Bound states and entanglement in the excited states of quantum spin chains

We investigate entanglement properties of the excited states of the spin-1/2 Heisenberg (XXX) chain with isotropic antiferromagnetic interactions, by exploiting the Bethe ansatz solution of the model. We consider eigenstates obtained from both real and complex solutions ("strings") of the Bethe equations. Physically, the former are states of interacting magnons, whereas the latter contain bound states of groups of particles. We first focus on the situation with few particles in the chain. Using exact results and semiclassical arguments, we derive an upper bound S_MAX for the entanglement entropy. This exhibits an intermediate behavior between logarithmic and extensive, and it is saturated for highly-entangled states. As a function of the eigenstate energy, the entanglement entropy is organized in bands. Their number depends on the number of blocks of contiguous Bethe-Takahashi quantum numbers. In presence of bound states a significant reduction in the entanglement entropy occurs, reflecting that a group of bound particles behaves effectively as a single particle. Interestingly, the associated entanglement spectrum shows edge-related levels. At finite particle density, the semiclassical bound S_MAX becomes inaccurate. For highly-entangled states S_A\propto L_c, with L_c the chord length, signaling the crossover to extensive entanglement. Finally, we consider eigenstates containing a single pair of bound particles. No significant entanglement reduction occurs, in contrast with the few-particle case.Comment: 39 pages, 10 figure. as published in JSTAT. Invited submission to JSTAT Special Issue: Quantum Entanglement in Condensed Matter Physic

The influence of a transport process on the epidemic threshold

By generating transient encounters between individuals beyond their immediate social environment, transport can have a profound impact on the spreading of an epidemic. In this work, we consider epidemic dynamics in the presence of the transport process that gives rise to a multiplex network model. In addition to a static layer, the (multiplex) epidemic network consists of a second dynamic layer in which any two individuals are connected for the time they occupy the same site during a random walk they perform on a separate transport network. We develop a mean-field description of the stochastic network model and study the influence the transport process has on the epidemic threshold. We show that any transport process generally lowers the epidemic threshold because of the additional connections it generates. In contrast, considering also random walks of fractional order that in some sense are a more realistic model of human mobility, we find that these non-local transport dynamics raise the epidemic threshold in comparison to a classical local random walk. We also test our model on a realistic transport network (the Munich U-Bahn network), and carefully compare mean-field solutions with stochastic trajectories in a range of scenarios.Comment: Version as to appear in the Journal of Mathematical Biology with revised figure

