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DOAJ Open Access 2026
A Rare and Interesting Case of Sciatic Nerve Compression Due to Proximal Femoral Osteochondroma in a Young Adult – A Case Report

Ninad Kishor Honwadkar, Eknath Deosing Pawar, Abhiram T V et al.

Introduction: Osteochondromas (OCs) are benign hamartomatous lesions composed of cartilage and bone, arising from aberrant growth-plate cartilage. They characteristically project from the bone surface through the cortex and grow by endochondral ossification beneath the periosteum. Lesion growth usually parallels skeletal growth and typically ceases after physeal closure, although minimal growth of the cartilage cap may persist and generally stops by the third decade of life. This developmental mechanism explains the predilection for involvement of the distal femur, proximal tibia, and proximal humerus. Most OCs are asymptomatic and do not require surgical intervention. However, intra-articular or atypically located lesions may produce pain, restricted joint movement, or compression of adjacent neurovascular structures, necessitating operative management. Case Report: A 39-year-old male presented to the outpatient department with complaints of left-sided hip pain associated with restricted range of motion and radiating pain along the posterior aspect of the left thigh, accompanied by buttock pain for 6 months. The symptoms had gradually progressed and were aggravated by activity. The patient also reported mild paresthesia over the anteromedial aspect of the left knee and the dorsum of the left foot. He noticed a gradually enlarging, ill-defined mass in the left gluteal region during the same period. On clinical examination, a firm, immobile mass measuring approximately 10 × 6 cm was palpated in the left buttock. Left hip flexion was limited to 60° due to pain. Neurological examination revealed weakness of both plantar flexion and dorsiflexion of the left ankle. The patient had previously received conservative treatment, including rest, non-steroidal anti-inflammatory drugs, and physiotherapy at another institution, with no improvement in symptoms. Results: The lesion was excised through a posterior approach with the patient positioned in the right lateral decubitus position, as described by Yu et al. The sciatic nerve was identified, carefully dissected, and protected throughout the procedure. The OCs were excised using an osteotome. Intraoperative assessment of the femoral neck revealed no cortical defects or fractures, and no fixation was required. Histopathological examination confirmed the diagnosis of OCs with a cartilaginous cap measuring <1 cm. Conclusion: Sciatic nerve compression symptoms in non-traumatic cases in young adults may result due to intra or extraspinal causes, depending on the anatomical site of involvement. Lumbar intervertebral disc prolapse and spinal canal stenosis constitute the most frequent intraspinal causes. Extraspinal etiologies are comparatively rare and include conditions such as piriformis syndrome and pelvic bone lesions. Benign bone tumors, particularly OCs, though uncommon, should be considered as a potential source of sciatic nerve compression. OCs arising from the femoral neck with intra-articular or posterior extension are rare, particularly in adults, and may present with pain, mechanical restriction of movement, and neurological symptoms due to mass effect. Awareness of such atypical presentations is essential to avoid misdiagnosis and delays in appropriate management.

Orthopedic surgery, Diseases of the musculoskeletal system
DOAJ Open Access 2026
Outcomes of supra-versus infra-renal clamping in elective open aortic aneurysm repair in a tertiary vascular center

Daniel Becker, MD, Ahmed Ali, MD, Anja Lehmann, MD et al.

