Vincent's University Hospital Research Articles

Gender Difference in sidE eFfects of ImmuNotherapy: a possible clue to optimize cancEr tReatment (G-DEFINER): study protocol of an observational prospective multicenter study.

Immune checkpoint inhibitors (ICIs) have significantly improved outcomes in various cancers. ICI treatment is associated with the incidence of immune-related adverse events (irAEs) which can affect any organ. Data on irAEs occurrence in relation to sex- differentiation and their association with gender-specific factors are limited. The primary objective of the G-DEFINER study is to compare the irAEs incidence in female and male patients who undergo ICI treatment. Secondary objectives are: to compare the irAEs incidence in pre- and postmenopausal female patients; to compare the irAEs incidence in female and male patients according to different clinical and gender-related factors (lifestyle, psychosocial, and behavioral factors). Exploratory objectives of the study are to compare and contrast hormonal, gene-expression, SNPs, cytokines, and gut microbiota profiles in relation to irAEs incidence in female and male patients. The patients are recruited from Fondazione IRCCS Istituto Nazionale dei Tumori, Italy, St Vincent's University Hospital, Ireland, Oslo University Hospital, Norway, and Karolinska Insitutet/Karolinska University Hospital, Sweden. The inclusion of patients was delayed due to the Covid pandemic, leading to a total of 250 patients recruited versus a planned number of 400 patients. Clinical and translational data will be analyzed. The expected outcomes are to improve the management of cancer patients treated with ICIs, leading to more personalized clinical approaches that consider potential toxicity profiles. The real world nature of the trial makes it highly applicable for timely irAEs diagnosis.

Trends in acute hospital smoking prevalence and support of campus ban in Dublin, Ireland (1997-2018)

Abstract Background St Vincent's University Hospital (SVUH), a major hospital in Dublin, Ireland pioneered a hospital smoke-free campus policy in 2009; pre/post this intervention it conducted periodic surveys of patients, staff & visitors for smoking prevalence and policy attitudes. As rates of smoking decline nationally in Ireland, it is important to monitor trends for at-risk groups, including lower socioeconomic status (SES). Methods Repeat questionnaires were administered by census surveys of inpatients, quota or random sub-sample surveys of staff, and quota surveys with outpatients and visitors between 1997 and 2018. As a proxy for social deprivation, the rate of inpatients eligible by income for the state-funded General Medical Services (GMS) card was assessed. Chi square test for trend and SPSS v.27 were used for analysis. Results Support for and awareness of the campus smoking ban increased steadily; post ban agreement varied by smoking status (64.7% smokers, 89.7% ex-smokers; 92.5% non-smokers, p = 0.002). Smoking rates declined in all groups but significantly in outpatients (19.5% vs. 10%; p < 0.01), visitors (27.4% vs 9.5%; p < 0.0001) and staff (30.0% vs 10.8%; p < 0.0001). Rates of inpatient GMS entitlement was high at 54.2% average, compared with national rates of approximately 30% in 2021. Rates of smoking were non-significantly higher in GMS entitled inpatients (33.2% vs 26.8%; p = 0.09) across all survey periods. Conclusions While hospital smoking prevalence has decreased and campus ban support persists, the campus is not immune to challenges in keeping it smoke-free. There are many socioeconomically deprived patients who smoke; this in part may reflect a private hospital on the same campus where affluent smokers are more likely to attend. Recent national initiatives for free nicotine replacement therapy and targeted smoking cessation courses in deprived areas work to address inequalities. We are not aware of similar studies in a hospital population over 25 years. Key messages • Periodic hospital smoking surveys show trends in prevalence which mirror the falling national trends in Ireland. • Socioeconomic differences persist in smoking rates among hospital patients.

Impact of antidepressant use on post-operative weight loss following bariatric surgery.