Business model innovation analysis of Tammsaare OÜ

Magistritöö Ökonoomika ja ettevõtluse õppekavalKeerulised ajad põllumajanduses on sundinud piimatootjaid viimastel aastatel oma tegevusi mitmeid kordi üle vaatama. Uuenduste vajadust on tunnetatud ka peamiselt piimakasvatusega tegelevas ettevõttes Tammsaare OÜ, mis on käesoleva uurimustöö objektiks. Lisaks piimatootmisele tegeletakse ettevõttes teravilja- ja rapsikasvatusega, mis ei ole viimastel aastatel piisavalt häid tulemusi andnud. Seetõttu on antud uurimustöö peamine eesmärk analüüsida ettevõtte ärimudelit ja selle innovatsiooni võimalusi taimekasvatuse valdkonnas. Tammsaare OÜ tegevuse analüüsimisel toetutakse Osterwalder-i ja Piqnuer-i (2010) loodud ärimudeli lõuendi kontseptsioonile, mille abil defineeritakse ettevõtte tänane äriloogika. Ärimudeli loomisele järgneb innovatsiooni analüüs, mille raames keskendutakse osturohusöötadele ja ostuteraviljale kui alternatiivile. Peamised uurimustöös kasutatud andmed pärinevad Tammsaare OÜ raamatupidamise dokumentidest, erinevatest riigi registritest ning vastavaid teenuseid pakkuvate eraettevõtete poolt väljastatud hinnapakkumistest. Tammsaare OÜ-s kulutati 2017. a rohusöötade tootmisele 353 197,3 €. Sööda sisseostmisel oleks arvestuslik kogukulu tulnud 349 292,7 €. Teravilja- ja rapsikasvatuse kogukulu 2017. a oli 268 755,9 €. Teravilja- ja rapsikasvatuse lõpetamisel ja ostuteraviljale üleminekul oleks arvestuslik kogukulu tulnud 198 975,4 €. Samas ei oleks teravilja- ja rapsikasvatuse lõpetamisel võimalik täita teatud ettevõtte poolt kasutatavate põllumajandustoetuste nõudeid, mille tulemusel väheneks eeldatav toetustest saadav tulu rohkem kui 100 000 € võrra. Samuti kaoks ostusöötadele üleminekul võimalus teraviljamüügiks. Teravilja müügitulu 2017.a oli aga 113 908,4 €. Analüüsi tulemusena tuli kogukulu ostusöötade ja teenustööde kasutamise korral 140 516 € võrra suurem, kui see oli 2017.a. Seega ei oleks vastav ärimudeli innovatsioon ettevõtte seisukohast põhjendatud. Tulevasi uuringuid silmas pidades võiks ettevõte kaaluda teraviljakasvatuse põhjalikumat analüüsi s.h Tammsaare OÜ potentsiaali teenustööde pakkumiseks antud valdkonnas.Difficult times in agriculture in last couple of years have forced milk producers to overlook their activities and plans. The need for changes has also been felt by Tammsaare OÜ, a company that mainly focuses on dairy production. Therefore, Tammsaare OÜ is the object of this research. In addition to milk production, the company produces grain and rapeseed, an area that has not been as successful in recent years. Thus, the aim of this research is to analyse company’s business model and its opportunities for innovation in the field of horticulture. In the analysis of Tammsaare OÜ, the business model Canvas, made by Osterwalder and Piqnuer (2010) is used. The canvas helps to define the business logic of the company. The creation of business model is followed by analysis of its potential for innovation. The innovation focuses on purchased services in forage and grain production as an alternative. This research is based on the data from Tammsaare OÜ accounting files, various databases managed by the state, and the price offers of private companies that provide needed services. In 2017 Tammsaare OÜ spent on the production of forage € 353 197, 3. If the feed had been purchased as a service then the total cost would have been € 349 292, 7. The total cost of grain and rapeseed production in 2017 was € 268 755, 9. If the company had decided to finish the production of grain and rapeseed and used purchased grain as an alternative, then the total cost would have been € 198 975, 4. However, if Tammsaare OÜ terminates crop and rapeseed production, certain requirements of agricultural subsidies would not be met. As a consequence, the benefits of the subsidies would decrease more than € 100 000. In addition, there would be no sales revenue from the grain production. The sales revenue of the grain production in 2017 was € 113 908, 4. The results of this analysis indicate that if the grain and rapeseed production and forage harvesting is terminated, the cost of purchased services would be € 140 516, 0 higher than it was in 2017. Therefore, the business model innovation analysed is not fully justified. Further research in Tammsaare OÜ should focus on the analysis of grain and rapeseed production inc. analysis of agricultural services that could be provided in the market

The analysis of Mäelaari Ltd sheepfarm

Antud uurimuse eesmärk on analüüsida sööda tootmist OÜ Mäelaari talus. Talu peamiseks tegevusvaldkonnaks on lambakasvatus. Ettevõtte kõige suurem kuluartikkel on söödatootmine. Seega on uurimustöös enim tähelepanu pööratud erienavete silotootmistehnolooogiate võrdlemisele. Kuigi talul on olemas virsnsilo tootmiseks vajalik haagiskogur, on viimastel aastatel toodetud vaid ruloonsilo. Käesoleva bakalaureuse töö hüpoteesiks on väide: virnsilo tootmine on tulusam, kui ruloonsilo valmistamine. Hüpoteesi tõestamiseks või ümberlükkamiseks koguti 2013. aasta vältel andmeid OÜ Mäelaari talust. Ruloonsilo tootmise analüüsimiseks vajalikud andmed pärinevad ettevõttest, haagiskoguriga valmistatud virnsilo tootmiseks vajalikud andmed põhinevad vastaval erialasel kirjandusel. Töö tulemustest selgus, et haagiskoguriga toodetud virnsilo omahind oli 13 % odavam ruloonsilo valmistamisest. Lisaks sellele oli tehnoloogiatel erinev ajakulu, mis taaskord kinnitas haagiskoguri produktiivsust. Arvestades, et talu on juba soetanud endale haagiskoguri, usun, et antud tulemused osutuvad ettevõttele kasulikuks.The aim of this research is to analyse food production in a sheep farm called Mäelaari Ltd. The primary activity of the enterprise is sheep husbandry. The biggest item of expenditure is food production. Therefore, the emphasis has been put on different technologies of silage production. Although the farm has a forage wagon for clamp silage, during the last years only big bale silage has been produced. The hypothesis of the study is that the technology of clamp silage is more cost-effective. The empirical analyses to test this hypothesis are based on data drawn from the sheep farm Mäelaari Ltd in 2013. The variables related to the technology of big bale silage were collected from the enterprise. The data for clamp silage making with forage wagons was obtained from previous studies. The findings of the study showed that the silage made with big bale technology was 13 % cheaper than the clamp silage made with a forage wagon. In addition to that, the amount of time spent on the processes differed, with the forage wagon being more productive. The results of the research are useful for the farm, particularly considering the availability of forage wagon technology