Objective: Juxtarenal abdominal aortic aneurysms (AAAs), pose a greater surgical challenge than infrarenal AAAs and often require suprarenal aortic clamping during open repair. This study aims to assess the impact of suprarenal vs infrarenal clamping on short- and long-term renal outcomes, mortality, and reintervention rates. Methods: A retrospective cohort analysis was conducted on 1250 patients undergoing open AAA repair between 2000 and 2020 at a tertiary vascular center. Patients were stratified into suprarenal and infrarenal clamping groups. Outcomes included 30-day mortality, major adverse events, acute kidney injury, new-onset dialysis, chronic kidney disease (CKD), long-term mortality, and reintervention. Propensity score matching and multivariate analysis were used to adjust for confounders. Results: Of the cohort, 492 underwent suprarenal and 758 infrarenal clamping. The suprarenal group experienced higher 30-day major adverse events (20.9% vs 16.2%; P = .036), acute kidney injury (37.6% vs 22.0%; P < .001), and new-onset dialysis (4.5% vs 1.8%; P = .009). At a median follow-up of 8.6 years, CKD incidence was significantly higher in the suprarenal group (28.5% vs 21.1%; P = .004), as was all-cause mortality (41.3% vs 32.4%; P < .001). We found no difference in reintervention rates between groups. In the propensity-matched cohort, CKD remained significantly more common with suprarenal clamping (P < .001), whereas differences in mortality were not statistically significant. Conclusions: Suprarenal clamping during open AAA repair is associated with increased postoperative renal complications and long-term CKD and mortality, despite similar reintervention and short-term mortality rates. These findings support the need for individualized surgical planning.

Diseases of the circulatory (Cardiovascular) system, Surgery
DOAJ Open Access 2025
Bone Health Assessment and Management among Survivors of Non-metastatic Breast Cancer: A Narrative Review

Rebecca John, Kripa E. Cherian, Patricia Sebastian et al.

Breast cancer, the most common hormone responsive cancer, is on a rise both globally and in India. With increased longevity of breast cancer survivors, addressing long-term complications such as osteoporosis is crucial. Several mechanisms contribute to the bone loss seen in breast cancer patients, including age, post-menopausal status, chemotherapy, and other adjuvant therapies received. Appropriate evaluation and counselling on the risks of therapy with aromatase inhibitors on bone health are much needed. Timely initiation of anti-resorptive medication can help improve bone mass, reduce the incidence of fractures, and improve quality of life.

Diseases of the endocrine glands. Clinical endocrinology, Diseases of the digestive system. Gastroenterology
DOAJ Open Access 2025
A follow-up study of blood donors with vasovagal reaction – Three years’ experience

Shivanand Hemant Kumatagi, J. Akash, Vinu Rajendran et al.

AIM: The aim of this study was to find out the incidence of seizure recurrence among blood donors who developed vasovagal reaction (VVR). SETTINGS AND DESIGN: A prospective survey-based study conducted at the department of transfusion medicine of a tertiary care referral hospital in southern India. SUBJECTS AND METHODS: All donors who were diagnosed with VVR and loss of consciousness with or without convulsions during 3½ years study period were telephonically contacted to a maximum of 3 times. Whether they experienced a repeat episode of convulsions during 6-month follow-up period irrespective of blood donation was enquired. RESULTS: Out of 66 donors who were included in the study, 45 (68%) donors could be successfully contacted. One donor out of 45 (2.22%) had developed a repeat episode of seizure 5 months postdonation. However, she also had a previous history of seizures which was not revealed during the medical examination. CONCLUSIONS: Our study shows that the VVR with convulsions during blood donation can trigger a secondary episode if the donor had convulsions in their past before donation. We did not find any donor who developed a new seizure episode without a past history of seizure. However, more studies are needed to confirm the same.

Diseases of the blood and blood-forming organs
arXiv Open Access 2025
On the simultaneous recovery of boundary impedance and internal conductivity

Jinchao Pan, Jijun Liu

Consider an inverse problem of the simultaneous recovery of boundary impedance and internal conductivity in the electrical impedance tomography (EIT) model using local internal measurement data, which is governed by a boundary value problem for an elliptic equation in divergence form with Robin boundary condition. We firstly express the solution to the forward problem by volume and surface potentials in terms of the Levi function. Then, for the inverse problem, we prove the uniqueness of the solution in an admissible set by unique extension of the solution under some {a-prior} assumption. Finally we establish the regularizing reconstruction schemes for boundary impedance and internal conductivity using noisy measurement data with rigorous error estimates. The mollification method is proposed to recover the boundary impedance from the boundary condition, and the internal conductivity with known boundary value is recovered from an integral system, where the Tikhonov regularization is applied to seek the stable solution, considering that the error involved in the boundary impedance coefficient reconstruction will propagate to the recovering process for internal conductivity. Numerical implementations are presented to illustrate the validity of the proposed method.

en math.AP
DOAJ Open Access 2024
Objective assessment of docking site consolidation in bone transport: the role of pixel value ratio in predicting healing outcomes

Xin Yang, Yimurang Hamiti, Kai Liu et al.

