Dilated Convolution to Capture Scale Invariant Context in Crowd Density Estimation

Crowd Density Estimation (CDE) can be used ensure safety of crowds by preventing stampedes or reducing spread of disease which was made urgent with the rise of Covid-19. CDE a challenging problem due to problems such as occlusion and massive scale variations. This research looks to create, evaluate and compare different approaches to crowd counting focusing on the ability for dilated convolution to extract scale-invariant contextual information. In this work we build and train three different model architectures: a Convolutional Neural Network (CNN) without dilation, a CNN with dilation to capture context and a CNN with an Atrous Spatial Pyramid Pooling (ASPP) layer to capture scale-invariant contextual features. We train each architecture multiple times to ensure statistical significance and evaluate them using the Mean Squared Error (MSE), Mean Average Error (MAE) and Grid Average Mean Absolute Error (GAME) on the Shang-haiTech and UCF CC 50 datasets. Comparing the results between approaches we find that applying dilated convolution to more sparse crowd images with little scale variations does not make a significant difference but, on highly congested crowd images, dilated convolutions are more resilient to occlusion and perform better. Furthermore, we find that adding an ASPP layer improves performance in the case when there are significant differences in the scale of objects within the crowds. The code for this research is available at https://github.com/ThishenP/crowd-density. © 2022, EasyChair. All rights reserved.

IT'S ALWAYS COCAINE: A RARE CASE OF LEVAMISOLEINDUCED COCAINE ASSOCIATED VASCULITIS WITH PULMONARY AND RENAL INVOLVEMENT

CASE: 58 year old woman presents with 1 month of dyspnea and productive cough. She also reported loss of smell and hematuria for 1 week. History was notable for hypertension, COPD, substance abuse, specifically crack cocaine, and unstable housing. On admission she was tachypneic and hypoxic, requiring supplemental O2. Exam revealed bilateral crackles, elevated JVP, and mild lower extremity edema, but no skin changes or rashes. Laboratory studies showed an elevated creatine of 7.9. CT chest imaging showed extensive bilateral ground glass opacities with increased septal lines. Infectious work-up, including SARSCoV-2 PCR, was negative. Dialysis was initiated for new renal failure. To determine the etiology of the renal failure, autoimmune studies were obtained and showed a positive ANA and p-ANCA (1:640) and a negative MPO and PR3. Kidney biopsy was consistent with levamisole-induced vasculitis (LIV) from cocaine use. Treatment with steroids was initiated. She was discharged on steroid therapy and outpatient hemodialysis. She had repeated admissions for volume overload due to missed dialysis, and she developed heart failure within the year. She was unable to make appointments to start outpatient rituximab therapy. IMPACT/DISCUSSION: Levamisole-induced vasculitis (LIV) is a complication of use of cocaine adulterated with levamisole. Levamisole is an antihelminthic medication with well known immunomodulatory effects. Increasingly used as a cocaine adulterant, it is believed to be a component of over 80% of cocaine samples in the US. Its use is thought to be driven by levamisole's synergistic effect on the dopaminergic effects of cocaine. Levamisole-induced vasculitis is a p-ANCA associated vasculitis associated with long-term use of cocaine mixed with levamisole. It has been reported with both inhaled cocaine and smoking crack cocaine. Levamisole is thought to induce production of autoantibodies including p-ANCA, ANA, and lupus anticoagulant leading to immune complex deposition and secondary hypercoagulability. The most commonly reported presentation is cutaneous purpuric lesions, most notably the ear, tip of the nose, and malar eminence. LIV can occur without skin involvement and renal and pulmonary involvement including nephritis, renal failure, and hypersensitivity pneumonitis, has been reported. LIV with significant organ involvement is often treated with steroids. Additional immunosuppressive therapies including rituximab, cyclophosphamide, and plasmapheresis have been reported in severe cases. CONCLUSION: This case illustrates a rare presentation of LIV marked by with renal failure and absence of skin lesions. While the health effects of cocaine are well known, the adverse effects of agents used to cut cocaine are less readily considered. LIV should be considered in a patient with substance use disorder presenting with new vasculitis. As this case illustrates, factors like unstable housing and ongoing substance use disorder can complicate management.

