Senior Data Engineer DraftKings IncSenior Data EngineerBoston, MAA Bachelor's Degree in Computer Science or a related field, or an equivalent combination of education, training, and professional experience, with at least 3 years of experience designing, building, and maintaining scalable data platforms and distributed data systems. Leverage AI throughout the software development lifecycle to improve engineering productivity, enhance data quality, and build trusted data products that enable AI-powered applications and natural language access to data.
Distinguished Cyber Software Engineer The Charles Stark Draper Laboratory IncDistinguished Cyber Software EngineerCambridge, MA$100,000–$275,000 / yearDraper supports many programs to improve work-life balance including workplace flexibility, employee clubs ranging from photography to yoga, health and finance workshops, off site social events and discounts to local museums and cultural activities. Works independently, in conjunction with defensive software or hardware cybersecurity professionals for red team efforts, or with other cross-domain professionals for targets that intersect other technical areas.
Distinguished Systems Engineer for Embedded Microsystems Architecture and Design The Charles Stark Draper LaboratoryDistinguished Systems Engineer for Embedded Microsystems Architecture and DesignCambridge, MassachusettsThe Embedded Microsystems and Sensors Group at Draper is seeking a Principal Systems Engineer to develop and manage requirements, architecture, interface documentation, and system specifications for systems in mission domains such as: embedded secure communications, advanced electronics miniaturization, edge processing and computing, trustworthy secure platforms, and autonomous air/sea vehicles. Technical depth in fields relevant to electronics development, embedded systems, embedded software, or packaging miniaturization such as: Possess a broad understanding of microprocessors, Field Programmable Gate Arrays (FPGAs), Application Specific Integrated Circuits (ASICs), and real-time software & firmware needed to enable solutions.
Deployment & Applications Engineer Wonder GroupDeployment & Applications EngineerBoston, MassachusettsAs we expand our footprint of Infinite Kitchens, we are seeking a Robotics Deployment & Applications Engineer to support the deployment of our Infinite Kitchens across the country and development of customer solutions in the lab. Work closely with Hardware/Software Engineers in the lab supporting new projects, tests and product development (happens between deployments).
Product Quality Assurance Engineer ZOLL MedicalProduct Quality Assurance EngineerChelmsford, MassachusettsRemoteThis role partners with Engineering, Manufacturing, Regulatory, and Post-Market teams to support investigations, analyze product performance, and contribute to activities that improve product reliability, patient safety, and compliance for medical devices. The Acute Care Technology division of ZOLL Medical Corporation develops and delivers innovative lifesaving products and software solutions to EMS, hospital, public safety, and military customers globally.
Engineer 1 TPG Hotels & ResortsEngineer 1Dedham, MassachusettsPhysical requirements include extended standing and walking, climbing, bending, reaching, pulling, pushing, kneeling, and lifting to 50lbs -- 100lbs. Respond promptly to emergency situations, such as power outages, water leaks, and fire alarms, and take appropriate actions to ensure guest and staff safety.
NewPrincipal RF Communications Engineer The Charles Stark Draper LaboratoryPrincipal RF Communications EngineerCambridge, MassachusettsDraper supports many programs to improve work-life balance including workplace flexibility, employee clubs ranging from photography to yoga, health and finance workshops, off site social events and discounts to local museums and cultural activities. The role requires excellent communication skills and the ability to effectively collaborate with multidisciplinary groups, including software, hardware, and material engineering.
NewSenior Product Quality Engineer ANDURIL INDUSTRIESSenior Product Quality EngineerLexington, MA$146,000–$194,000 / yearWorking knowledge of Quality core tools such as Failure Modes and Effects Analysis (FMEA), Root Cause and Corrective Action (RCCA/8D), Change Management, Advanced Product Quality Planning (APQP), Production Part Approval Process (PPAP) and Geometric Dimensioning and Tolerancing (GD&T). Work cross-functionally to define and execute the product roadmap, partnering with production to ensure incoming material inspection, process control plans and end of line tests capture the essential quality requirements for successful customer shipments.
