Ask HN: Who is hiring? (February 2017)

690 points by whoishiring ↗ HN
Please lead with the location of the position and include the keywords REMOTE, INTERNS and/or VISA when the corresponding sort of candidate is welcome. When remote work is not an option, please include ONSITE. A one-sentence summary of your interview process would also be helpful.

Submitters: please only post if you personally are part of the hiring company—no recruiting firms or job boards.

Readers: please only email submitters if you personally are interested in the job—no recruiters or sales calls.

You can also use kristopolous' console script to search the thread: https://news.ycombinator.com/item?id=10313519.

1,300 comments

[ 2.8 ms ] story [ 589 ms ] thread
Gambit Research Ltd (http://gambitresearch.com) | London, UK | ONSITE | Full time

At Gambit we research and manage automated sports betting algorithms on behalf of our clients. Their algorithms run on our proprietary execution platform which interfaces with a large variety of bookmakers and exchanges, enabling access to the best prices and massive liquidity.

Our distributed, concurrent system has a core written in Erlang, which interacts with a wide variety of Python processes across the rest of the business. Some of the other technologies we use are: Linux (Ubuntu, CentOS), Docker, Kubernetes, Ansible, C, C++, Julia, R, Go, JavaScript, AngularJS, ReactJS, Django, PostgreSQL, Redis, Apache Spark, Apache Kafka, RabbitMQ, Celery, Elasticsearch, Logstash, Kibana, Graphite, Sentry, Git, GitLab.

We have a very flat hierarchy and an emphasis on employee freedom. We encourage our team to work on projects that interest them, as we believe people are happiest and most productive when intellectually stimulated. You don't need to be interested in sports or betting.

We're actively hiring for the following positions:

  - Software developer
 
More information can be found at http://gambitresearch.com/jobs.html
I know how to solve the application challenge, i've just been putting it off since December!
Oden Technologies | https://oden.io | New York, NY | Full-time | Onsite

We are an IoT startup creating a hardware / software platform for Industry 4.0 factories [1]. We collect data from industrial machinery and analyze, aggregate and display it so that manufacturers can make more product with less material. There's a lot of exciting things happening at the company and now is a great time to get into a small (8-person) team working working on a lofty mission that will revolutionize an underserved industry.

* Data Engineer: responsible for building and maintaining scalable APIs, the secure and timely ingestion of millions of time-series data points daily, building realtime and batch data pipelines and integrating models created by our data scientists into our product in order to generate realtime insights and predictions about production processes.

* Frontend Engineer: We need a solid front-end / JavaScript engineer with React experience, to help us design, build, and deploy the next-generation factory analytics platform.

* Forward Deployed Engineer: You'd be responsible for deploying, installing, monitoring and improving our on-premise devices, as well as building out the code that runs on them. Much of the code is communicating at low level (ex: Modbus) with industrial machinery and reporting back to our analytics platform.

Read more on https://oden.io/joinus or feel free to reach out to us directly: hello@oden.io

[1] http://www.mckinsey.com/business-functions/digital-mckinsey/...

MORSE Corp | Software engineer | Boston, Cambridge | ONSITE | www.morse-corp.com/jobs

MORSE is an employee owned company based in the technical hub of Kendall Square, Cambridge MA. We develop algorithms and software for operational systems, implementing leading edge technologies for robotics, autonomous air and undersea vehicles, and coordination of human teams.

We are hiring for several positions, including:

Full Stack Web Developer

Robotics Software Engineer

Vision Navigation & Estimation Engineer

Machine Learning & AI Engineer

Senior Software Architect

Visit us at http://morse-corp.com/jobs to learn more and apply.

Aclaimant, Inc | Software Engineer, Clojure | US | Full-time, REMOTE, aclaimant.com

Aclaimant is looking to expand it's development team. We're a small team that is looking to grow significantly this year. We work remotely from the comfort of our own homes. Our current stack consists of Clojure for our servers and ClojureScript on our front end. If you're interested in learning more, contact us at jobs@aclaimant.com

DTU Biosustain | Software Engineer (Web) | Copenhagen, Denmark | Full-time, ONSITE, VISA, http://biosustain.dtu.dk

We are seeking a developer to join our team developing a web platform that supports genetic engineering of microbial strains for sustainable chemical production at our center. We write services and UIs for storage, analysis and visualization of experimental data produced by our scientists.