Antidepressant medication can be associated with weight gain. Consideration should be given to the specific agent prescribed to optimize bariatric surgery outcomes. The aim of this study is to investigate if patients treated with antidepressants stratified by risk of weight gain are associated with less weight loss at 1year postbariatric surgery. Asingle centre, retrospective analysis of all patients who underwent bariatric surgery between July 2018 and 2021 within St Vincent's University Hospital group. The exposure was antidepressant use, stratified for risk of weight gain, and the control group was patients who underwent surgery but no antidepressant use. The primary outcome was % TWL (total weight loss) at 6weeks, 6months and 12months post-surgery. Multivariate linear regression analysis was used to estimate the impact of antidepressant treatment on post-surgery weight loss at 12months using the variables of age, gender and pre-operative BMI. Of the total cohort (n = 315), 70 patients (22.2%) were taking antidepressants. At 12months, post-operatively patients taking medium risk for weight gain antidepressants had significantly less mean %TWL compared to those not taking antidepressants (p = 0.015). Overall, taking any antidepressant was not found to be a significant predictor of %TWL at 12months after surgery (β = - 2.590, p = 0.0836). Many patients undergoing bariatric surgery have concurrent psychiatric conditions. Given the complex relationship between bariatric surgery and mental health, psychotropic medications may be best managed by a specialist in the field such as a bariatric psychiatrist in order to optimize patient outcomes.

An Audit of Iron Deficiency in Hospitalised Heart Failure Patients: A Commonly Neglected Comorbidity.

Introduction Iron deficiency (ID) is a common comorbidity in patients with heart failure (HF) and can significantly impact morbidity and mortality, regardless of the presence of anaemia. Aim This audit aimed to assess the current practice in diagnosing and assessing iron deficiency (ID) in hospitalised patients with heart failure and reduced ejection fraction (HFrEF). The primary goal was to determine the prevalence of ID in HF patients and the frequency of iron testing in those patients. Additionally, the secondary aims included evaluating the presence of anaemia, the length of hospital stay, and the adequacy of appropriate management for iron deficiency in this patient population. Methods A retrospective audit was conducted, reviewing data from patients admitted to St. Vincent University Hospital over a period of 4 months. Results Out of the 111 patients audited, only74% (82)had their iron status checked, and among those tested, 63% (52) met the criteria for iron deficiency according to the European Society of Cardiology (ESC).Additionally, 54% (28) of iron-deficient patients were also anaemic. Iron replacement was administered to 34 out of the 52 patients diagnosed with iron deficiency, accounting for 65% of the identified cases. The average duration of hospital stay for patients with iron deficiency was 13.8 days, while those without iron deficiency had a shorter mean length of stay of 11.2 days. However, it is important to note that the presence of co-morbidities and other confounding factors might have influenced these results. Conclusion Despite guideline recommendations, iron deficiency remains under-recognised and undertreated in clinicalpractice among heart failure patients. There is a crucial need for increased awareness, education, and practical guidance to improve the screening, diagnosis, and management of iron deficiency in hospitalised heart failure patients.

Editorial introductions.

Editorial introductions.

Comparison between local and three validated triage systems in an emergency department for 2126 children under 3 months.

Triage of patients less than 3 months old was not already studied. The aim was to evaluate Paediatric Emergency Department triage in patients less than 3 months old and newborns using a local system in comparison with three validated paediatric triage systems (Canadian Triage and Acuity Scale, Manchester Triage System and Emergency Severity Index) and to determine inter-system agreement. All admissions of patients less than 3 months old admitted to the Emergency Department of the Saint Vincent University Hospital between April 2018 and December 2019 were included. The local triage system level was determined prospectively for comparison with retrospectively calculated triage levels of the validated systems. Hospitalisation rates were compared and inter-system agreements determined. Among emergency admissions, 2126 were included (55% males, mean age 45 days). Hospitalisation rate increased with priority severity as determined by all triage systems studied. Cohen's kappa showed slight agreement between the local triage system and the Canadian Triage and Acuity Scale, Emergency Severity Index and Manchester Triage System (weighted kappa = 0.133, 0.185 and 0.157 respectively). Whether prospective or retrospective triage used, the systems studied exhibited good association with hospitalisation rate for patients aged less than 3 months and newborn infants.

The association of centromere amplification and response to trastuzumab in HER2+ metastatic breast cancer.