NewSenior Manufacturing Quality Engineer ANDURIL INDUSTRIESSenior Manufacturing Quality EngineerLexington, MA$146,000–$194,000 / yearWorking knowledge of Quality core tools such as Failure Modes and Effects Analysis (FMEA), Root Cause and Corrective Action (RCCA/8D), Change Management, Advanced Product Quality Planning (APQP), Production Part Approval Process (PPAP) and Geometric Dimensioning and Tolerancing (GD&T). Work cross-functionally to define and execute the product roadmap, partnering with production to ensure incoming material inspection, process control plans and end of line tests capture the essential quality requirements for successful customer shipments.
Senior Sustaining Engineer - Electromechanical Systems SIG SAUER IncSenior Sustaining Engineer - Electromechanical SystemsNHToday, SIG SAUER is synonymous with industry-leading quality and innovation which has made it the brand of choice amongst the U.S. Military, the global defense community, law enforcement, competitive shooters, hunters, and responsible citizens. Your responsibilities include troubleshooting and resolving complex production issues on a short time frame, implementing design enhancements, and coordinating changes with Quality Assurance, Operations, and R&D teams.
Senior Energy Engineer (Hybrid Schedule) Eversource EnergySenior Energy Engineer (Hybrid Schedule)MA$115,730–$128,590 / yearTo learn about our progress in important areas including technology innovations, our growing renewable energy portfolio, the environmental considerations of our operations, and how we personally contribute to the vitality of our communities and grow our business in a responsible manner, please read our Eversource Sustainability Report. Responsible for review and approval of complex projects/programs, which require an understanding of extensive engineering analysis/calculations, implementation strategy for new technologies, or energy simulation modeling.
Senior Software Engineer - Data Acquisition Team Zoominfo Technologies IncSenior Software Engineer - Data Acquisition TeamWaltham, MA$140,000–$220,000 / yearAbout us: ZoomInfo (NASDAQ: GTM) is the Go-To-Market Intelligence Platform that empowers businesses to grow faster with AI-ready insights, trusted data, and advanced automation. ZoomInfo - Data Acquisition Page 1- Experience designing ETL/ELT workflows that process large volumes of structured and semi-structured data.
Embedded Software Engineer Illinois Tool Works IncEmbedded Software EngineerMA$78,400–$130,000 / yearJob Description: Objective of role: The Embedded Software Engineer is responsible for the design, development, testing, and support of embedded software solutions for both existing and new products, including new hardware bring-up, low-level hardware/software integration, and support of microcontroller-based embedded systems. The ideal candidate is comfortable working close to the hardware and can efficiently diagnose and resolve low-level issues involving microcontrollers, memory, interfaces, sensors, and communication devices.
Pre-sales Solutions Engineer (AV/IT) - Boston, MA ShurePre-sales Solutions Engineer (AV/IT) - Boston, MABoston, MassachusettsRemote$59,400–$96,800 / yearFull timeOur benefits include comprehensive healthcare, mental health and retirement savings plans, generous paid time off programs, employee discounts, professional development opportunities, work-life balance initiatives, employee recognition programs, and volunteering/community involvement opportunities. Team Collaboration: Work closely with the sales team, marketing department, customer success, and technical experts to ensure cohesive and comprehensive customer experiences.
Senior Ai/Ml Engineer, Physical AI Solutions (UR & Mir, North Reading, MA) Teradyne, Inc.Senior Ai/Ml Engineer, Physical AI Solutions (UR & Mir, North Reading, MA)North Reading, MA$219,800–$351,700 / yearAs a senior member of the team, you'll collaborate closely with R&D teams at Universal Robots and Mobile Industrial Robots, helping shape the future of collaborative robotics and autonomous mobile platforms across the Teradyne Robotics portfolio. Working across our platform for simulation and data generation, you'll help engineer solutions that leverage diverse sensor modalities-from RGBD cameras and LiDAR to Time-of-Flight sensors-making informed trade-offs based on performance, cost, and application requirements.
Twin-Ax Cable Product Engineer Amphenol TCSTwin-Ax Cable Product EngineerNashua, New HampshireAmphenol Corporation is one of the world’s largest designers and manufacturers of electrical, electronic and fiber optic connectors and interconnect systems, antennas, sensors and sensor-based products and coaxial and high-speed specialty cable. The Twin-Ax Cable Product Engineer is the technical owner for high-speed copper cable assemblies, responsible for ensuring mechanical reliability, electrical performance, manufacturability, and long-term product integrity.