Our stack in no particular order: JavaScript, TypeScript, Angular, Angular-Material, Python, Flask/aiohttp/gRPC, Redis, PostgreSQL, NumPy/SciPy, Biopython, Docker

You would be expected to have strengths in developing single-page web applications, development using Python or both. A collaborative attitude, interest in science and willingness to learn matters more than knowing specific tools.

To read more about the position and apply, visit:

http://stackoverflow.com/jobs/132915/developer-for-scientifi...

You are also welcome to email me directly at lays@biosustain.dtu.dk

Hologram | Chicago, IL | Full-time | http://boards.greenhouse.io/hologram

Our mission is to build the platform for creating connected products by tackling some of the hardest challenges at the intersections of hardware, connectivity, and software.

At Hologram, we believe in you and your immediate squad members to know what's best for our platform and enable you to make immediate customer-impacting decisions. You can see this in how we develop products and processes: Hologram pushes decision-making out to the edges of the organization to reduce management overhead and increase speed to market.

We have a number of open positions and would love to hear from you!

+ Embedded Systems Engineer: http://boards.greenhouse.io/hologram/jobs/561434 *Remote Available

+ Full Stack Cloud Engineer: http://boards.greenhouse.io/hologram/jobs/562395

+ Full Stack Engineer: http://boards.greenhouse.io/hologram/jobs/562369

+ Customer Success Engineer: http://boards.greenhouse.io/hologram/jobs/541597

+ Product Designer: http://boards.greenhouse.io/hologram/jobs/580826

For any questions, feel free to email me directly at derrick@hologram.io

Nava | Washington DC & San Francisco SF | DevOps/Infrastructure/Systems Engineers, Software/Fullstack Engineers | Product and Project Managers | On-site - Full-time | $100k-$160k+ + equity + benefits

We're a small team of engineers, designers, and product builders that were brought in to help fix Healthcare.gov in the winter of 2013. Our revamped application is used by millions, converts 35% better, and halves the completion time.

It turns out there’s a lot more to reimagine within government services, which is why we’re partnering with both the Department of Veterans Affairs and Medicare. With the VA, we are working to modernize their appeals system, making millions of veteran’s lives better through the process. Today, the average appeal takes 5 years to process; we can fix this. For Medicare, we are designing and building the architecture for Medicare's historic transition towards value-based care.

It’s surprising how much can be done by a small group of empathetic people with a Silicon Valley mindset, deep technical experience, working closely with dedicated civil servants in government. We’ve started Nava as a public benefit corporation to radically improve how our government serves its people, and we believe that the services our government provides should be clear and reliable. If you feel the same way, we'd love to hear from you at jobs@navahq.com

Learn more about working here: http://navahq.com/careers

Job descriptions: http://jobs.lever.co/nava

Our blog: https://blog.navapbc.com/

Amazon | Edinburgh, UK | Full Stack Engineers - On-site Only | Relocation Assistance Available | Full Time | Visa Sponsorship available

Amazon development Centre (Scotland) is looking for experienced software developers with strong technical ability, a focus on the customer experience, great teamwork and communication skills, and a motivation to achieve results in a fast-paced environment.

Our development centre in Edinburgh is responsible for devising and growing innovations for Amazon around the world. Small teams of developers, designers and leaders run major parts of Amazon’s business, technology and operations. From interactive UI design to large-scale distributed systems and machine learning, we do whatever it takes to deliver great products and experiences for our customers.

Our work is characterised by high scale, complexity and the need for invention. We offer great opportunities to work on big data, machine learning and high-scale, low-latency distributed systems. We use a wide variety of languages including Java, Python, Ruby, and JavaScript; Open Source technologies including Linux, Ruby on Rails, and AngularJS; and we build on top of Amazon’s world-leading AWS platform.

For more information take a look at our microsite - http://www.amazondc.com

Feel free to get in touch with me – contact details in my profile - if you are interested in having an informal chat about roles here.

(Please note, I only recruit for the Edinburgh Dev Centre, so cannot help you with other roles/locations)

Solworks | Full-stack Developer Node.js | Leicester UK, Nottingham UK | ONSITE | Full time

We: Are a small startup creating beautiful SaaS applications to help companies manage employee time and holiday in a simple and consistent manner.

