Online Makespan Minimization with Parallel Schedules

In online makespan minimization a sequence of jobs $\sigma = J_1,..., J_n$ has to be scheduled on $m$ identical parallel machines so as to minimize the maximum completion time of any job. We investigate the problem with an essentially new model of resource augmentation. Here, an online algorithm is allowed to build several schedules in parallel while processing $\sigma$. At the end of the scheduling process the best schedule is selected. This model can be viewed as providing an online algorithm with extra space, which is invested to maintain multiple solutions. The setting is of particular interest in parallel processing environments where each processor can maintain a single or a small set of solutions. We develop a (4/3+\eps)-competitive algorithm, for any 0<\eps\leq 1, that uses a number of 1/\eps^{O(\log (1/\eps))} schedules. We also give a (1+\eps)-competitive algorithm, for any 0<\eps\leq 1, that builds a polynomial number of (m/\eps)^{O(\log (1/\eps) / \eps)} schedules. This value depends on $m$ but is independent of the input $\sigma$. The performance guarantees are nearly best possible. We show that any algorithm that achieves a competitiveness smaller than 4/3 must construct $\Omega(m)$ schedules. Our algorithms make use of novel guessing schemes that (1) predict the optimum makespan of a job sequence $\sigma$ to within a factor of 1+\eps and (2) guess the job processing times and their frequencies in $\sigma$. In (2) we have to sparsify the universe of all guesses so as to reduce the number of schedules to a constant. The competitive ratios achieved using parallel schedules are considerably smaller than those in the standard problem without resource augmentation

POS0433 CAN INTERLEUKIN 33 (IL-33) BE CONSIDERED A VALUABLE BIOMARKER IN THE EARLY STAGES OF SYSTEMIC SCLEROSIS? ANALYSIS OF A MONOCENTRIC COHORT

Background:The ScS approach has changed considerably in recent years especially concerning the very early diagnosis of the disease (VEDOSS) at the time when the patient is still in an undifferentiated form (UCTD) at risk of developing SSc (1, 2). Of great value are different clinical, instrumental and laboratory findings, such as specific autoantibodies and Nailfold VideoCapillaroscopy (NVC), able to identify those cases progressing into overt SSc. IL-33 cytokine is known to exert pro-fibrotic effects through its membrane receptor ST2 on immune cells and myofibroblasts and recent studies suggest that it can be released following endothelial cell activation at the onset of SSc (3, 4).Objectives:Our aim has been to evaluate IL-33 serum levels in a monocentric cohort of VEDOSS patients, looking for the possible association with clinical phenotype and disease progression, focusing on the microvascular capillaroscopic changes.Methods:Fourty-seven VEDOSS patients underwent a complete clinical, instrumental and laboratory evaluation, including NVC and specific SSc autoantibodies. At baseline serum IL-33 levels were measured using an ELISA assay. In 32 of them we also had a second serum sample at a follow-up time of at least 24 months (range 24 to 96 months).Results:During the follow-up time, 17 patients were subsequently reclassified as having ScS whereas 30 remained VEDOSS. The "progressor" subjects positively correlated with the presence of anti-Topoisomerase I antibodies (p>0,004). IL-33 concentrations had a median value of 427.2 pg/ml (IQR 967.9 pg/ml) at baseline and of 130.4 pg/ml (IQR 399 pg/ml) at the follow up, showing a statistically significant difference independently from the progression of the disease (p=0.03). Besides significantly higher levels were detected in those patients with more severe NVC changes, defined as "active" pattern (p<0.05). Among the 47 VEDOSS patients, 12 started some kind of vascular therapy. In these patients serum IL-33 concentrations significantly lowered during the follow-up respect to those without any treatment (p<0.03)Conclusion:The analysis of our data confirms previous report (5) on higher IL-33 serum levels in the very early stages of UCTD patients at risk for SSc, regardless of their progression in established SSc, although related to more severe microvascular NVC involvement. The lowering of IL-33 serum levels that we detected in the follow up of our patients, may be linked to the well-known endothelial changes during the progression of the SSc and seems also to be partially affected by treatments. Investigation on a greater number of patients are needed to better understand our findings.References:[1]J. Avouac et al. Ann Rheum Dis 2011[2]G Valentini et al. Clin Exp Med 2017[3]Manetti M, et al. Ann Rheum Dis 2010[4]Terras S et al. Ann Rheum Dis 2013[5]Vettori S, et al. J Clin Immunol 2014Disclosure of Interests:None declare