Abstract Background The management of docking site healing in bone transport remains a significant challenge in orthopedic surgery. Traditional assessment methods rely heavily on qualitative radiographic evaluations. This study investigates the utility of pixel value ratio (PVR), an objective quantitative measure, in assessing bone healing at the docking site during bone transport. Methods This retrospective study included 47 patients who underwent bone transport for lower limb reconstruction between January 2015 and January 2020. Patients were categorized into bone union (n = 35) and nonunion (n = 12) groups based on docking site outcomes. PVR was calculated using two methods (PVR1 and PVR2) at six time points over 24 months post-docking. Subgroup analyses were performed based on gender, age, and surgical site. Results Of 47 patients, 35 achieved bone union and 12 experienced nonunion. Both PVR1 and PVR2 were consistently lower in the union group compared to the nonunion group at all time points (p < 0.001). In the union group, PVR1 ranged from 1.064 ± 0.050 to 1.108 ± 0.062, while PVR2 ranged from 0.926 ± 0.079 to 0.946 ± 0.062. In the nonunion group, PVR1 ranged from 1.204 ± 0.057 to 1.273 ± 0.020, and PVR2 from 1.039 ± 0.060 to 1.148 ± 0.022. Subgroup analyses revealed that males had significantly lower PVR values compared to females, and tibial cases had lower PVR values compared to femoral cases in both union and nonunion groups (p < 0.05). All juvenile patients achieved union, compared to 71.4% of adults (p < 0.01). Conclusion PVR demonstrates significant potential as an objective tool for assessing docking site healing in bone transport procedures. The distinct patterns observed between union and nonunion cases provide a foundation for developing clinical guidelines to monitor and predict healing outcomes. Integration of PVR assessment into clinical practice could improve decision-making and optimize treatment protocols in bone transport procedures.

Orthopedic surgery, Diseases of the musculoskeletal system
arXiv Open Access 2024
Operators in the Internal Space and Locality

Hardik Bohra, Sumit R. Das, Gautam Mandal et al.

Realizations of the holographic correspondence in String/M theory typically involve spacetimes of the form $AdS \times Y$ where $Y$ is some internal space which geometrizes an internal symmetry of the dual field theory, hereafter referred to as an "$R$ symmetry". It has been speculated that areas of Ryu-Takayanagi surfaces anchored on the boundary of a subregion of $Y$, and smeared over the base space of the dual field theory, quantify entanglement of internal degrees of freedom. A natural candidate for the corresponding operators are linear combinations of operators with definite $R$ charge with coefficients given by the "spherical harmonics'' of the internal space: this is natural when the product spaces appear as IR geometries of higher dimensional AdS spaces. We study clustering properties of such operators both for pure $AdS \times Y$ and for flow geometries, where $AdS \times Y$ arises in the IR from a different spacetime in the UV, for example higher dimensional AdS or asymptotically flat spacetime. We show, in complete generality, that the two point functions of such operators separated along the internal space obey clustering properties at scales larger than the $AdS$ scale. For non-compact $Y$, this provides a notion of approximate locality. When $Y$ is compact, clustering happens only when the size of $Y$ is parametrically larger than the $AdS$ scale. This latter situation is realized in flow geometries where the product spaces arise in the IR from an asymptotically AdS geometry at UV, but not typically when they arise near black hole horizons in asymptotically flat spacetimes. We discuss the significance of this result for entanglement and comment on the role of color degrees of freedom.

en hep-th
DOAJ Open Access 2023
Transcriptome analysis identification of A-to-I RNA editing in granulosa cells associated with PCOS

Fan-Sheng Kong, Fan-Sheng Kong, Zijing Lu et al.