You: Are an enthusiastic developer who loves all things JavaScript, including its quirks, and wants to write modern, clean code. You are able to learn new things but also aren't afraid to teach what you know.

Using:

* React

* Sequelize

* Semantic-UI

* Hapi, Nginx

* Swagger / OpenAPI

* Babel & Gulp & Mocha & ESLint

Bonus Points:

You can spin your own VMs or Containers, you know all your IDE shortcuts, you have existing open-source contributions.

Benefits:

* Exciting challenges.

* Free pizza Friday every month.

* Staff social events including coastal sailing and barbeques.

* Working with passionate, like-minded people.

* Great tea and coffee.

* Relaxed atmosphere and great facilities including our new table football

* As many monitors as you want!

* On-site parking.

If this sounds like your sort of opportunity, drop us a line at hello@sol.works

Dispatch | http://dispatch.ai/ | San Francisco Bay Area, CA | Full-time, onsite

We are Dispatch (dispatch.ai), a well-funded startup that is creating a platform for local delivery powered by a fleet of autonomous vehicles designed for sidewalks and pedestrian spaces.

We're bringing together a team with deep domain expertise in robotics, autonomous vehicles, and artificial intelligence. If you're interested in joining us for work on this exciting technology and help create the future of autonomous vehicles, we'd love to hear from you.

Roles we are hiring for include:

Software Engineer - Motion Planning and Controls

Software Engineer - Perception

Software Engineer - Mapping and Localization

Software - Generalist

Hardware - Electrical

Hardware - Embedded/Firmware

Contact us at jobs-hackernews@dispatch.ai!

Or apply through our listing on AngelList (https://angel.co/dispatch-6/).

Viking Education | Course Mentor | Remote | Part Time | http://www.vikingcodeschool.com

Viking Code School is a 100% online development bootcamp driven by the mission of launching a million high-growth careers around the world regardless of a student’s location, prior experience or economic standing.

Our mentor-led Flex Program pairs students with industry veterans who perform weekly code reviews as part of the learning process. It is a great chance to pass on your knowledge without leaving your day job (or your house). As a mentor, you work with your mentee(s) during their full time in the course, which typically takes between 6-12 months to finish. You meet with your mentee 1-3 times per week for code review and can work with anywhere from 1 to 10+ students, depending on desire and ability.

Our back end has two tracks (Ruby/Rails or Node/Express) and our front end covers JavaScript/React/Redux. As a mentor, you have access to the course materials so you can get up to speed on anything you aren't firm on.

Check-ins are compensated.

Requirements:

* 4+ years of professional development experience as part of an engineering team.

* Strong grounding in CS fundamentals like Data Structures and Algorithms.

* Relevant experience with CS, Ruby/Rails, SQL, JavaScript/React etc.

Email careers@vikingcodeschool.com with your CV, links and anything else that would prove your development or teaching ability and general awesomeness.

IBM Canada | Eclipse OMR Developer | Toronto, ON | Full-time, ONSITE | https://ibm.biz/BdsBQD

The IBM Runtime Technologies team is looking to hire motivated software developers to join our mission to nurture an open source community around the Eclipse OMR toolkit for language

runtimes (https://www.eclipse.org/omr).

We develop the Just-In-Time compiler for various language runtimes (Java, JavaScript, Python, Ruby etc.) built on Eclipse OMR: https://github.com/eclipse/omr. The IBM runtime compiler team

also ports and optimizes industry standard open runtimes such as Google V8 and Node.js. We contribute industry-leading performance and capabilities across multiple hardware platforms

(Intel, ARM, IBM Power and z Systems) and operating systems (Windows, Linux, AIX, z/OS).

We are looking for software developers comfortable in an environment that is predominantly C and C++ based, but also willing to go down to the assembly language level. Polyglot skills are

an asset, as we work in a variety of exhibited scripting languages.

We want to hear from you, please apply here: https://ibm.biz/BdsBQD

As an active developer for the compiler component of the Eclipse OMR project I'm happy to answer any technical questions you may have in relation to this position.
This actually sounds like a perfect position for me. Can you help sponsor visas for Americans? It would help me get through Express Entry.
Unfortunately we cannot. We can only extend an offer to candidates that are eligible to work in Canada.
Interesting. Did IBM laid off HR staff? Even small shops are able to sponsor work permits/visas for Canada...
Ah well. I was probably going to qualify anyway, but it will take a number of months and you'll have filled your position by then.
You might be able to get a work permit through the NAFTA/TN1 process, which is supposed to be pretty painless for you and for the company.
This looks like a very interesting position to me. I currently work at the Linux Technology Center at IBM.