Role of unenhanced breast MRI for detecting and differentiating breast lesions

N. A

POS1185 IMPACT OF LOCKDOWN DURING COVID-19 PANDEMIC ON THE ONSET OF POST-TRAUMATIC STRESS DISORDER (PTSD) IN SYSTEMIC SCLEROSIS PATIENTS: A CASE-CONTROL STUDY

Background:Social distancing due to COVID-19 pandemic had a major impact on the mental health of general population, with a high prevalence of post-traumatic stress disorder (PTSD) related symptoms1, 2. Psychological repercussions were notably found in people with chronic diseases, including systemic sclerosis (SSc) patients, where an increasing of anxiety symptoms, related also to low financial resources, emerged3.Objectives:To evaluate the impact of COVID-19 lockdown on the onset of PTSD in patients with SSc, firstly during the total confinement period (March-April 2020) and then at the time of less restrictive government measures, following the RT index lowering (June-July 2020)4.Methods:We carried out a case-control study on 57 SSc patients, according to the ACR/EULAR 2013 criteria, and on 57 healthy subjects as control group (HC), matched by sex and age. At T0 (March-April) and T1 (June-July) both populations received the "Impact of Event Scale Revised" questionnaire (IES-R) by e-mail, with a cut-off of ≥ 33 defining probable diagnosis of PTSD5. A multivariate analysis of possible factors influencing IES-R score, such as age, number of cohabitating people and weekly outings count, was performed in SSc patients at both times of the survey.Results:At T0 we found a significantly greater number of SSc patients with IES-R score ≥ 33 compared to HC (26/45.6% vs 13/22.8%; median value [quartiles] 31 [19.5;42.5] vs 24 [15.5; 32]; p-value 0.046). At T1, we obtained data from 44 SSc patients and 35 HC but no significant difference was noticed (18 / 40.9% vs 8 / 23.5%; 26 [15.25; 38] vs 26.5 [20.75; 32.5]; p> 0.05). SSc patients also had significantly fewer weekly outings than HC, both at T0 (p <0.001) and T1 (p <0.001) (Table 1). The multivariate analysis performed at T0 on SSc patients showed a significant association of IES-R ≥33 score with age (p 0.025) and with a lower count of weekly outings (p 0.002). The latter data negatively correlated with an IES-R ≥33 score in SSc patients (r -0.267, p 0.004).Conclusion:We found a significantly higher prevalence of PTSD in SSc patients compared to HC at the strictest lockdown time, turning into comparable when government measures were less restrictive, due to the minimum RT index values recorded in Italy. Older age and lower count of weekly outings were associated with PTSD in SSc patients during the lockdown, whereas the count of weekly outings was lower than in HC during both the examined periods. The results of this study indicate that COVID-19 lockdown had a worse impact in SSc patients, where the fewer weekly outings may depend on their clinical condition and on a greater concern about their health6. These findings strengthen the World Scleroderma Foundation recommendations regarding care to the psychological frailty of SSc patients7.References:[1]Wang C, Brain Behav Immun. 2020.[2]Dubey S, Psychiatr Pol. 2020.[3]Thombs BD, J Psychosom Res. 2020 Dec.[4]https://covid19.infn.it/grafici/?chart=italia,rt,covidstat[5]Weiss, D. S., & Marmar, C. R. (1996). The Impact of Event Scale - Revised, Assessing. psychological trauma and PTSD (pp. 399-411).[6]Orlandi M, Clin Rheumatol. 2020[7]Matucci-Cerinic M, Ann Rheum Dis. 2020Table 1.Descriptive analysis of study population: T0 (Time 0), T1 (Time 1), SD (Standard Deviation), IES-R (Impact of Event Scale-Revised).SSc patient groupHS groupFemale:male ratio at T046:746:7Mean age ± SD at T059±12.851±8.7IES-R ≥33 score n°/% at T026/45.6%*13/22.8%IES-R ≥33 score n°/% at T118/40.9%8/23.5%IES-R score at T0, median value [quartiles]31 [19.5;42.5]24 [15.5;32]IES-R score at T1, median value [quartiles]26 [15.25; 38]26.5 [20.75; 32.5]N° of weekly outings at T0, median value [quartiles]2 [1;3.5]4 [2;10]**N° of weekly outings at T1, median value [quartiles]5 [3;6]14 [6.75;15]***p<0.046; **p<0.001Disclosure of Interests:None declared