Staff/Principal Full Stack Software Engineer AxonStaff/Principal Full Stack Software EngineerBoston, MA$168,750–$270,000 / yearOur product's north star is to make an impact on the world by reducing the amount of time officers spend at their desks writing reports and increase the amount of time officers spend out in their communities helping the public. The actual base pay is dependent upon many factors, such as: level, function, training, transferable skills, work experience, business needs, geographic market, and often a combination of all these factors.
Electrical Engineer Merlin LabsElectrical EngineerBoston, MAProvide guidance to other electrical engineers and technicians across the team working on electrical and electronic aspects of the system architecture and schematics including power, computer, electro-mechanical, interconnect systems, wireless communications, cable harnesses, packaging, cable routing, and user interfaces and controls. If you require reasonable accommodation in completing an application, interviewing, completing any pre-employment testing, or otherwise participating in the employee selection process, please direct your inquiries to: people@merlinlabs.com
NewLaser Test Engineer ANDURIL INDUSTRIESLaser Test EngineerLexington, MA$98,000–$130,000 / yearThis third-party service provider provides risk-intelligence services that may include analysis of sanctions and watchlists, adverse media, public-record information, and other lawful open-source or commercial data sources. To ensure your safety and help you navigate your job search with confidence, please keep the following critical points in mind: No Financial Requests: Anduril will never solicit payment or demand personal financial details (such as banking information, credit card numbers, or social security numbers) at any stage of our hiring process.
NewCamera Test Engineer ANDURIL INDUSTRIESCamera Test EngineerLexington, MA$98,000–$130,000 / yearThis third-party service provider provides risk-intelligence services that may include analysis of sanctions and watchlists, adverse media, public-record information, and other lawful open-source or commercial data sources. To ensure your safety and help you navigate your job search with confidence, please keep the following critical points in mind: No Financial Requests: Anduril will never solicit payment or demand personal financial details (such as banking information, credit card numbers, or social security numbers) at any stage of our hiring process.
Lead SCADA Engineer National Grid PlcLead SCADA EngineerMA$142,000–$166,000 / yearResponsible for the design, configuration, installation oversight, and support of repair and maintenance for all monitoring and control equipment including, electronic sensing devices, flow computers, Remote Terminal Units (RTUs), Programmable Logic Controllers (PLCs), data communications equipment and services, computer hardware, and other gas telemetry devices. Coordinate with operating and maintenance personnel to provide for proper calibration, repair and maintenance of gas measurement and telemetry equipment at custody transfer points, and large volume customers to ensure the accuracy of field equipment.
Senior QA SW Engineer - Salem, NH(10302) Extreme Networks IncSenior QA SW Engineer - Salem, NH(10302)Salem, NH$120,000–$140,000 / yearRequired Skills & Experience: Hands-on experience in wired networking protocols including VLAN, IP, STP, TCP/UDP, VRRP, OSPF, BGP, MPLS, IS-IS, SPBM. Strong knowledge of network infrastructure services including DHCP, DNS, RADIUS, LDAP, SSH, and Certificate Authorities.
Security Engineer QuEra Computing IncSecurity EngineerBoston, MA$90,000–$140,000 / yearAs a Security Engineer, you will be part of our growing IT, Security & Compliance team, designing, administrating and configuring security baselines/best practices for on-premises and cloud environments, assisting teams with vulnerability management, gathering evidence for audits, and more. Strong, professional communication skills, both verbal and written, including the skill in articulating and translating technical language to non-technical customers.
Site Reliability Engineer Qlik Technologies IncSite Reliability EngineerBoston, MARemoteHere's how you'll be making an impact: Reliability and Scalability: Ensure high reliability and availability of our cloud platforms, collaborating with cross-functional teams to implement new infrastructure features and optimize performance. We excel in integration and governance solutions that work with diverse data sources, and our real-time analytics uncover hidden patterns, empowering teams to address complex challenges and seize new opportunities.
Senior Product Software Engineer, Cloud & AI (.Net/Azure) Wolters KluwerSenior Product Software Engineer, Cloud & AI (.Net/Azure)Waltham, MA$92,700–$161,850 / yearWe've been recognized by employees as a European Diversity Leader in the Financial Times, as one of Forbes America's Best Employers for Diversity in 2022, 2021 and 2020 and as one of Forbes America's Best Employers for Women in 2021, 2020, 2019 and 2018. Wolters Kluwer, Finance and Corporate Compliance division, ComplianceOne is a highly configurable document generation solution and loan processing system that provides you with access to a wide range of features.