Are you looking only for new hires or would consider internal transfers?

We are looking for motivated candidates :) Please, reach out to me (Dorra Bouchiha) and we can chat some more.
Quividi | Python DevOps | Paris | REMOTE FULLTIME http://www.quividi.com/jobs-python-devops/

Quividi, founded is 2006, has become the world leader in measuring attention in public places, by developing and commercializing a video analytics solution. Using image processing algorithms, our software is able to detect and label faces. The data is then stored and displayed in a back-office hosting billions of anonymous audience events. We are looking for someone to join the Web / Data team. We are a lean and autonomous team, with a lot of freedom in our projects and in the solutions we choose. In the past few years, we have been facing an important growth of the data flux to ingest, store and analyse, both on the infrastructure and software side.

Our technical stack consists of Python / Django / MySQL / Elasticsearch. Experience with Linux administration and these technologies will be appreciated!

Our interview process will start with a phone call, then a more technical interview on-site, and an on machine technical test.

The position comes with extensive medical benefits, competitive compensation and stock options. Send your resume / Github profile / Bitbucket profile / MySpace account at jobs-web@quividi.com

Time to polish my MySpace account. Would you consider mygale.org instead (with a rocketmail email address, of course) ?
Assuming you're in the U.S., you'll need to provide your MySpace credentials at the border when you return from your on-site interview in Paris for this REMOTE position. So yes, do polish it up, and also polish up on your "Strong proficiency in French and English" but be sure not to use the former with the border authorities.
Impressive lulz in this post. Do you require an outrageous sense of humor as well?
I'm not sure if you're replying to me or the company. I have nothing to do with the company, I'm just some random developer wiseguy. I don't see any mention of needing experience with the latest LULZ stack in the posting and I suspect it wouldn't be compatible with ICE. There are worse things than being stuck in Paris with plenty of lulz I would think but YMMV.
Viking Education | JavaScript Instructor | SF or Remote | http://www.vikingcodeschool.com

Viking Code School is a 100% online development bootcamp driven by the mission of launching a million high-growth careers around the world regardless of a student’s location, prior experience or economic standing. Our core program is the only online 12-week Immersive where students only pay tuition when they get a job.

We are looking for an experienced and opinionated full stack web developer who will lead instruction in that program and spearhead the ongoing development of our curriculum. You will work with students and assistant instructors to lead the Immersive Program while architecting changes to the curriculum and supporting materials which are used by all of our programs.

We cycle instructors through our development team (as desired) so you don't have to give up building in order to teach.

Because we are 100% online, this is a REMOTE OK position which allows for a high degree of lifestyle flexibility while giving you a chance to potentially affect millions of lives with the lessons, demos, projects and posts you create. Just note that program hours are based on US time zones.

As the leader of the Immersive Program instruction, you will also be eligible for incentive-based compensation when the students are successful in their job search.

Requirements:

* 5+ years team-based development experience, 3+ in JavaScript and relevant frameworks (e.g. Angular, React...). Strong CS, testing and data fundamentals. Passion for exploring, learning and teaching new and current technologies.

* Significant experience with writing, sharing and educating (e.g. blogging, delivering conference talks, podcasting, teaching, or committing to OSS). Great communication is prized over specific teaching experience.

* Experience running a team

* A legitimate passion for education and, preferably, also a quirky weird sense of fun.

Apply with your CV, a description of why you are a good fit, and any relevant links to Github, conference talks, blog posts etc. to careers@vikingcodeschool.com

Aha! (http://www.aha.io) | Rails & Front End Engineering | REMOTE

Aha! is looking for experienced Ruby on Rails, Javascript and front-end engineers to develop rich interactive experiences in React with a Rails backend. Aha! is the #1 tool for product managers to plan strategy and roadmaps.

Aha! is profitable, you can work from anywhere in North America and we offer excellent benefits.