1016 Background: Chromosomal instability and copy number aberration (CNA) burden can be associated with patients' survival in some cancers. Centromeres, chromosomal regions crucial for genomic stability, can be found altered by CNA in tumours but remain largely unexplored due to sequencing technologies. Using whole-genome sequencing (WGS) data from cases of long term, never relapsed HER2+ metastatic breast cancer (MBC) patients, also referred as exceptional responders (ExRs), we aim to better characterise the CNA profiles and underlying long-term survival of this “exceptional” cohort and investigate the centromeric and pericentromeric association with prognosis and treatment response. Methods: Two hundred and forty-three HER2+ MBC patients were enrolled in the HER2 Patients Project Database from St Vincent University Hospital, Dublin, Ireland. Eighty-five HER2+ MBC patients were identified as exceptional survivors (ExS) with an OS > 60 months (range 60-248 months), of which 28 never-relapsed and responded exceptionally (ExR) to trastuzumab. Patients with an OS < 60 months (N=158, range 0.2-59 months) were identified as non responders (NR). WGS was performed on 13 ExR tumours (primary or metastases) and matching control at a mean depth of 60X and 30X, respectively. Control-FREEC and CNVkit were used to characterise the CNA profiles and estimate the CNA burden. Samples from 10 NR patients were used for comparison with the ExR. Results: WGS analysis revealed that ExR samples are more impacted by gain rather than loss of copy overall, with a median fraction altered by gain of 0.24. No significant difference was observed between the ExR and NR in terms of CNA burden. However, a large fragment on chromosome 9 was amplified in 92% of ExR (12/13) which corresponded to the centromere (chr9q11) and a large heterochromatic block (chr9q12). A higher copy number status of this centromeric region was detected in the ExR, with a gain of at least 1 additional copy compared to the NR tumoral samples (P<0.001). The dichotomisation into high versus low copy number of the centromeric region of chromosome 9 was also observed in centromeres of chromosome 17 (P=0.009) and chromosome 19 (P<0.001). No case of polysomy was detected in our cohort and genes located near the centromeres, such as ERBB2 (amplified in both ExR and NR), were independent of the centromeres copy-number status. Conclusions: The identification of the genomic aberrations of these metastatic patients, treated with trastuzumab who never relapsed, increases our understanding of the mechanisms involved in MBC progression. Our results suggest that the centromere co-amplification of chr9q11-q12, chr17p11.1-q11.1 and chr19p11-q11 stratifies patients according to their OS. CNA status of the centromeric regions of chromosomes 9, 17 and 19 may therefore represent a novel prognostic predictor to trastuzumab response and new outcomes for patients.

Reducing the treatment burden of keratinocyte cancers requiring referral to plastic surgery: Lessons from lockdown

AbstractBackgroundKeratinocyte cancers are increasing in incidence in Ireland and are more common in older age, necessitating multidisciplinary specialist input and treatment often is a greater burden for patients. The coronavirus disease 2019 (COVID‐19) allowed us to restructure our interspecialty treatment pathways to reduce healthcare contact for patients.ObjectivesThe aim of this study was to establish whether a revised interspecialty pathway reduced the time‐to‐treatment completion (days) and treatment burden (defined as total healthcare encounter days).MethodsPatients with keratinocyte cancer under the care of dermatology and plastic surgery at St Vincent's University Hospital Dublin from July to December 2020 inclusive were identified in the Hospital‐Inpatient Enquiry database. Treatment burden was captured as the number of total days with a healthcare encounter and time‐to‐treatment completion was captured as the time from initial dermatology review to complete excision by plastic surgery.ResultsForty patients with 49 keratinocyte cancers were referred by dermatology to plastic surgery from July to December 2020. Thirty‐nine patients with 48 keratinocyte cancers were included in the analysis. The new referral pathway reduced the time‐to‐treatment completion from a mean of 164 to 75 days (p = 0.04). Treatment burden reduced from a mean of 5.4 to 3.5 (p = 0.002) total healthcare encounter days.ConclusionsMultidisciplinary input to establish a more efficient referral pathway for patients with keratinocyte cancer has successfully reduced the time‐to‐treatment completion and the treatment burden for our patients. This approach reduced the risk of exposure to COVID‐19 for patients and frees up valuable healthcare resources to treat these increasingly frequent malignancies.

HIV and co-morbidities - an evolving, global view.

aCentre for Experimental Pathogen Host Research, School of Medicine, University College Dublin bDepartment of Infectious Diseases, St Vincent's University Hospital, Dublin, Ireland Correspondence to Patrick W.G. Mallon, MBBS, PhD, University College Dublin, National University of Ireland, Dublin D4, Ireland. E-mail: [email protected]

Editorial introductions.