BackgroundPolycystic ovary syndrome (PCOS) is a complex, multifactor disorder in women of reproductive age worldwide. Although RNA editing may contribute to a variety of diseases, its role in PCOS remains unclear.MethodsA discovery RNA-Seq dataset was obtained from the NCBI Gene Expression Omnibus database of granulosa cells from women with PCOS and women without PCOS (controls). A validation RNA-Seq dataset downloaded from the European Nucleotide Archive Databank was used to validate differential editing. Transcriptome-wide investigation was conducted to analyze adenosine-to-inosine (A-to-I) RNA editing in PCOS and control samples.ResultsA total of 17,395 high-confidence A-to-I RNA editing sites were identified in 3,644 genes in all GC samples. As for differential RNA editing, there were 545 differential RNA editing (DRE) sites in 259 genes with Nucleoporin 43 (NUP43), Retinoblastoma Binding Protein 4 (RBBP4), and leckstrin homology-like domain family A member 1 (PHLDA) showing the most significant three 3′-untranslated region (3′UTR) editing. Furthermore, we identified 20 DRE sites that demonstrated a significant correlation between editing levels and gene expression levels. Notably, MIR193b-365a Host Gene (MIR193BHG) and Hook Microtubule Tethering Protein 3 (HOOK3) exhibited significant differential expression between PCOS and controls. Functional enrichment analysis showed that these 259 differentially edited genes were mainly related to apoptosis and necroptosis pathways. RNA binding protein (RBP) analysis revealed that RNA Binding Motif Protein 45 (RBM45) was predicted as the most frequent RBP binding with RNA editing sites. Additionally, we observed a correlation between editing levels of differential editing sites and the expression level of the RNA editing enzyme Adenosine Deaminase RNA Specific B1 (ADARB1). Moreover, the existence of 55 common differentially edited genes and nine differential editing sites were confirmed in the validation dataset.ConclusionOur current study highlighted the potential role of RNA editing in the pathophysiology of PCOS as an epigenetic process. These findings could provide valuable insights into the development of more targeted and effective treatment options for PCOS.

Diseases of the endocrine glands. Clinical endocrinology
DOAJ Open Access 2022
Evaluation of Oxidative Stress and Inflammatory Biomarkers Pre and Post-Treatment in New Diagnosed Atherosclerotic Patients

Ahmet Belce, Beyza Nur Ozkan, Fatma Sena Dumlu et al.

Atherosclerosis is a chronic vascular inflammatory disease associated to oxidative stress and endothelial dysfunction. It is characterized by lipid accumulation in the arterial wall, increased hyperlipidemia, oxidative stress, lipid peroxidation, and protein oxidation. Our study included 45 patients ages of 40–60 and 45 healthy volunteers with similar demographic characteristics without any chronic disease as well. Fasting plasma glucose, BUN, creatinine, LDL-cholesterol, HDL-cholesterol, triglyceride, total cholesterol, HbA1c, and C-reactive protein (CRP) levels were measured using commercial kits by autoanalyzer. The oxidative stress biomarkers total oxidant status (TOS), total antioxidant status (TAS), total thiol (TT), native thiol (NT), catalase (CAT), paraoxonase (PON1), and arylesterase (ARES) enzyme activities were measured using photometric methods. The inflammatory biomarkers interleukin 1 beta (IL-1β), tumor necrosis factor-α (TNF-α), presepsin (PSPN), and raftlin (RFTN1) levels were measured with ELISA Kits. Oxidative stress index (OSI) and disulfide (DIS) were calculated. The clinical, biochemical biomarkers such as BUN, creatinine, HDL, LDL, total cholesterol, triglyceride, and CRP levels were found to be higher than the control group and lower post-treatment compared to the pre-treatment group (p <0.001). The oxidative stress parameters, TOS, OSI, and DIS levels were found to be higher than the control group, and the levels before the treatment were statistically significantly higher than after the treatment (p < 0.001). Antioxidant biomarkers TAS, TT, and NT levels were low in the patient group. Inflammatory biomarkers were highest before treatment and decreased with treatment. Oxidative stress and inflammation, which increased in atherosclerosis patients may guide disease prognosis and treatment strategies.

