (p=0.004) and C7 SVA (p=0.003) were strongly correlated with worse NDI scores, indicating decreased patient satisfaction with increased level of angulation. The T1 slope did not yield a statistically significant correlation (p=0.90). CONCLUSIONS Higher C2-C7 SVA and C7 SVA angles are correlated with worse patient reported outcomes in patients with minimum of 35 years follow-up after Harrington instrumentation for AIS. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Observational study.To evaluate the online ratings of spine surgeons and variables that may affect online ratings.Physician review Web sites (PRW) are rapidly growing for-profit businesses. Most orthopedic surgeons are rated on at least one PRW as are other surgical specialists. To date the online ratings of spine surgeons have not been evaluated.Cervical Spine Research Society surgeon ratings on five physician rating Web sites were performed in April 2016: "healthgrade.com," "vitals.com," "ratemd.com," "webmd.com," and "yelp.com." Numeric ratings from the PRWs were standardized on a scale of 0 to 100 with a higher score indicating positive ratings. Sex, practice sector (academic or private), specialty (orthopedics or neurosurgery), geographic location, and years of practice were also collected.A total of 209 spine surgeons were included in our study. Of the 209 spine surgeons, 208 (99.52%) were rated at least once in one of the five PRWs. Average number of ratings per surgeon was 2.96. Average rating was 80 (40-100). There were four female (1.92%) and 204 male surgeons (98.1%). There were 121 (58.2%) in academic practice and 87 (41.8%) in private practice. There were 175 (84.1%) orthopedic surgeons and 33 (15.9%) neurosurgeons. Most of the surgeons were Caucasian 163 (78.4%) and worked in the South and Northeast 135 (64.9%). Those in academic practice had significantly higher ratings (81.6 vs. 77.65; P = 0.026). Number of years in practice was significantly associated with ratings (P = 0.0003) with those in practice for 21 or more years having significantly lower ratings.In this first study evaluating the online ratings of spine surgeons, we found that 99.5% of spine surgeon had at least one rating on a PRW. The average score, 80, indicated mostly positive ratings. Being in practice for 20 years or less and being in academic practice significantly associated with higher ratings.4.

Objective Heterotopic ossification (HO) about the hip after total hip arthroplasty and internal fixation of the hip, pelvis, and acetabulum has been linked to surgical approach. However, no study has investigated surgical approach and HO in patients undergoing hemiarthroplasty. We therefore aimed to explore the influence of operative approach in patients undergoing hemiarthroplasty. Methods Through a retrospective case series at an Urban level I trauma center, we found 80 patients over the age of 60 undergoing hemiarthroplasty for femoral neck fractures from 2000 to 2009. Patient charts, operative notes, and radiographs were reviewed for demographics, operative approach (anterior: A, anterior-lateral: AL, posterior: P), and any development of HO. Fisher's exact test compared rates of HO among the three approaches. Student's t-tests compared Brooker Classification levels of HO among the approaches. Results 82 hemiarthroplasties (26 A, 32 AL, 24 P) were included for analysis. 22 patients (27%) had HO. There was no significant difference in the development of HO based upon surgical approach: A: 19% (n = 5); AL: 34% (n = 11); P: 25% (n = 6). There was a significant difference in the grade of HO based on Brooker Classification (BC) with the posterior approach resulting in significantly lower grade of HO: A (BC: 2.60); AL (BC: 2.64); P (BC: 1.50) (p = 0.012). Conclusions Our data is the first to evaluate surgical approach and HO in patients with hemiarthroplasty. Patients have a significant risk of developing higher grade HO based on surgical approach (A or AL). Orthopedists should be mindful of these risks when considering A or AL approaches.

We develop a new avenue to creating the optical spectrometer for the Guillermo Haro astrophysical observatory (Mexico), which combines specifically progressed prism spectrometer with modern acousto-optical approach in the frame of a joint instrument. This schematic arrangement includes two principal novelties. First, we exploit recently developed acousto-optical nonlinearity of the two-phonon light scattering in crystals with linear acoustic losses, which admits an additional physical degree of freedom. This effect allows us to use nonlinear acousto-optical effect for linear processing of optical signals in parallel regime within all the visible range. Similar effect is based on the possibility for tuning the frequency of elastic waves and admits the nonlinear apodization improving the dynamic range. Secondly, we are using the cross-disperser technique with acousto-optical processing for the first time to our knowledge. Additionally, the acousto-optical spectrometers can provide almost 100% efficiency in the acousto-optical interaction in the optimized regime. In the case of 4% Mg doped LiNbO 3 crystal the absorption edge can be shifted down to 370 nm for limited intensity of incoming light. The observation window of optical spectrometer in that observatory is ~ 9 cm, so that the theoretical estimations of maximal performances for a low-loss LiNbO3-crystal for this optical aperture at 405 nm give the spectral resolution 0.0523 A, resolving power 77,400, and number of spots 57,500. The illustrative proof-of-principle experiments with available for us 6-cm LiNbO 3 -crystal have been performed and demonstrated the spectral resolution 0.0782 A at 405 nm and resolving power 51,790.