Principal Data Engineer (Service) Waters CorpPrincipal Data Engineer (Service)Milford, MAYou will bring deep technical expertise in service business data domains, operate with a high degree of independence, and contribute to the design and delivery of scalable data platforms that enable strategic decision-making for revenue growth, margin expansion, and operational excellence initiatives targeting $200M+ in EBIT improvement. Design and build scalable, reliable data platforms that integrate service delivery data (work orders, cases, products, geography), service team member data (roles, locations, workloads), service revenue and cost data, and proforma P&L information to enable strategic decision-making.
Quality Engineer BAE Systems PlcQuality EngineerNashua, NH$97,008–$164,914 / yearAbout BAE Systems Electronic Systems BAE Systems, Inc. is the U.S. subsidiary of BAE Systems plc, an international defense, aerospace and security company which delivers a full range of products and services for air, land and naval forces, as well as advanced electronics, security, information technology solutions and customer support services. At our core are more than 14,000 highly talented Electronic Systems employees with the brightest minds in the industry, we make an impact - for our customers and the communities we serve.
Data Engineer, Data Platform - Distribution KKR & Co IncData Engineer, Data Platform - DistributionBoston, MA$180,000–$210,000 / yearThis is a pivotal, hands-on technical leadership role with ownership of the end-to-end architecture across modern web applications, API and service layers, cloud data platforms, identity and access controls, AI-enabled user experiences, and business intelligence integrations. Translate product and operational priorities into scalable technical designs across Data Explorer's core capability areas: report consolidation, persona-based landing experiences, Sigma integration, AI and Data Rooms, external client access, and administrative and user-support capabilities.
Lead Software Platform Engineer TetraScienceLead Software Platform EngineerBoston, MAThis is a highly impactful seat for an engineer who has built authorization and governance systems as products (not just consumed them), understands the trade-offs of large-scale distributed design, and thrives on turning ambitious scalability goals into concrete technical strategy. We are catalyzing the Scientific AI revolution by designing and industrializing AI-native scientific data sets, which we bring to life in a growing suite of next gen lab data management solutions, scientific use cases, and AI-enabled outcomes.
Electrical Engineer Globus Medical, Inc.Electrical EngineerMethuen, MAYou will work closely with a dynamic team of electrical, software, and mechanical engineers to conceptualize and commercialize innovative medical devices to meaningfully impact the lives of patients with musculoskeletal disorders. + Consider market feedback from surgeons and other customers to determine functional and design specifications for new product development and continuous improvements.
Staff Software Engineer, Undersea Reconnaissance and Strike Anduril Industries IncStaff Software Engineer, Undersea Reconnaissance and StrikeBoston, MA$220,000–$292,000 / yearTo ensure your safety and help you navigate your job search with confidence, please keep the following critical points in mind: No Financial Requests: Anduril will never solicit payment or demand personal financial details (such as banking information, credit card numbers, or social security numbers) at any stage of our hiring process. Collaborating closely with program leadership and cross-functional teams from other Anduril products, you'll ensure that designs align with customer requirements while maintaining traceability to program office technical decisions.
Engineer, Power Plant Control (SCADA) Power FactorsEngineer, Power Plant Control (SCADA)Boston, MassachusettsTypical implementation-activities involve interacting with our customers and possibly with the grid operators to gather all information needed, perform the requirements analysis, provide the design study and finally complete the grid integration/compliance tests and submit the respective report. As a part of the Controls & Grid Integration team, your mission is to deliver grid integration and power plant control related engineering tasks for solar, storage and hybrid sites during the projects execution phase.
Engineer, Power Plant Control (Scada) Power FactorsEngineer, Power Plant Control (Scada)Boston, MATypical implementation-activities involve interacting with our customers and possibly with the grid operators to gather all information needed, perform the requirements analysis, provide the design study and finally complete the grid integration/compliance tests and submit the respective report. As a part of the Controls & Grid Integration team, your mission is to deliver grid integration and power plant control related engineering tasks for solar, storage and hybrid sites during the projects execution phase.