Editorial introductions.

Development of a coordinated acute diabetic foot pathway for management of acute diabetic foot infection and ulceration.

Diabetic foot ulceration (DFU) has become an increasingly common emergency presentation. These patients are presenting at a younger age and with increasingly complex co-morbidities. They require frequent hospitalisation for management of DFU which has significant consequences for management of health resources but also for quality of life in the diabetic patient population. The aim of this study was to evaluate the impact of the development of a coordinated, streamlined acute diabetic foot pathway for management of in-patients presenting as emergencies with DFU on length of stay, re-admission to hospital and minor and major amputations. A dedicated acute diabetic foot pathway was introduced to St. Vincent's University Hospital (SVUH) in April 2016. Management of patients admitted urgently to the emergency department or out-patient clinics of St. Vincent's University Hospital during the 3-year period before April 2016 was compared to that of patients admitted in the 3years after April 2016 following introduction of the acute diabetic foot pathway. Demographic data hospital length of stay, need for re-admission, major and minor amputations performed and cost of hospital stay were compared before and after introduction of the pathway. There were 931 admissions with acute diabetic foot ulceration or infection between January 2012 and December 2019; 419 were admitted between January 2012 and March 2016 and 512 between April 2016 and December 2019. There was no difference in demographic data between the two time periods. Length of stay decreased from 13 +/- 4.24 to 3 +/- 1.41days between the two time periods (p < 0.001). Re-admission rates within 30days decreased from 21.7 to 10.1% (p < 0.05). The number of major lower limb amputations decreased over the two time periods from 8.8 to 7.2% with a concomitant increase in minor amputations from 16.7 to 25.3%. Risk of major lower limb amputation was significantly higher in those patients living more than 20km from the hospital. Costs associated with in-patient stay for management of DFU decreased from €9,247,700 to €8,988,100 despite an 18% increase in the number of patients treated and a 9.9% increase in hospital admissions. Introduction of a dedicated, streamlined pathway involving multi-disciplinary input resulted in a significant improvement in patient management as assessed by length of hospital stay and need for re-admission. While the number of major lower limb amputations has decreased there has been a significant increase in the number of minor amputations.

Multimodal Multiresolution Data Fusion Using Convolutional Neural Networks for IoT Wearable Sensing.

With advances in circuit design and sensing technology, the acquisition of data from a large number of Internet of Things (IoT) sensors simultaneously to enable more accurate inferences has become mainstream. In this work, we propose a novel convolutional neural network (CNN) model for the fusion of multimodal and multiresolution data obtained from several sensors. The proposed model enables the fusion of multiresolution sensor data, without having to resort to padding/ resampling to correct for frequency resolution differences even when carrying out temporal inferences like high-resolution event detection. The performance of the proposed model is evaluated for sleep apnea event detection, by fusing three different sensor signals obtained from UCD St. Vincent University Hospital's sleep apnea database. The proposed model is generalizable and this is demonstrated by incremental performance improvements, proportional to the number of sensors used for fusion. A selective dropout technique is used to prevent overfitting of the model to any specific high-resolution input, and increase the robustness of fusion to signal corruption from any sensor source. A fusion model with electrocardiogram (ECG), Peripheral oxygen saturation signal (SpO2), and abdominal movement signal achieved an accuracy of 99.72% and a sensitivity of 98.98%. Energy per classification of the proposed fusion model was estimated to be approximately 5.61 μJ for on-chip implementation. The feasibility of pruning to reduce the complexity of the fusion models was also studied.

Integration of StopHF Model in Primary Healthcare System In Pakistan

Pakistani healthcare system consist of rural health centre (RHC), basic health unit (BHU) connected to district headquarter hospital which offer specialist services. RHC and BHU form the basis of primary care in Pakistan. There is another parallel private healthcare system which serve 70% of the population. Due to lack of facilities in primary healthcare system most of the population attends private healthcare. Private healthcare system serves 70% of the general population in Pakistan and most of the patients would prefer to attend private clinic and private hospitals for minor or major illnesses. These private clinic also serve a major part in primary prevention and management of cardiovascular diseases. Primary prevention plays an important role in management of cardiovascular disease. In STOP-HF first-of-its-type research study, the investigators recruited 1374 individuals with cardiovascular risk factors from a nurse-lead healthcare cardiovascular screening program in the catchment area of St. Vincent's University Hospital, Dublin, Ireland, between January 2005 to December 2009. This study demonstrated reduction in adverse cardiovascular events using BNP guided risk stratification of patients with cardiovascular risk factors. STOP-HF offers an excellent design to the global community on how to incorporate simple screening testing with secondary and tertiary healthcare system. Pakistani healthcare system can utilise STOP-HF model for the management of cardiovascular risk factor using BNP testing for identifying high risk population and early diagnosis and management of heart failure.