This paper discuss on the dimensions that has been derived for the hearing-impaired mobile applications usability model. General usability model consist of general dimension for evaluating mobile application however requirements for the hearing-impaired are overlooked and often scanted. This led towards mobile application developed for the hearing-impaired are left unused. It is also apparent that these usability models do not consider accessibility dimensions according to the requirement of the special users. This complicates the work of usability practitioners as well as academician that practices research usability when application are developed for the specific user needs. To overcome this issue, dimension chosen for the hearing-impaired are ensured to be align with the real need of the hearing-impaired mobile application. Besides literature studies, requirements for the hearing-impaired mobile application have been identified through interview conducted with hearing-impaired mobile application users that were recorded as video outputs and analyzed using Nvivo. Finally total of 6 out of 15 dimensions gathered are chosen for the proposed model and presented.

An advanced conceptual design of a high-bit-rate triple product acousto-optical processor is presented that can be applied in a number of astrophysical problems. We briefly describe the Large Millimeter Telescope as one of the potential observational infrastructures where the acousto-optical spectrometer can be successfully used. A summary on the study of molecular gas in relatively old (age > 10 Myr) disks around main sequence stars is provided. We have identified this as one of the science cases in which the proposed processor can have a big impact. Then we put forward triple product acousto-optical processor is able to realize algorithm of the space-and-time integrating, which is desirable for a wideband spectrum analysis of radio-wave signals with an improved resolution providing the resolution power of about 105 - 106. It includes 1D-acousto-optic cells as the input devices for a 2D-optical data processing. The importance of this algorithm is based on exploiting the chirp Z-transform technique providing a 2D-Fourier transform of the input signals. The system produces the folded spectrum, accumulating advantages of both space and time integrating. Its frequency bandwidth is practically equal to the bandwidth of transducers inherent in acousto-optical cells. Then, similar processor is able to provide really high frequency resolution, which is practically equal to the reciprocal of the CCD-matrix photo-detector integration time. Here, the current state of developing the triple product acousto-optical processor in frames of the astrophysical instrumentation is shortly discussed.

Optical spectrometer of the Guillermo Haro astrophysical observatory (Mexico) realizes investigations in the visible and near-infrared range 350 - 800 nm and exploits mechanically removable traditional static diffraction gratings as dispersive elements. There is a set of the static gratings with slit-densities 150 - 600 lines/mm and optical apertures 9 cm × 9 cm that provide the first order spectral resolution from 0.8 to 3.2 A/pixel, respectively. However, the needed mechanical manipulations, namely, replacing the static diffraction gratings with various resolutions and following recalibration of spectrometer within studying even the same object are practically inconvenient and lead to wasting rather expensive observation time. We suggest exploiting an acousto-optical cell, i.e. the dynamic diffraction grating tunable electronically, as dispersive element in that spectrometer. Involving the acousto-optical technique, which can potentially provide electronic control over the spectral resolution and the range of observations, leads to eliminating the abovementioned demerits and improving the efficiency of analysis.

We develop an advanced approach to the optical spectrometer with acousto-optical dynamic grating for the Guillermo Haro astrophysical observatory (Mexico). The progress consists of two principle novelties. First is the use of the acousto-optical nonlinearity of two-phonon light scattering in crystals with linear acoustic losses. This advanced regime of light scattering exhibits a recently revealed additional degree of freedom, which allows tuning of the frequency of elastic waves and admits the nonlinear apodization improving the dynamic range. The second novelty is the combination of the cross-disperser with acousto-optical processing. A similar pioneering step provides an opportunity to operate over all the visible range in a parallel regime with maximal achievable resolution. The observation window of the optical spectrometer in that observatory is ∼9 cm, so that the theoretical estimations of maximal performances for a low-loss LiNbOsub3/subcrystal for this optical aperture at λ=405 nm give spectral resolution of 0.0523 Å, resolving power of 77,400, and 57,500 spots. The illustrative proof-of-principle experiments with a 6 cm LiNbOsub3/subcrystal have been performed.