Full Stack Software Engineer ManulifeFull Stack Software EngineerBoston, MA$90,160–$128,800 / yearManulife offers eligible employees a wide array of customizable benefits, including health, dental, mental health, vision, short- and long-term disability, life and AD&D insurance coverage, adoption/surrogacy and wellness benefits, and employee/family assistance plans. Position Responsibilities: Develop and maintain clean, well-documented, and efficient code for both the front-end (React, HTML, CSS, JavaScript) and back-end (your preferred server-side language, .NET/C#).
Software Engineer III - PA085 Zoominfo Technologies IncSoftware Engineer III - PA085Waltham, MA$112,000–$176,000 / yearDevelop ETL/ELT workflows and processing jobs using technologies such as Apache Airflow, Apache Beam, Google Dataflow, DataProc, Spark, Kafka, or Pub/Sub. You will be joining a team that works on large-scale data infrastructure, high-impact product capabilities, and engineering problems where reliability, scale, and data.
Staff Functional QA Engineer Symbotic IncStaff Functional QA EngineerWilmington, MA$125,000–$171,600 / yearIn this role, "embedded" means working directly with the software engineering teams that tie together real-time orchestration, robotics, on-prem and edge components, and customer-facing experiences-end-to-end behavior where hardware, services, and timing meet. Applying next-gen technology, high-density storage and machine learning to solve today's complex distribution challenges, Symbotic enables companies to move goods with unmatched speed, agility, accuracy and efficiency.
Manufacturing Test Engineer I Axcelis TechnologiesManufacturing Test Engineer IBeverly, MassachusettsThis position provides exposure to a wide range of engineering disciplines, including electronics, mechanical design, automation, instrumentation, data analysis, and troubleshooting of complex test systems. This is an exciting opportunity for an early‑career engineer to gain hands‑on experience, work with cross‑functional technical teams, and develop practical engineering skills that drive real-world impact.
NewMechanical Engineer - Undersea Reconnaissance & Strike ANDURIL INDUSTRIESMechanical Engineer - Undersea Reconnaissance & StrikeQuincy, MA$129,000–$171,000 / yearThis role involves close collaboration with vehicle design engineering, field operations, and manufacturing/maintenance teams as well as customer representatives to ensure effective support and execution of missions in a variety of rugged environments. Anduril's Maritime Division has assembled a diverse team of experts in software, robotics, artificial intelligence, sensor fusion, and data analysis to create software and hardware solutions that radically evolve the capabilities of our customers.
Senior Software Engineer, Robotics Data Foundation (Cloud) ANDURIL INDUSTRIESSenior Software Engineer, Robotics Data Foundation (Cloud)Boston, MA$220,000–$292,000 / yearBuild and develop cloud-native systems that are also edge-compatible: While we are responsible for delivering an excellent cloud data platform experience for all teams across Anduril, we also deliver a subset of capabilities to edge nodes to facilitate telemetry capture in offline / air-gapped settings. Our vehicle telemetry platform powers software and hardware development, T&E workflows, production incident response, and contractual customer reporting today, and underpins new product development, fleet-wide analysis, simulation, and machine learning workflows.
Senior Electrical Engineer, Maritime ANDURIL INDUSTRIESSenior Electrical Engineer, MaritimeQuincy, MA$146,000–$194,000 / yearIf you are passionate about solving problems that have real impact and working on systems that directly contribute to achieving national strategic priorities, we want you to join Anduril's Maritime Division and help us build the future of defense capability. Anduril's Maritime Division has assembled a diverse team of experts in software, robotics, artificial intelligence, sensor fusion, and data analysis to create software and hardware solutions that radically evolve the capabilities of our customers.
Software Engineer, Robotics Data Foundation (Cloud) ANDURIL INDUSTRIESSoftware Engineer, Robotics Data Foundation (Cloud)Boston, MA$191,000–$253,000 / yearBuild and develop cloud-native systems that are also edge-compatible: While we are responsible for delivering an excellent cloud data platform experience for all teams across Anduril, we also deliver a subset of capabilities to edge nodes to facilitate telemetry capture in offline / air-gapped settings. Our vehicle telemetry platform powers software and hardware development, T&E workflows, production incident response, and contractual customer reporting today, and underpins new product development, fleet-wide analysis, simulation, and machine learning workflows.