We use our own product to manage our work (which is especially rewarding), we deploy continuously and we are developing in Rails/CoffeeScript/React/d3. Our entire team is remote - primarily in US and Canada.

http://www.aha.io | email: amy@aha.io

Uken Games | http://uken.com | Toronto | Full time | Onsite

Uken is looking for talented developers to help us build amazing mobile games. In particular, we have positions available for:

Backend Developers

Help us scale our backend to enable a million concurrent players by creating the infrastructure and services (SOA) that underly all of our games. Primary tech is Rails and MySQL, but you'll be working with many more such as Docker, Redis, NSQ, websockets, Hadoop, Spark and InfluxDB.

Software Developers

Join one of our game teams to build something that millions of people will play and love. Primary tech is Unity.

About Uken

We are one of the largest independent game studios in Canada, with hundreds of thousands of players a day across mobile and Facebook.

More info including full job postings at http://uken.com

Powerley | Data Scientist, Android Developer, iOS Developer, NodeJS Engineer | Royal Oak, MI | Full-time | http://www.powerley.com/

Powerley is connecting the smart grid to the smart home and building the next generation of home energy management.

Here are some of the things we do:

- Real-time energy use visualization and personalized feedback

- Energy signal disaggregation to understand of how individual appliances drive aggregate usage in the home

- Home automation and control using key smart home protocols (ZigBee, Z-Wave, Wi-Fi, Bluetooth and Thread)

- Identify problems with appliances before they occur

We're looking for experienced Data Scientists, Android & iOS Developers, and NodeJS Engineers to help us build the platform that provides both the utility and the homeowner a new level of connectivity and intelligence.

If you have any questions feel free to send me a PM or comment. You can apply at http://www.powerley.com/about/careers/

Recent new articles

[1] http://www.businesswire.com/news/home/20170131006068/en/Powe... [2] https://techcrunch.com/video/detroit-hustle-with-tome-powerl... [3] http://www.einnews.com/pr_news/361508874/parks-associates-dt...

PromptWorks | Software Engineer | Philadelphia PA | ONSITE https://promptworks.com/

We are a development shop that focuses on software craftsmanship. Our calling is to help companies create amazing, intuitive web & mobile applications, APIs, products, and services.

Pair programming, continuous integration & delivery, kaizen, and TDD/BDD aren't just ideas we pay lip service to, but core practices of our day-to-day work.

We love polyglots. We use lots of Ruby, Python and JavaScript (mostly React and React-Native), some Elixir and Go.

https://www.promptworks.com/jobs/software-engineer

Distil Networks | SF, DC (Arlington) NC (RDU), London, Stockholm | ONSITE (with a few exceptions) | We block bots on the internet.

Hey y'all - Distil Networks is a growing startup in the web application security industry. We build SaaS that blocks automated threats, like bots and scrapers, from attacking our customer’s websites and APIs. This reduces fraud, content theft, spam, and helps eliminate lots of security issues. We have a global network that actively blocks web traffic based on human/ non-human signatures. Our customers love us, our investors love us, and we’re growing and hiring. We have offices in SF, DC, North Carolina, London, and Sweden! I’m a data scientist / engineer here and still have a great time. Closing in on 3 years for me. I really like all my coworkers (physical and remote) and we have a near-zero jerk count.

What we’re looking for (https://jobs.lever.co/distilnetworks?lever-via=3TYvimYmGi):

Specifically we need:

- Data Engineer (please oh please!) (https://jobs.lever.co/distilnetworks/b81d473f-b69b-4050-a481...)

- Front end engineers (https://jobs.lever.co/distilnetworks/85ecd904-11db-4444-91bf...)

- Engineering Manager (https://jobs.lever.co/distilnetworks/38019be7-7d8a-4d70-83af...)

- Senior full stack devs (https://jobs.lever.co/distilnetworks/b8ee33fb-5a15-400c-a51a...)

- Product manager - Data Vis (https://jobs.lever.co/distilnetworks/d278ca16-8256-449e-a0dd...)

- Support engineer (Arlington) https://jobs.lever.co/distilnetworks/b53c1890-d4e7-4149-bea6...

- Software engineer (https://jobs.lever.co/distilnetworks/c2a5db5c-12ce-40f2-949c...)

Many of these jobs have openings in multiple locations.

We’re also hiring for Marketing, Recruiting, Finance, and Sales! Basically everything.