Editorial introductions

Editorial introductions

Prevalence and Impact of Atrial Fibrillation in a Cohort of Patients with Hypertrophic Cardiomyopathy in Ireland.

Atrial fibrillation (AF) is the most common sustained arrhythmia in patients with hypertrophic cardiomyopathy (HCM), and is associated with deterioration in clinical status and outcome. To date, no data have been published pertaining to AF in an Irish HCM population. 159 patients with HCM attending St Vincent's University Hospital and Blackrock Clinic, Dublin, were identified. Detailed review of medical notes, Holter monitor, echocardiogram, cardiac MRI (CMR) and implantable cardioverter-defibrillator (ICD) records was performed.Prevalence of AF was 38.4%. HCM patients with AF (HCM-AF) were older (60.6±14.8 v 54.9±17.3 years, P=0.016) and more symptomatic (NYHA II: 29.7% v 16.9%, NYHA III: 4.3% v 1.2%) than HCM patients without AF. History of stroke was recorded in 16.4% of HCM-AF patients, compared with 1% in those without AF.HCM-AF patients had lower left ventricular ejection fraction (echo: 59.5±11.8v68±8, P<0.001; CMR: 62.3%v70.5%, P<0.01) and higher left atrial diameter (echo: 49.8±9.5v40.9±7.4, p<0.001; CMR 62.3±11.3v70.4±9, p<0.001), compared with those without AF. Myocardial fibrosis was detected on CMR in 74% of HCM-AF patients and 62% of those without AF.34% of patients had an ICD in situ, of whom 61% had AF. 24% of these HCM-AF patients received inappropriate shocks, all triggered by AF. AF is common in the Irish HCM population. It is associated with increased risk of stroke, deterioration in symptom status and is a common trigger for inappropriate ICD discharge. We have shown, in-keeping with previous studies, that AF is associated with reduced EF, increased LA diameter and mitral regurgitation in this HCM population.

Lockdown logistics in consultation-liaison psychiatry.

We describe the adaptation of services to allow flexible and practical responses to the coronavirus-19 (COVID-19) public health crisis by four Consultation-Liaison Psychiatry (CLP) services; Galway University Hospital (GUH), Beaumont Hospital, University Hospital Waterford and St Vincent's University Hospital (SVUH) CLP services. This article also illustrates close collaboration with community adult mental health services and Emergency Department (ED) colleagues to implement effective community diversion pathways and develop safe, effective patient assessment pathways within the EDs. It highlights the high levels of activity within each of the CLP services, while also signposting that many of the rapidly implemented changes to our practice may herald improvements to mental health patient care delivery in the post-COVID-19 world, if our psychiatry services receive appropriate resources.

Abstract 1678: Establishment and characterization by expression microarrays of a patient-derived xenograft biobank for human pancreatic adenocarcinoma

