## Guðmundur Helgason (01/06/17)

Thesis presentation in Master of Applied Statistics (MAS)

### Guðmundur Helgason

Titill: Hversu lengi þarf ég að bíða? Forspárlíkön fyrir biðtíma í þjónustuveri CCP

Location: V-157, VRII

Time: Thursday 1. June at14:00.

### Abstrat:

Í þessari rannsókn, með hjálp ýmissa tölfræðiaðferða, spáum við fyrir um biðtíma eftir svari við tölvupósti með gögnum frá þjónustuveri CCP, framleiðanda tölvuleiksins EVE Online. Að mestu leyti er notast við tvíkosta tölfræðilíkön þar sem spáð er fyrir um hvort að svar sé gefið fyrir ákveðinn tímapunkt eða ekki. Samfelldar aðferðir eru þó einnig notaðar, bæði til að spá fyrir um biðtíma í sjálfu sér og hvort svar sé gefið fyrir ákveðinn tíma eða ekki. Auk greiningarlegra aðferða til forspáar er einnig notast við einfaldari empírískar aðferðir til að meta dreifingu biðtíma og líkindi á svari eftir ákveðinn tíma. Tiltækar rannsóknir á sviði þjónustuvera, gæða í þjónustu, áhrifa þess að bíða eftir þjónustu og aðferða sem notast hefur verið við til að spá fyrir um biðtíma eru skoðaðar. Aðferðirnar sem notast var við til biðtíma forspáar eru bornar saman, kostir þeirra og gallar ræddir, auk hugsanlegra hagnýtra eiginleika.

Leiðbeinendur:

Anna Helga Jónsdóttir

Matthías Kormáksson

Prófdómari: Thor Aspelund

## Stella Kristín Hallgrímsdóttir

Thesis presentation in Master of Applied Statistics (MAS)

### Stella Kristín Hallgrímsdóttir

Title: Samband veðurs og komufjölda á bráðamóttökur Landspítala

Location: V-157, VRII

Time: Monday 29. May at 14:00.

### Abstract:

The objective of this project is to study the seasonal and weekly fluctuations in number of arrivals to the emergency departments of the University Hospital of Iceland and also to assess the influence of weather on the number of arrivals. Four emergency departments were examined; the Emergency Department in Fossvogur, the Emergency Unit in the Children‘s Hospital Department, Hjartagátt which is the emergency department for people with suspected acute heart problems, and the Psychiatry Emergency Department. The weather variables that were mostly looked into are temperature, wind speed, precipitation and cloudiness. Seasonal fluctuations were modeled with sine and cosine waves and with the help of linear regression a new variable was made that describes the seasonal fluctuations and linear increase in the number of arrivals. A few ARIMA models were built to predict the number of arrivals in the Emergency Department in Fossvogur and in the Children‘s Emergency Department. The models were compared to find the best prediction model for each department. To assess whether weather affects the number of arrivals in the emergency departments, the weather variables were added one by one to the best prediction model for each department to see if the model‘s prediction root-mean squared error (RMSE) decreases when information about weather is added to the model. Principal components analysis was also used to combine the weather variables into fewer new variables. The new variables were then added to the ARIMA models to assess their effect on the goodness of the models. The results show that adding the weather information slightly decreases prediction RMSE in the Emergency Department in Fossvogur but increases it for the Children‘s Emergency Department. That both applies to when each weather variable was looked into separately and when the principal components were used. Therefore, it can be concluded that weather does not affect the number of arrivals to the Children‘s Emergency Department but it has a minor effect on the number of arrivals to the Emergency Department in Fossvogur. Furthermore, the results show that a good prediction model for the number of arrivals to the emergency departments can be developed only using calendar variables.

Advisors: Dr. Sigrún Helga Lund and Dr. Tryggvi Helgason

Examiner: Dr. Ólafur Pétur Pálsson

## Arnbjörg Soffía Árnadóttir (06/10/16)

Meistaraprófsfyrirlestur

### Arnbjörg Soffía Árnadóttir

Title: Group actions on infinite digraphs and the suborbit function

Location: Naustið, Endurmenntun.

Time: Thursday October 6. 2016 at 16:00.

### Abstract:

We study infinite directed graphs, using group actions. We start by defining a group homomorphism called the suborbit function. Then we use this homomorphism to investigate various properties of infinite digraphs, including homomorphic images, highly arc transitive digraphs, Cayley-Abels digraphs and the growth of digraphs.

Advisors: Professor Rögnvaldur G. Möller and professor Jón Ingólfur Magnússon at Science Institute, University of Iceland.