I keep looking for another data science spot to open up in Raleigh. Wish I could have taken advantage of the openings when your office first opened up but was terrible timing on my end (really enjoyed interviewing though). Also got to meet Tim not too long ago at PyData Carolinas and he's awesome.
Curious Media | Boise, ID | Full Stack Software Engineer | Full-time, onsite

Curious Media is a interactive agency devoted to creating ridiculously fun experiences for children and adults alike. We create everything from kids movie websites to games, apps and connected toys. Our regular clients include Disney, Hasbro, Warner Bros., PBS Kids, Scholastic, Dreamworks and a host of other kid focused companies. http://www.curiousmedia.com

We’ve been around since 2004 and have a team of 35. We are extremely stable and have many employees who have been with the company for 6-12 years now. We are very mindful and focused on being a family friendly workplace, both in the type of jobs we take and our expectations of employees time. We rarely work more than 40 hours a week and when we do, we give PTO at a 1:1 ratio (any hours over 45 in a week).

We are more specifically located in Nampa, about 14 miles west of Boise. Many employees commute from Boise/Meridian and its rarely more than a 25 minute commute as all the traffic is going towards Boise (and the opposite on the way home). This area is amazingly affordable and provides easy access to a wealth of outdoor activities. The closest respectable ski mountain is only about 30 minutes from downtown Boise and there are some world class resorts within 2-3 hours (Sun Valley, Tamarack, Brundage). If you are from one of the larger cities and looking for a change of pace, you should check Boise out!

More details here: http://www.curiousmedia.com/assets/content/curious-media-web...

Apply: jobs@curiousmedia.com

Amazon New Product Demand Forecasting | Seattle | Full-Time | On-Site ($130-$250+ depending on experience)

Amazon's New Product Demand Forecasting team is responsible for one of the most challenging problems in supply chain optimization: predicting sales for products that have no sales history. This is a uniquely creative space in Forecasting requiring our machine learning models to capture both the nuances of the global consumer marketplace as well as customer behavior on Amazon.

Our team works closely with research scientists to invent new ways to make use of novel data, solve hard engineering problems around scaling and performance in predicting for tens of millions of products, and iterate quickly in order to stay on the cutting edge. I'm looking for an experienced software developer that is comfortable with big data and machine learning and can:

* Design systems that provide a stable base for innovation in a rapidly changing business

* Improve Forecasting algorithms through data-driven analysis and experimentation in our Scala/Spark environment

* Optimize for scalability and performance of both distributed computations and near-metal C++ code

* Learn quickly and keep up with a rapidly changing machine learning and big data landscape

* Communicate their ideas clearly with all members of a diverse team

If this sounds interesting, as the hiring manager I'd love to chat or buy you coffee. Email me (Stefan) at smai@ (amazon.com) with your resume and a brief introduction. (Interview process is 1 phone screen and onsite interview with whiteboard coding and behavioral questions about your experience.)

PassFort | Front-End Engineer & Mobile Engineer | London, UK | ONSITE | https://passfort.com

PassFort is a young and ambitious start-up— you’ll join a team of 6! We’re a seed stage company (we raised £650k at the end of 2015), based in the centre of London, near Southwark tube station.

We're working to solve the problem of digital identity in regulated markets through new technology, great UX and simple solutions.

We use react, es6, redux, mocha and enzyme.

Salary: £40k - £55k with 0.3% - 0.6% equity

https://passfort.com/about#jobs or jobs@passfort.com

Spiceworks | Austin | Full time | Onsite with relocation assistance available

Spiceworks helps millions of IT pros do their jobs with free tools and connect through our online community. Come help us transform IT. We are looking for the following:

- Site Reliability Engineer

- Security Engineer

- Data Engineers and Scientists

- DevOps Automation and Tools Engineer

We have an awesome culture with full benefits, an onsite gym, free drinks & snacks (with breakfast tacos on Monday and bagels on Friday), a weekly development lunch-n-learn and more. We're also ranked as one of the best places to work by Fortune (http://fortune.com/best-medium-workplaces-in-technology/), Glassdoor (http://www.glassdoor.com/Best-Small-and-Medium-Companies-to-...) and have been ranked at a top work place by the Austin American-Statesman six years running (http://www.topworkplaces.com/frontend.php/regional-list/comp...).

Find out more about Spiceworks and see the current openings at http://www.spiceworks.com/jobs