In this work, the non-linear acousto-optical interaction is studied for the collinear and the non-collinear cases. First, a non-linear regime of the collinear acoustooptical interaction is considered with acoustic waves of finite amplitude considering the acoustic loses in a crystalline acousto-optical cell. The results of this analysis were confirmed first in a calcium molybdate (CaMoO4) acoustooptical cell. After this, the results were extrapolated to predict the performances of a lithium niobate (LiNbO3) acousto-optical cell oriented to the application in astrophysical spectroscopy near the ultraviolet range. This material, specifically, was in need of further analysis due to known phenomena within it that could affect the capabilities of such cell. Then, the non-collinear acousto-optical interaction is studied for the multiphonon light scattering in the Bragg regime. This regime allows only two possible cases of multiphonon light scattering, namely, the two- and three-phonon acoustooptical interaction. Together with this, a specific degree of freedom for this acousto-optical interaction is introduced to regulate the acoustic frequency necessary for the interaction to occur. The multiphonon light scattering was theoretically analyzed and experimented in two different crystals; calomel (Hg2Cl2) for the two-phonon interaction and tellurium dioxide (TeO2) for the three-phonon case. En este trabajo se estudia la interacción acusto-óptica no-lineal para los regímenes colineal y no-colineal. Primero, un régimen no-lineal de la interacción acustoóptica colineal está bajo consideración con ondas acústicas de amplitud finita tomando en cuenta las pérdidas acústicas en una celda acusto-óptica cristalina. Los resultados de este análisis fueron confirmados primero en una celda acustoóptica de molibdato de calcio (CaMoO4). Luego de esto, los resultados fueron extrapolados para predecir el desempeño de una celda acusto-óptica de niobato de litio (LiNbO3) encaminada a su aplicación en espectroscopía astrofísica cerca del rango ultravioleta. Este material en particular, necesitó de un análisis más profundo debido a fenómenos conocidos en él que podrían afectar las capacidades de una celda de este material. Después, la interacción acusto-óptica no colineal se estudió para el esparcimiento multifonón de luz en el régimen de Bragg. Este régimen sólo permite dos posibles casos, la interacción acusto-óptica de dos y de tres fonones. Junto con esto, un grado de libertad específico de esta interacción acusto-óptica se introdujo para regular la frecuencia acústica necesaria para que ocurra la interacción. El esparcimiento multifonón de luz se analizó teoréticamente en dos cristales diferentes; cloruro de mercurio (Hg2Cl2) para el caso de la interacción de dos fonones y dióxido de telurio (TeO2) para el caso de tres fonones.

We consider the collinear backward light scattering as one of potential physical mechanisms for creating an advanced collinear acousto-optical filter with significantly improved spectral resolution. Within co-directional crystalline collinear acousto-optical filters, the resolution is inversely proportional to the material’s birefringence, which is ~0.1 in the best case of LiNbO3-crystal. For the backward light scattering this parameter is replaced by the twice refractive index, so that the gain achieves > 45 times in LiNbO3-crystal. Thus, one can expect the resolution ~0.002 A instead of the value ~0.1 – 0.2 A recently obtained by us experimentally for co-directional geometry in that crystal. Moreover, the collinear backward light scattering can be implemented in an extended amount of available materials. However, the main limitation for applying the phenomenon is the acoustic attenuation in ultra-high frequency range peculiar to the materials for acousto-optical filters. Linear acoustic attenuation reduces the length of acousto-optical interaction and limits the spectral resolution. At an initial stage, our studies are concentrated on physical aspects of this phenomenon as well as on possibilities of its application to creating the acousto-optical filters of a high resolution. In particular, the frequency band-shapes of the scattered light intensity exhibit a tendency to specific acousto-optical nonlinearity, i.e. to more and more rectangular profile as the acoustic power density grows. Results of this analysis confirm the above-noted estimations for a triplet of trigonal acousto-optical crystals, having possibly lower acoustic attenuation.