Electrical Engineer - Maritime ANDURIL INDUSTRIESElectrical Engineer - MaritimeQuincy, MA$129,000–$171,000 / yearIf you are passionate about solving problems that have real impact and working on systems that directly contribute to achieving national strategic priorities, we want you to join Anduril's Maritime Division and help us build the future of defense capability. Anduril's Maritime Division has assembled a diverse team of experts in software, robotics, artificial intelligence, sensor fusion, and data analysis to create software and hardware solutions that radically evolve the capabilities of our customers.
Senior Quantum Success Engineer Qblox NVSenior Quantum Success EngineerBoston, MAOur Quantum Success Engineering (QSE) team plays a pivotal role in ensuring our customer's success by providing proactive technical support, gathering feedback, and ensuring customers derive ongoing value from the products. Identifying, understanding and leading the key success drivers for customers researching superconducting or spin qubits, and leading customer success initiatives in collaboration with application scientists and the R&D department.
Full-Stack Software Engineer Manulife Financial CorpFull-Stack Software EngineerBoston, MA$90,160–$167,440 / yearYou'll collaborate with global development teams and business stakeholders to turn actuarial and mathematical models into user-friendly, performant applications that impact millions of customers and help redefine how we deliver insurance solutions. Manulife offers eligible employees a wide array of customizable benefits, including health, dental, mental health, vision, short- and long-term disability, life and AD&D insurance coverage, adoption/surrogacy and wellness benefits, and employee/family assistance plans.
Geotechnical R&D Engineer Viridien SAGeotechnical R&D EngineerActon, MA$90,000–$100,000 / yearIn this role, you will be a key contributor to our Production, Research, and Development (R&D) division, collaborating with engineers, clients, and industry partners to enhance existing products and develop next-generation testing systems. With over 40 years of experience, Geocomp is well-positioned to help clients on a wide range of projects, providing geostructural consulting, monitoring, and laboratory testing services worldwide.
AI Ssytems Engineer Phaxis LLCAI Ssytems EngineerBoston, MAIt combines deep technical engineering capability with applied artificial intelligence, focusing on the responsible deployment and maintenance of commercial large language models (LLMs), ChatGPT Enterprise, Claude Chat and Cowork, Microsoft Copilot, Power Platform, and workflow automation technologies. 6+ years of experience integrating systems using REST APIs, SDKs, and SQL, and experience designing, deploying, or supporting Model Context Protocol (MCP) servers or comparable middleware architectures that enable secure, governed AI access to enterprise data sources.
Senior Machine Learning Engineer DraftKings IncSenior Machine Learning EngineerBoston, MAAs a Senior Machine Learning Engineer, you'll design, implement, and scale production-grade data and machine learning pipelines that drive measurable business outcomes. The Fintech Data Science team builds and maintains systems that protect DraftKings and its customers from fraud, payment risk, and abuse.
Machine Learning Engineer Quantum MachinesMachine Learning EngineerCambridge, MAIn this role, you will work at the intersection of machine learning, quantum physics, and software engineering, translating noisy, non-stationary, safety-critical control problems into ML solutions that run on real hardware in production labs. This position offers unprecedented exposure to diverse qubit types and quantum architectures, with a tight feedback loop between your models and the systems they steer, and the opportunity to deliver groundbreaking ML-driven solutions to the labs and companies defining the next generation of quantum systems.
Software Engineer 3 Hewlett Packard Enterprise CoSoftware Engineer 3Westford, MA$120,500–$228,500 / yearYou will collaborate closely with Software Development, Test Engineering, and Product teams to design comprehensive test strategies, develop automation frameworks, validate new features, and ensure high-quality software releases. Please note that Hewlett Packard Enterprise (HPE), its direct and indirect subsidiaries and affiliated companies, and its authorized recruitment agencies/vendors will never charge a candidate a registration fee, hiring fee, or any other fee in connection with its recruitment and hiring process.
Principal Pricing Data Engineer Waters CorpPrincipal Pricing Data EngineerMilford, MAStrong business domain knowledge and experience working with enterprise systems such as SAP (e.g., supply chain data, orders, revenue recognition, pricing), Salesforce (commercial operations), and/or Service Excellence domains, with the ability to translate business processes into scalable data solutions. We collaborate with customers around the world to advance the release of effective, high-quality medicines, ensure the safety of food and water, and drive better patient outcomes by detecting diseases earlier, managing routine infections, and combating antibiotic resistance.