Diseases of the circulatory (Cardiovascular) system
DOAJ Open Access 2022
Levels of Pathogenic Th17 and Th22 Cells in Patients with Rheumatoid Arthritis

Marlen Vitales-Noyola, Berenice Hernández-Castro, Diana Alvarado-Hernández et al.

Rheumatoid arthritis (RA) is a chronic autoimmune condition characterized, among others, by tissue damage and activation/differentiation of proinflammatory lymphocytes. Accordingly, several studies have concluded that type 17 T helper (Th17) cells seem to have an important role in the pathogenesis of this condition. However, the strategy for the identification and analysis of proinflammatory Th17 cells in those studies has not been consistent and has usually been different from what was originally described. Therefore, we decided to evaluate the levels of Th17 cells in patients with RA employing an extended immune phenotype by using an eight-color multiparametric flow cytometry analysis. For this purpose, blood samples were obtained from 30 patients with RA and 16 healthy subjects, and the levels of Th17 and type 22 helper (Th22) lymphocytes were analyzed as well as the in vitro differentiation of peripheral blood mononuclear cells into Th17 lymphocytes induced by interleukin-23 (IL-23) and IL-1β. We found significant enhanced levels of total Th17 lymphocytes (defined as CD4+IL-17+) as well as enhanced numbers of their pathogenic (defined as CD4+CXCR3+IL-17+IL-22+CD243+CD161+IFN-γ+IL-10-) and nonpathogenic (CD4+CXCR3+IL-17+IL-22-CD243-CD161-IFN-γ-IL-10+) cell subsets in patients with RA. Likewise, the number of Th22 (CD4+CXCR3+/-IL-17-IL-22+) was also increased in these patients compared to healthy controls. However, the in vitro induction/differentiation of pathogenic Th17 cells showed similar results in controls and patients with RA. Likewise, no significant associations were detected in patients with RA between the levels of Th17 or Th22 cells and clinical or laboratory parameters. Our data indicate that patients with RA show enhanced blood levels of the different subsets of Th17 cells and Th22 lymphocytes tested in this study and suggest that these levels are not apparently associated with clinical or laboratory parameters.

Immunologic diseases. Allergy
DOAJ Open Access 2022
Nucleocapsid mutations in SARS-CoV-2 augment replication and pathogenesis.

Bryan A Johnson, Yiyang Zhou, Kumari G Lokugamage et al.

While SARS-CoV-2 continues to adapt for human infection and transmission, genetic variation outside of the spike gene remains largely unexplored. This study investigates a highly variable region at residues 203-205 in the SARS-CoV-2 nucleocapsid protein. Recreating a mutation found in the alpha and omicron variants in an early pandemic (WA-1) background, we find that the R203K+G204R mutation is sufficient to enhance replication, fitness, and pathogenesis of SARS-CoV-2. The R203K+G204R mutant corresponds with increased viral RNA and protein both in vitro and in vivo. Importantly, the R203K+G204R mutation increases nucleocapsid phosphorylation and confers resistance to inhibition of the GSK-3 kinase, providing a molecular basis for increased virus replication. Notably, analogous alanine substitutions at positions 203+204 also increase SARS-CoV-2 replication and augment phosphorylation, suggesting that infection is enhanced through ablation of the ancestral 'RG' motif. Overall, these results demonstrate that variant mutations outside spike are key components in SARS-CoV-2's continued adaptation to human infection.