DELAYED DECLINE: A CASE OF DELAYED POST-HYPOXIC LEUKOENCEPHALOPATHY

CASE: A 44 year old female with history of depression and recent suicide attempt presents with one week of cognitive and functional decline. One month prior to presentation, patient attempted suicide with opioids requiring intubation for respiratory depression and stroke sequelae. She was discharged from this stay after 12 days having returned to mental and functional baseline. Two weeks later, she demonstrated decreased focus and concentration, progressing to decreased mobility and akinesis, eventually presenting to our hospital. Admission metabolic and toxic workup was negative. CT head redemonstrated findings of previously known stroke. MRI demonstrated new increased T2 Flair of the parietal lobes and the cerebral white matter. LP was without evidence of infection or inflammation. Encephalitis panel and autoimmune workup were negative. Neurology consult suggested delayed post-hypoxic leukoencephalopathy as a possible diagnosis, given clinical course of improvement and subsequent decline, along with akinetic mutism and deep cortical white matter flair abnormalities. After failed trial of lorazepam, she was started on amantadine and her cognitive and functional status improved slowly. IMPACT/DISCUSSION: Delayed post-hypoxic leukoencephalopathy (DPHL) is a rare syndrome characterized by biphasic time course with initial recovery and subsequent cognitive and functional decline. DPHL can follow any event of prolonged cerebral hypoxia most frequently CO poisoning. It can occur with more common causes of hypoxia including overdose, cardiac arrest, and seizures;recent case reports have reported DPHL following severe covid infection. The clinical course involves a hypoxic event followed by a return to functional baseline typically lasting 7-21 days, after which progressive physical and mental decline occur. Signs include neuropsychiatric symptoms like amnesia and disorientation, as well as parkinsonism or akinetic mutism (1). The mechanism of DPHL is unclear. One possible mechanisms involves diffuse demyelination. The half life of myelin basic proteins is approximately 20 days, the length of the lucid interval. Hypoxia may abruptly halt the myelination process but symptoms may not emerge until a critical threshold of loss was achieved. Evaluation of DPHL involves considering other causes of encephalopathy, such as infection, substance use, stroke, catatonia, and toxins. In the absence of other causes, diagnosis of DPHL is based on characteristic time course following hypoxic event, symptoms, and MRI findings of diffuse T2 hyperintensity of cerebral white matter are pathognomonic (1). Treatment of DPHL is generally supportive. Limited evidence suggests amantadine may be of benefit. CONCLUSION: Physicians should consider DPHL in patients who have experienced cerebral hypoxia and present with the characteristic time course and imaging findings.