Infrared Thermography in Symptomatic Knee Osteoarthritis: Joint Temperature Differs Based on Patient and Pain Characteristics

The aim of this study was to evaluate osteoarthritis (OA) patients with infrared thermography to investigate imaging patterns as well as demographic and clinical characteristics that influence knee inflammation. Forty patients with one-sided symptomatic knee OA were included and evaluated through knee-specific PROMs and the PainDETECT Questionnaire for neuropathic pain evaluation. Thermograms were captured using a thermographic camera FLIR-T1020 and temperatures were extracted using the software ResearchIR for the overall knee and the five ROIs: medial, lateral, medial patella, lateral patella, and suprapatellar. The mean temperature of the total knee was 31.9 ± 1.6 °C. It negatively correlated with age (rho = −0.380, p = 0.016) and positively correlated with BMI (rho = 0.421, p = 0.007) and the IKDC objective score (tau = 0.294, p = 0.016). Men had higher temperatures in the knee medial, lateral, and suprapatellar areas (p = 0.017, p = 0.019, p = 0.025, respectively). Patients with neuropathic pain had a lower temperature of the medial knee area (31.5 ± 1.0 vs. 32.3 ± 1.1, p = 0.042), with the total knee negatively correlating with PainDETECT (p = 0.045). This study demonstrated that the skin temperature of OA symptomatic knees is influenced by demographic and clinical characteristics of patients, with higher joint temperatures in younger male patients with higher BMI and worst objective knee scores and lower temperatures in patients affected by neuropathic pain

COVID-19 and systemic sclerosis: analysis of lifestyle changes during the SARS-CoV-2 pandemic in an Italian single-center cohort

The outbreak of SARS-CoV-2 has changed the habits and lives of people worldwide. Patients affected by systemic sclerosis (SSc) experienced constant fear because of their immunocompromised status. The aim of this study was to investigate the prevalence of SARS-CoV-2 infection and to analyze the lifestyle changes in a single-center cohort of SSc patients and if these changes were more severe than in the general population. During the Italian lockdown, we supplied two surveys to our 184 SSc patients. In the first one, filled by 110 patients, we asked if SARS-CoV-2 had infected them or if they experienced signs and symptoms consistent with COVID-19. The second survey, performed by 79 SSc patients and 63 healthy subjects, included questions about the lifestyle adopted during this specific period. Among our patients, COVID-19 was diagnosed only in one case, while three other subjects reported signs and symptoms suggestive for the disease. Regarding the second survey, our patients greatly changed their lifestyle during the pandemic, adopting more restrictive isolation measures, because of their awareness of frailty. To date, we do not dispose of enough data to speculate about the risk of COVID-19 among immunocompromised patients, although in our SSc patients their frailty seems to have been their shelter. Pending more accurate epidemiological studies, it is essential to share as much data as possible to better understand the impact of COVID-19 on SSc patients’ health.• The lifestyle adopted by SSc patients during the first months of COVID-19 pandemic was characterized by more stringent isolation rules than general population.• The prudential behavior of patients with SSc during Italian lockdown should be considered as a possible bias when analyzing the risk of SARS-CoV-2 disease in these subjects, as well as a protective factor against infection

Dynamic Collection Scheduling Using Remote Asset Monitoring: Case Study in the UK Charity Sector

Remote sensing technology is now coming onto the market in the waste collection sector. This technology allows waste and recycling receptacles to report their fill levels at regular intervals. This reporting enables collection schedules to be optimized dynamically to meet true servicing needs in a better way and so reduce transport costs and ensure that visits to clients are made in a timely fashion. This paper describes a real-life logistics problem faced by a leading UK charity that services its textile and book donation banks and its high street stores by using a common fleet of vehicles with various carrying capacities. Use of a common fleet gives rise to a vehicle routing problem in which visits to stores are on fixed days of the week with time window constraints and visits to banks (fitted with remote fill-monitoring technology) are made in a timely fashion so that the banks do not become full before collection. A tabu search algorithm was developed to provide vehicle routes for the next day of operation on the basis of the maximization of profit. A longer look-ahead period was not considered because donation rates to banks are highly variable. The algorithm included parameters that specified the minimum fill level (e.g., 50%) required to allow a visit to a bank and a penalty function used to encourage visits to banks that are becoming full. The results showed that the algorithm significantly reduced visits to banks and increased profit by up to 2.4%, with the best performance obtained when the donation rates were more variable