Immunologic diseases. Allergy, Biology (General)
arXiv Open Access 2022
The Effect of Internal Damping on Locomotion in Frictional Environments

Brian Van Stratum, Jonathan E. Clark, Kourosh Shoele

The gaits of undulating animals arise from a complex interaction of their central nervous system, muscle, connective tissue, bone, and environment. As a simplifying assumption, many previous studies have often assumed that sufficient internal force is available to produce observed kinematics, thus not focusing on quantifying the interconnection between muscle effort, body shape, and external reaction forces. This interplay, however, is critical to locomotion performance in crawling animals, especially when accompanied by body viscoelasticity. Moreover, in bio-inspired robotic applications, the body's internal damping is indeed a parameter that the designer can tune. Still, the effect of internal damping is not well understood. This study explores how internal damping affects the locomotion performance of a crawler with a continuous, visco-elastic, nonlinear beam model. Crawler muscle actuation is modeled as a traveling wave of bending moment propagating posteriorly along the body. Consistent with the friction properties of the scales of snakes and limbless lizards, environmental forces are modeled using anisotropic Coulomb friction. It is found that by varying the crawler body's internal damping, the crawler's performance can be altered, and distinct gaits could be achieved, including changing the net locomotion direction from forward to back. We will discuss this forward and backward control and identify the optimal internal damping for peak crawling speed.

en physics.bio-ph
DOAJ Open Access 2021
Modified high-flow nasal cannula oxygen therapy versus conventional oxygen therapy in patients undergoing bronchoscopy: a randomized clinical trial

Rui Wang, Hai-Chao Li, Xu-Yan Li et al.

Abstract Background Hypoxemia frequently occurs during bronchoscopy. High-flow nasal cannula (HFNC) oxygen therapy may be a feasible alternative to prevent the deterioration of gas exchange during bronchoscopy. With the convenience of clinical use in mind, we modified an HFNC using a single cannula. This clinical trial was designed to test the hypothesis that a modified HFNC would decrease the proportion of patients with a single moment of peripheral arterial oxygen saturation (SpO2) < 90% during bronchoscopy. Methods In this single-center, prospective randomized controlled trial, hospitalized patients in the respiratory department in need of diagnostic bronchoscopy were randomly assigned to a modified HFNC oxygen therapy group or a conventional oxygen therapy (COT) group. The primary outcome was the proportion of patients with a single moment of SpO2 < 90% during bronchoscopy. Results Eight hundred and twelve patients were randomized to the modified HFNC (n = 406) or COT (n = 406) group. Twenty-four patients were unable to cooperate or comply with bronchoscopy. Thus, 788 patients were included in the analysis. The proportion of patients with a single moment of SpO2 < 90% during bronchoscopy in the modified HFNC group was significantly lower than that in the COT group (12.5% vs. 28.8%, p < 0.001). There were no significant differences in the fraction of inspired oxygen between the two groups. The lowest SpO2 during bronchoscopy and 5 min after bronchoscopy in the modified HFNC group was significantly higher than that in the COT group. Multivariate analysis showed that a baseline forced vital capacity (FVC) < 2.7 L (OR, 0.276; 95% CI, 0.083–0.919, p = 0.036) and a volume of fluid instilled > 60 ml (OR, 1.034; 95% CI, 1.002–1.067, p = 0.036) were independent risk factors for hypoxemia during bronchoscopy in the modified HFNC group. Conclusions A modified HFNC could decrease the proportion of patients with a single moment of SpO2 < 90% during bronchoscopy. A lower baseline FVC and large-volume bronchoalveolar lavage may predict desaturation during bronchoscopy when using a modified HFNC. Trial registration ClinicalTrials. Gov: NCT02606188. Registered 17 November 2015.

Diseases of the respiratory system
arXiv Open Access 2021
Development of a GPU-accelerated Monte Carlo dose calculation module for nuclear medicine, ARCHER-NM: Demonstration for a PET/CT imaging procedure

Zhao Peng, Yu Lu, Yao Xu et al.