Pre-existing and post-covid-19 immune responses to sars-cov-2 in cancer patients

Cancer patients are at increased risk for critical illness upon COVID-19. We assessed antibody and T cell responses in unexposed and SARS-CoV-2 convalescent cancer patients to characterize SARS-CoV-2 immunity and to identify immunological parameters contributing to increased morbidity and mortality in COVID-19 cancer patients. Immune responses were assessed in unexposed (n = 199) and SARS-CoV-2-infected cancer patients (n = 17), comprising different hematological malignancies (HM) and solid tumor entities. T cell responses were assessed by IFN-g ELISPOT using previously defined cross-reactive and SARS-CoV-2-specific T cell epitopes (Nelde et al., Nat Immunol 2021). SARS-CoV-2 convalescents without cancer (n = 193) and unexposed healthy volunteers (HV, n = 94) served as reference groups. Whereas pre-existing SARS-CoV-2 cross-reactive CD4+ T cell responses were detectable in a high proportion of HV (78%) and solid tumor patients (77%), frequency was substantially lower in unexposed HM patients (34%). Concordantly, HM patients showed significantly higher proportions of CD4+ T cells expressing PD-1, LAG-3 and TIM-3, indicating T cell exhaustion as a potential underlying cause for the reduced T cell reactivity. In SARS-CoV-2 convalescents, no difference in antibody positivity was noted between cancer patients and HV. T cell response analyses showed comparable recognition frequencies of SARS-CoV-2-specific HLA class I and HLA-DR epitopes in both groups, whereas the frequency of HLA-DR cross-reactive T cell responses was significantly reduced in cancer patients. Again, this was attributable to a markedly reduced frequency of cross-reactive CD4+ T cell responses in HM patients. Analysis of T cell responses to single HLA-DR peptides (n = 20) after 12-day in vitro expansion further revealed reduced T cell expandability for 73% of SARS-CoV-2-derived peptides in COVID-19 cancer patients. Moreover, diversity of SARS-CoV-2 T cell responses (i.e. recognition of multiple different T cell epitopes) was significantly reduced in COVID-19 HM patients (20% recognized peptides) compared to solid tumor patients (35%) and HV (50%), and reduced T cell diversity was associated with a more severe course of COVID-19. In summary, our results identify impaired SARS-CoV-2 T cell immunity as a determinant for poor outcome of COVID-19 in cancer patients, particularly in HM. These findings guide the development of therapeutic measures and vaccines for this vulnerable patient population. Disclosure: Malte Roerden: No conflict of interest disclosed. Juliane S. Walz: Honoraria: Juliane S. Walz is listed as inventor for patents on peptides described in the research.;Expert Testimony: Bundesministerium für Bildung und Forschung (BMBF), German Cancer Consortium (DKTK), Deutsche Forschungsgemeinschaft (DFG), Wilhelm Sander Stiftung, José Carreras Leukämie-Stiftung, Fortüne-Programm der Universität Tübingen.

First Year Student Perception and Experience of Online Topographical Anatomy Laboratory Classes using Zoom Technology during the COVID-19 Pandemic

During semester one of 2020, the units ‘Functional Anatomy of the Trunk' and ‘Functional Anatomy of the Limbs' which focus on human topographical anatomy were re-designed into an online delivery format and taught remotely in response to the COVID-19 lockdown. It was expected that the move to remote teaching would negatively impact student perception and learning experience, in particular that of the cadaver-based laboratory work. The aim of this study was to investigate whether the replacement of traditional face-to-face cadaver-based anatomy laboratories with an online version using digital anatomy resources and Zoom technology as the communication platform would achieve comparable student learning experience and outcomes. First Year Students (n=69) enrolled in these units were invited to participate in this study and were asked at the conclusion of each unit to complete an anonymous opinion-based survey via Qualtrics. The Qualtrics data, student grades and Learning Management System (LMS) statistics were analysed. Results indicate that student perception of the online gross anatomy laboratory learning was positive and that it had complemented their learning. Most students agreed that as a visual learning resource, it provided an improved understanding of anatomy and helped with the application of anatomical knowledge. Interestingly, student performance showed a similar range of marks compared with previous years. However, students strongly agreed that the online 2D learning experience had significant limitations when compared to live use of cadavers in laboratories. © 2021. All Rights Reserved.

[COVID-19-associated hyperinflammatory state in a 15-year-old female patient]

Paediatric Multisystem Inflammatory Syndrome Temporally Related to SARS-CoV-2 (PIMS-TS) is a rare novel clinical entity observed in children and adolescents with evidence of a recent COVID-19 infection, and is characterized by a marked hyperinflammatory state with involvement of multiple organ systems.We report a case of a previously healthy 15-year-old female patient, who was admitted to paediatric intensive care with cardiac failure and was subsequently shown to have positive COVID-19 serology. The presenting symptoms were fever, cough, chest pain and gastro-intestinal symptoms. She was supported with milrinone and a low dose of vasopressors. Her hyperinflammatory state was treated with intravenous immunoglobulins, high dose aspirin and high-dose methylprednisolone. PIMS-TS is a rare, potentially life threatening novel clinical entity in children and adolescents with evidence of a COVID-19 infection. Clinicians need to be aware of the possibility of this new disease, to ensure prompt recognition and treatment.