We develop a multi-band spectrometer with a few spatially parallel optical arms for the combined processing of their data flow. Such multi-band capability has various applications in astrophysical scenarios at different scales: from objects in the distant universe to planetary atmospheres in the Solar system. Each optical arm exhibits original performances to provide parallel multi-band observations with different scales simultaneously. Similar possibility is based on designing each optical arm individually via exploiting different materials for acousto-optical cells operating within various regimes, frequency ranges and light wavelengths from independent light sources. Individual beam shapers provide both the needed incident light polarization and the required apodization to increase the dynamic range of a system. After parallel acousto-optical processing, data flows are united by the joint CCD matrix on the stage of the combined electronic data processing. At the moment, the prototype combines still three bands, i.e. includes three spatial optical arms. The first low-frequency arm operates at the central frequencies ~60-80 MHz with frequency bandwidth ~40 MHz. The second arm is oriented to middle-frequencies ~350-500 MHz with frequency bandwidth ~200-300 MHz. The third arm is intended for ultra-high-frequency radio-wave signals about 1.0-1.5 GHz with frequency bandwidth

Regime of effective non-collinear acousto-optical interaction with tangential phase matching had been identified and previously observed only in two limiting cases: in tellurium dioxide (TeO 2 ) at low acoustic frequencies (~60 MHz) and in rutile (TiO 2 ) at ultra-high frequencies (~5 GHz). Both these limits are motivated by optical properties of the chosen materials. Low frequencies in TeO 2 admit designing a wide-aperture acousto-optical cell, but limit the frequency bandwidth. While an acousto-optical cell made of TiO 2 has very small aperture and exhibits low spectral resolution due to the effect of linear acoustic attenuation. Instead of those limits, we propose an advanced regime of the anomalous acousto-optical interaction with tangential phase matching, which allows us varying the frequency range and optimizing all the performances (for instance, the spectral resolution) of a wide-aperture acousto-optical cell made of the chosen crystal, as the case requires. Recently, we had suggested and successfully tested experimentally the revealed additional degree of freedom, i.e. the action of the tilt angle within the refractive indices ellipsoids to manipulate by the performances of crystalline acousto-optical cells. Now, we consider an opportunity of refining this additional degree of freedom within those ellipsoids of crystalline acousto-optical cell through some declination of the acoustic beam. For our investigations, the lithium niobate (LiNbO 3 ) and rutile (TiO 2 ) crystals of about 5 cm length, operating with the slow-shear acoustic mode along the acoustic axes had been selected. The needed theoretical analysis, numerical estimations, and 3D-vector diagrams have been developed to reveal potential benefits of the proposed technique.

Nonoperative management of fractures in the setting of diffuse idiopathic skeletal hyperostosis (DISH) or ankylosing spondylitis is often unsuccessful. The subaxial spine is a common site of hyperextension fractures in the setting of DISH. Fractures of the upper cervical spine are uncommon in DISH. We report, to our knowledge, the first case describing successful nonoperative management of a type 2 odontoid fracture in a patient with DISH. We discuss the patient’s initial presentation, physical examination, imaging findings, and management. A 73-year-old male presented with neck pain to the emergency department after sustaining a ground-level fall. Computed tomography of the cervical spine demonstrated a minimally displaced type 2 odontoid fracture in the setting of extensive DISH. He was immobilized with a hard cervical collar as the definitive management of his fracture. The collar was discontinued after 3 months. At his 2-year follow-up, he had a stable fibrous nonunion at the fracture site with tolerable neck pain. Flexion–extension radiographs demonstrated a stable alignment, and nonoperative management was continued. In selected patients with odontoid fractures in the setting of DISH, there is a role for nonoperative management alongside close monitoring.

Performances of any system for data processing based on acousto-optical technique are mainly determined by parameters of the acousto-optical cell (AOC) exploited within the schematic arrangement. Here, basic properties of the AOC, involved into a novel processor for precise optical spectrum analysis dedicated to modern astrophysical applications, are considered. Because potential applications of this processor will be focused on investigations in extra-galactic astronomy as well as studies of extra-solar planets, an advanced regime of the non-collinear two-phonon light scattering has been elaborated for spectrum analysis with significantly improved spectral resolution. Under similar uprated requirements, the AOC, based on that specific regime in the calomel (Hg 2 Cl 2 ) crystal, had been chosen, and its parameters were analyzed theoretically and verified experimentally. Then, the adequate approach to estimating the frequency/spectral bandwidth and spectral resolution had been developed. The bandwidth was calculated and experimentally realized with the additionally involved tilt angle of light incidence, allowing variations for acoustic frequencies. The resolution was characterized taking into account its doubling peculiar to the nonlinear two-phonon mechanism of light scattering. Proof-of-principle experiments were performed with the calomel AOC of 52 mm optical aperture, providing ~94% efficiency in the transmitted light due to the slow-shear acoustic mode of finite amplitude (the acoustic power density ~150 mW/mm 2 ) with the velocity of 0.347×105 cm/s at the radio-wave acoustic frequency ~71 MHz. As a result, we have obtained the spectral resolution