This paper describes the development and validation of a Monte Carlo (MC) dose computing module dedicated to organ dose calculations of patients undergoing nuclear medicine (NM) internal radiation exposures involving 18F-FDG PET/CT examination. This new module extends the more-than-10-years-long ARCHER project that developed a GPU-accelerated MC dose engine by adding dedicated NM source-definition features. To validate the code, we compared dose distributions from the 0.511-MeV point photon source calculated for a water phantom as well as a patient PET/CT phantom against a well-tested MC code, GATE. The water-phantom results show excellent agreement, suggesting that the radiation physics module in the new NM code is adequate. To demonstrate the clinical utility and advantage of ARCHER-NM, one set of PET/CT data for an adult male NM patient is calculated using the new code. Radiosensitive organs in the CT dataset are segmented using a CNN-based tool called DeepViewer. The PET image intensity maps are converted to radioactivity distributions to allow for MC radiation transport dose calculations at the voxel level. The dose rate maps and corresponding statistical uncertainties were calculated for the duration of PET image acquisition. The dose rate results of the 18F-FDG PET imaging patient show that ARCHER-NM's results agree very well with those of the GATE within 0.58% to 4.11%. Most impressively, ARCHER-NM obtains such results in less than 0.5 minutes while it takes GATE as much as 376 minutes. This is the first study presenting GPU-accelerated patient-specific MC internal radiation dose rate calculations for clinically realistic 18F-FDG PET/CT imaging cases involving auto-segmentation of whole-body PET/CT images. This study suggests that modern computing tools -- ARCHER-NM and DeepViewer -- are accurate and fast enough for routine internal dosimetry in NM clinics.

en physics.med-ph
arXiv Open Access 2021
Internally Hankel $k$-positive systems

Christian Grussler, Thiago B. Burghi, Somayeh Sojoudi

The classes of externally Hankel $k$-positive LTI systems and autonomous $k$-positive systems have recently been defined, and their properties and applications began to be explored using the framework of total positivity and variation diminishing operators. In this work, these two system classes are subsumed under a new class of internally Hankel $k$-positive systems, which we define as state-space LTI systems with $k$-positive controllability and observability operators. We show that internal Hankel $k$-positivity is a natural extension of the celebrated property of internal positivity ($k=1$), and we derive tractable conditions for verifying the cases $k> 1$ in the form of internal positivity of the first $k$ compound systems. As these conditions define a new positive realization problem, we also discuss geometric conditions for when a minimal internally Hankel $k$-positive realization exists. Finally, we use our results to establish a new framework for bounding the number of over- and undershoots in the step response of general LTI systems.

en math.OC, math.DS
S2 Open Access 2020
Timing and Predictors of Subspecialty Career Choice Among Internal Medicine Residents: A Retrospective Cohort Study.

Jingkun Yang, S. Singhal, Yingjie Weng et al.

Background Internal medicine residents face numerous career options after residency training. Little is known about when residents make their final career choice. Objective We assessed the timing and predictive factors of final career choices among internal medicine residents at graduation, including demographics, pre-residency career preferences, and rotation scheduling. Methods We conducted a retrospective study of graduates of an academic internal medicine residency program from 2014 to 2017. Main measures included demographics, rotation schedules, and self-reported career choices for residents at 5 time points: recruitment day, immediately after Match Day, end of postgraduate year 1 (PGY-1), end of PGY-2, and at graduation. Results Of the 138 residents eligible for the study, 5 were excluded based on participation in a fast-track program for an Accreditation Council for Graduate Medical Education subspecialty fellowship. Among the remaining 133 residents, 48 (36%) pursued general internal medicine fields and 78 (59%) pursued fellowship training. Career choices from recruitment day, Match Day, and PGY-1 were only weakly predictive of the career choice. Many choices demonstrated low concordance throughout training, and general medicine fields (primary care, hospital medicine) were frequently not decided until after PGY-2. Early clinical exposure to subspecialty rotations did not predict final career choice. Conclusions Early career choices before and during residency training may have low predictability toward final career choices upon graduation in internal medicine. These choices may continue to have low predictability beyond PGY-2 for many specialties. Early clinical exposure may not predict final career choice for subspecialties.

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