Abstract Pancreatic cancer survival rate is poor, with a 5-year survival rate of 7% in the Republic of Ireland. Over the last 40 years, pancreatic cancer is one of the only solid tumor types to have minimal improvement in patient outcome. In Ireland, pancreatic cancer surgical resection is limited to two hospitals: Cork University Hospital and St Vincent's University Hospital (SVUH) in Dublin. In collaboration with SVUH, we have established Ireland's only pancreatic cancer patient-derived xenograft (PDX) biobank program. Tumor material from candidate patients following surgical resection was cold transferred and implanted subcutaneously into CB17/Icr-Prkdcscid mice. At time of implant and continuation of generations, snap frozen material was collected. Using miRNA and mRNA microarray technology, matched adjacent normal tissue, original tumor material and first generation (F1) PDX tumor material was interrogated. Differential expression analysis was carried out on all samples with comparisons of normal, tumor and F1 generation. Across all comparisons there were approximately 4000 genes and miRNAs found to be differential expressed. In focusing on genes that were upregulated in tumor samples compared to normal and further upregulated in the PDX F1 samples compared to the tumor samples, we identified 88 genes of interest. Biological processes such as cell division, mitotic cell cycle processes and cell cycle processes characterized a significant number of these genes. Two of the key genes of interest in this analysis were TSPAN1 and TPX2. TSPAN1 was upregulated 9.5-fold in tumor-normal comparison and upregulated a further 2.3-fold in the PDX F1 compared to the patient tumor. TPX2 was upregulated 4.4-fold in the tumor-normal comparison and a further 3.9-fold increase in the PDX tumor compared to patient tumor. TSPAN1 has previously been shown to increase the metastatic and invasive potential of pancreatic ductal adenocarcinoma cell lines. TPX2, a microtubule-associated protein, has been shown to reduce tumor growth in vivo when silenced. The pancreatic PDX biobank represents a versatile, expandable patient cohort for preclinical investigation. Analysis of gene expression profiles of normal vs tumor and tumor Vs PDX showed genes with associated tumor proliferation and aggressiveness. Citation Format: Sandra Roche, Fiona O'Neill, Niall Swan, Ninfa L. Straubinger, Neil T. Conlon, Jean Murphy, Kevin Conlon, Ray McDermott, Justine Meiller, Justin Geoghegan, Michael Moriarty, Robert M. Straubinger, Martin Clynes. Establishment and characterization by expression microarrays of a patient-derived xenograft biobank for human pancreatic adenocarcinoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 1678.

Editorial introductions

Editorial introductions

Physiotherapist-Led Triage at a Rheumatology-Based Musculoskeletal Assessment Clinic: an 18-Month Service Evaluation of Activity and Outcomes.

ObjectivePhysiotherapist‐led musculoskeletal triage clinics are an effective and efficient means of managing patients presenting with musculoskeletal disorders in primary and secondary care. Data regarding the activity and outcomes of physiotherapist‐led triage in hospital‐based outpatient rheumatology clinics are scarce. Thus, the aim of this study was to undertake a service evaluation of activity and outcomes of a physiotherapist‐led rheumatology‐based Musculoskeletal Assessment Clinic (MAC). The primary objective was to quantify the proportion of patients independently managed by the clinical specialist physiotherapists (CSPs).MethodsA retrospective service evaluation was undertaken of all patients who attended the Rheumatology MAC at St Vincent's University Hospital, Dublin (SVUH) between August 2012 and February 2014. The Clinical Audit Department of SVUH approved the study. Data were analyzed using descriptive statistics.ResultsFive hundred and eight patients attended the MAC: 76% were female and the mean age was 55 years and ranged between 18‐91. Seventy‐five percent of patients were independently managed by the CSP without needing to see a consultant rheumatologist, whereas 17% were referred to the rheumatology team. Eighty‐seven percent of patients referred to the rheumatology team had rheumatological intervention (eg, injection, medical management, or multidisciplinary rehabilitation). A substantially higher proportion of patients with regional musculoskeletal pain and degenerative conditions were independently managed by the CSP compared with those who had rheumatological/inflammatory conditions.ConclusionThe majority of patients who attended the MAC were independently managed by the physiotherapists, suggesting that physiotherapist‐led triage may be a useful and efficient means of managing a proportion of patients referred for a specialist rheumatological consultation.

Apnea Recognition with Wavelet Neural Networks

Apnea is a Sleep Disorder Syndrome characterized by an interruption or reduction of air flow for at least 10 seconds. Polysomnography is a test used to apnea diagnosis. Several signals, including Electrocardiogram (ECG), Electroencephalogram (EEG) and Oxygen Saturation (SpO_2) are obtained in this diagnostic test. Since most tests for apnea are uncomfortable, there is an increase search for alternative methods to reduce cost and improve patient well-being.In this work, we use only SpO_2 data from 25 patients of the St Vincent's University Hospital, Dublin, to extract parameters connected to a Neural Network attempting to classify patients with apnea or non-apnea. Results confirm that our alternative method can be used as an auxiliary tool for diagnosis by using exclusively SpO_2 signal.