Our work is devoted to the collinear acousto-optical filter governed by the acoustic waves of finite amplitude. It represents a novel bulk-optical component, namely, the dispersive element for optical spectroscopy. This filter is based on specifically doped lithium niobate single crystal that unexpectedly works in the near ultraviolet range as well as this material usually works in the visible range. We examine the phenomena affecting the filter transmission efficiency and its resolution, i.e. the light-induced absorption and photorefraction. A new nonlinear approach is used to characterize performances of this collinear LiNbO3 acousto-optical filter exploiting our revealed specific acousto-optical nonlinearity. We have carried out the experiments with the collinear filter based on the congruent LiNbO3 crystal of 6.3 cm length at λ = 405 and 440 nm to verify our analysis and estimations. We also explore an opportunity to trade an amount of the efficiency to improve the spectral resolution. The transmission efficiency steeply increases with increasing light wavelength and with decreasing length of the filter, nevertheless the efficiency still remains higher than 30% in the near ultraviolet, if the spectral resolution is limited by δλ = 0.28–0.29 A. Moreover, we demonstrate the possibility to reach a resolution as high as δλ = 0.12–0.15 A (R > 24600), preserving at the same time an efficiency higher than 10% over the spectral interval that we considered. It looks like our filter holds the best to our knowledge experimentally confirmed spectral resolution for any collinear acousto-optical spectrometers dedicated to space/airborne operations.

Foot pathologies are common in nearly 80% of all elderly patients, and studies have indicated inappropriate footwear as one of the major underlying cause. It has been postulated that ill-fitting shoe wear affects plantar pressure, thus exacerbating weak balance. Complications arising from foot pathologies, which include difficulty in maintaining balance, have increased the risk of falls that can result in fractures and other serious injuries. The link between footwear and the onset or progression of certain foot pathologies has emphasized the need to explore and promote preventative measures to combat the issue. Wider and higher toe boxed shoes, along with sneakers, are examples of footwear documented to evenly distribute plantar pressure, increase comfort, and facilitate appropriate balance and gait. Ultimately, the use of appropriate footwear can help to better stabilize the foot, thus reducing the risk of sustaining debilitating physical injuries known to drastically decrease the quality of life among the geriatric population.

We present an original approach to precise optical spectrum analysis based on combining the nonlinear acousto-optical processing with the cross-disperser technique. This novelty gives us a possibility to overlap all the visible range by the parallel analysis with a gained spectral resolution. For this goal, an advanced rutile-made acousto-optical cell has been designed and tested as dynamic acoustic grating at ultrahigh-frequency to provide the needed slit density to increase the resolving power and the nonlinear apodization to improve the profile of a resolvable spot. Theoretical estimations were developed for low-loss 6-cm rutile-crystal at λ=440 nm, and they show that one can expect the spectral resolution 0.0609 Å, resolving power 72,250, and the number of resolvable spots ∼39,200. The illustrative proof-of-principle experiments with that rutile-crystal-made acousto-optical cell have been carried out. Experimentally we have obtained the spectral resolution ∼0.0815 Å and resolving power ∼54,000.

This investigation represents a deep and advanced analysis of exploiting lithium niobate (LiNbO3) crystals for the collinear acousto-optical tunable filter (AOTF) in violet and near ultraviolet ranges. The selection of this material is motivated by its high birefringence, which is a key parameter for improving the resolution of AOTF. For this matter, we take into account all the important factors that can deteriorate the resolution in order to find extreme conditions for the best performances. In concrete, we analyze the well- known photorefraction effect accompanied by the light induced absorption in those ranges for the LiNbO3 crystals doped by selected materials. The best observed results have been obtained with magnesium (Mg) dopant in the congruent melt of LiNbO3, which also shifts the absorption edge far into the middle UV-range. This analysis had made it possible to formulate the physical criterion determining the enlarged practical limitations of the incident light power density. Together with previously studied non-uniformity and dispersion of the birefringence along the length of acousto-optical interaction in a crystal, we exploit the recently discovered and experimentally confirmed acousto-optical nonlinearity, which can improve the transmission function inherent in the collinear interaction via applying the acoustic waves of finite amplitude in the AOTF. As a result, the obtained spectral resolution is the best available for any collinear AOTF to our knowledge.