Examiner: Professor emeritus Peter M. Neumann The Queen’s College, Oxford University.

## Adam Timar

Math Colloquium

### Speaker: Adam Timar, Renyi Institute, Budapest

Title: Allocation rules for the Poisson point process

Location: Árnagarður 101.

Time: Friday, June 3, at 13:20-14:20.

### Abstract:

Consider the Poisson point process in Euclidean space. We are interested in functions on this random point set whose value in each configuration point is given by some “local” rule (no “central planning”). One example is the so-called allocation problem, where we want to partition R^d to sets of measure 1 and match them with the point process, in a translation equivariant way. We want to make the allocated set optimal in some sense (e.g., the distribution of the diameter shows fast decay). We will present some allocation schemes, among them one with an optimal tail, which is joint work with R. Marko.

## PhD Position in Theoretical Physics

Applications are invited for a PhD position in theoretical high-energy physics at the University of Iceland with a starting date in Fall 2016. The position is funded by a grant from the Icelandic Research Fund.

The successful candidate will work in the area of quantum field theory and string theory with emphasis on gauge theory/gravity duality and holographic models for strongly coupled field theories. A master degree, or equivalent, in theoretical physics is required.

The application deadline is May 6, however applications will continue to be accepted until the position is filled.

Applications should be submitted electronically to

https://academicjobsonline.org/ajo/jobs/7202

and should include a CV, transcripts from undergraduate and master studies, a short description of research interests, and names and e-mail addresses of two referees, who have agreed to provide recommendation letters.

For further information please contact:

Ass. Prof. Valentina Giangreco Puletti (e-mail: vgmp[at]hi.is) or

Prof. Lárus Thorlacius (e-mail: lth[at]hi.is)

Faculty of Physical Sciences

University of Iceland

## The naked Pure Mathematician

Finnur Lárusson, our colleague at the University of Adelaide in Australia and a former student at the University of Iceland, recently gave a very interesting talk about pure mathematics called “The naked Pure Mathematician”. This is his Inaugural Lecture as a Professor of Pure Mathematics.

## Assistant Professor in applied mathematics

The Faculty of Physical Sciences in the School of Engineering and Natural Sciences at the University of Iceland, seeks applicants to fill a full tenure-track position of Assistant Professor in applied mathematics.

Applicants should possess innovation and organizational skills in order to build strong research capabilities and research related studies in applied mathematics, in collaboration with other faculties within the School of Engineering and Natural Sciences. The faculty has recently started a BSc degree program in applied mathematics and the successful applicant will be expected to further its development. She or he will also teach mathematics courses both at undergraduate and postgraduate level.

The successful candidate should be active in research, preferably in areas of applied mathematics that are connected with mathematical analysis, for example numerical solutions of ordinary and partial differential equations, dynamical systems, numerical analysis and approximation theory. It is desirable that applicants have experience of applying mathematics to other areas.

The successful candidate will be able to hire a postdoctoral researcher for two years.

Continue reading 'Assistant Professor in applied mathematics'»

## Research Specialist in Mathematics or Mathematical Physics at The Science Institute

The Mathematics Division at the Science Institute seeks applicants to fill a full Research Specialist position in the area of mathematics or mathematical physics.

The Research Specialist is expected to conduct research in mathematics or mathematical physics. Applicants must have a strong research background in one or both of the above-mentioned fields. It will be taken into consideration how well the applicants research fits with the areas emphasized by the Mathematics Division.

Teaching is not a mandatory part of the position, however possible teaching at the Faculty of Physical Sciences by Research Specialists at the Science Institute is in accordance with rules no. 685/2011 of the Science Institute, University of Iceland.

## Postdoctoral position at the University of Iceland

There is a three-year postdoctoral position available at the University of Iceland financed by The Icelandic Centre for Research, rannis.is.

The research project is called: *Complex Analysis with Emphasis on Pluripotential Theory*.

We are mainly interested in the theory of holomorphic and plurisubharmonic functions and we are especially interested in applications of the

functions.

We are looking for a candidate who has completed a PhD within the last 5 years or is close to defending a PhD thesis. Her/his specialization and interests should be in this area.

Everyone is welcome to contact us for further information.

Applications should be sent to us directly by e-mail, including a CV, list of publication or an abstract of a planned PhD thesis, and a research statement. The names and e-mail addresses of two referees should be included, a thesis advisor should be one of them.

The application deadline is December 31. All applications will be answered.

The starting time for the position is a matter of agreement.

Benedikt Steinar Magnússon <bsm [at] hi.is> and

Ragnar Sigurdsson <ragnar [at] hi.is>.