We investigate the components of dissipative multi-wave solitons in the form of three-wave weakly coupled states originating within the collinear acousto-optical interaction due to acoustic waves of finite amplitude. This investigation is carried out in a square-law nonlinear birefringent medium with linear optical losses, theoretically and experimentally. Theoretically, we study the three-wave collinear acousto-optical interaction using several acoustic pulse profiles, with the cases of infinite support (when the acoustic pulse envelope is gradually vanishing on the boundaries) and compact support (when acoustic pulse envelope is cut down on the boundaries), and consider the appropriate boundary conditions in a quasi-stationary regime with the phase mismatch. As a theoretical result, one has found that the system can be described; in particular, by the cnoidal Jacobi elliptic functions whose limiting cases lead to hyperbolic and trigonometric solutions. The experiments dedicated to examine these theoretical results have been done with a X-ray irradiated α-quartz crystalline cell enabling the collinear acousto-optical interaction. The cell used the pure longitudinal acoustic wave with the frequency mismatch along the 6 cm interaction length. Two types of acoustic pulses had been generated, namely, hyperbolic-secant pulse (infinite support) and a bounded rectangular pulse (compact support). During these experiments one had observed the optical components peculiar to the mismatched weakly coupled states. Rather well agreement between the theoretical model, simulated numerically, and the obtained data of measurements for the frequency detuning, acoustic power density, and efficiency of the coupled states localization have been achieved.

During subsequent development of the recently proposed multi-frequency parallel spectrometer for precise spectrum analysis of wideband radio-wave signals, we study potentials of new acousto-optical cells exploiting selected crystalline materials at the limits of their capabilities. Characterizing these wide-aperture cells is non-trivial due to new features inherent in the chosen regime of an advanced non-collinear one-phonon anomalous light scattering by elastic waves with significantly elevated acoustic losses. These features can be observed simpler in uniaxial, tetragonal, and trigonal crystals possessing linear acoustic attenuation. We demonstrate that formerly studied additional degree of freedom, revealed initially for multi-phonon regimes of acousto-optical interaction, can be identified within the one-phonon geometry as well and exploited for designing new cells. We clarify the role of varying the central acoustic frequency and acoustic attenuation using the identified degree of freedom. Therewith, we are strongly restricted by a linear regime of acousto-optical interaction to avoid the origin of multi-phonon processes within carrying out a multi-frequency parallel spectrum analysis of radio-wave signals. Proof-of-principle experiments confirm the developed approaches and illustrate their applicability to innovative technique for an advanced spectrum analysis of wideband radio-wave signals with the improved resolution in an extended frequency range.

We present a principally new acousto-optical cell providing an advanced wideband spectrum analysis of ultra-high frequency radio-wave signals. For the first time, we apply a recently developed approach with the tilt angle to a one-phonon non-collinear anomalous light scattering. In contrast to earlier cases, now one can exploit a regime with the fixed optical wavelength for processing a great number of acoustic frequencies simultaneously in the linear regime. The chosen rutile-crystal combines a moderate acoustic velocity with low acoustic attenuation and allows us wide-band data processing within GHz-frequency acoustic waves. We have created and experimentally tested a 6-cm aperture rutile-made acousto-optical cell providing the central frequency 2.0 GHz, frequency bandwidth ∼0.52 GHz with the frequency resolution about 68.3 kHz, and ∼7620 resolvable spots. A similar cell permits designing an advanced ultra-high-frequency arm within a recently developed multi-band radio-wave acousto-optical spectrometer for astrophysical studies. This spectrometer is intended to operate with a few parallel optical arms for processing the multi-frequency data flows within astrophysical observations. Keeping all the instrument's advantages of the previous schematic arrangement, now one can create the highest-frequency arm using the developed rutile-based acousto-optical cell. It permits optimizing the performances inherent in that arm via regulation of both the central frequency and the frequency bandwidth for spectrum analysis.

The Guillermo Haro astrophysical observatory (Mexico) realizes investigations in the visible and near-infrared range . Actually, the classical grating spectrometer with mechanically removable optical filters and diffraction gratings is exploited there. Unfortunately, the regular process of changing the diffraction gratings with different resolutions and recalibrating the spectrometer is inconvenient and wastes expensive time for observations. This is why exploiting an acousto-optical cell as a dynamic dispersive element is practically desirable, because potentially it realizes tuning the spectral resolution and the range of observation electronically and excludes filters. Some aspects of inserting just one dynamic acousto-optical diffraction grating instead of a set of the traditional static diffraction gratings are preliminarily considered.