Green recovery tracker : tracking the contribution of national covid-19 recovery efforts towards a climate neutral EU ; summary report

The idea for the Green Recovery Tracker was born in spring 2020 when governments started making announcements on economic Corona recovery measures. From a climate and resilience perspective it is key that those recovery packages, investments and subsidies are in line with long-term climate and sustainability targets. Thus, recovery packages should not only boost the economy in the short-term, but also strike the path to a just transition towards climate neutrality. Against this background, Wuppertal Institute and E3G have launched the Green Recovery Tracker project in late summer 2020 to shed light on the following questions: What can be considered an effective green recovery? What are good examples, which can be used as an inspiration for recovery programs aiming to support sustainable development? Where do the individual Member States stand with respect to aligning their recovery activities with the climate policy agenda? In this report, you will find our Methodology as well our Policy Briefing highlighting our key takeaways of our country and sectoral analyses. It further includes a section on "What can we learn from our experience with the Green Recovery Tracker?". The briefing concludes with a "Guidance for future funding programs and achieving climate targets overall"

Strategische Ansätze für die Gestaltung des Strukturwandels in der Lausitz : was lässt sich aus den Erfahrungen in Nordrhein-Westfalen und dem Rheinischen Revier lernen? ; Endbericht

Durch den zu erwartenden Rückgang der Braunkohleverstromung in Deutschland wird der Strukturwandel in der Lausitz weiter beschleunigt werden. Die Energiewende erfordert also eine konsistente strukturpolitische Flankierung, für diejenigen Regionen, die bisher ökonomisch stark vom Braunkohlebergbau (inklusive Vorketten und Folgeindustrien) abhänging sind. Vor diesem Hintergrund hat die Brandenburger Landtagsfraktion von Bündnis 90 / Die Grünen das Wuppertal Institut beauftragt, erste Empfehlungen für strategische Ansätze einer präventiven Strukturpolitik in der Lausitz zu entwickeln. Die Kurzstudie nimmt besonders in den Blick, welche Erkenntnisse sich aus den Erfahrungen mit dem Strukturwandel in Nordrhein-Westfalen und insbesondere dem Rheinischen Revier für die Gestaltung des Strukturwandels in der Lausitz ableiten lassen

Loote kromosoomhaiguste esimese trimestri sõeluuringu tulemused Eestis kahe aasta jooksul

Taust ja eesmärgid. Loote kromosoomhaiguste avastamiseks on Eestis alates 1995. aastast kasutatud erinevaid sõeluuringuid. 2016. aastast kehtinud sünnieelse diagnostika juhendi kohaselt on esimese trimestri kombineeritud sõeluuring kuni praeguseni olnud esmane sünnieelne kromosoomhaiguste sõeluuring. Käesoleva töö eesmärk oli hinnata esimese trimestri kombineeritud sõeluuringu efektiivsust kromosoomhaiguste avastamisel kaheaastase (2017–2018) uuringu alusel.Metoodika. Uuriti rasedaid, kes pöördusid kromosoomhaiguste sõeluuringuks Ida-Tallinna Keskhaiglasse (ITK) või Tartu Ülikooli (TÜ) Kliinikumi. Sõeluuring tehti Eesti sünnieelse diagnostika juhendi standardiseeritud protokolli alusel.Tulemused. Kombineeritud sõeluuring tehti 14 566 rasedal. Sõeltest oli positiivne 3,54%-l naistest. Trisoomia 21 avastamise määr sünni eel oli 94% (95% usaldusvahemik (uv) 84,09–97,98%), trisoomia 18 (95% uv 74,12–100%) ja trisoomia 13 avastati 100% (95% uv 43,85–100%). Valepositiivsuse määr oli 3,12%. Sõeluuringu tundlikkus oli 95,38% (95% uv 86,24–98,80%), spetsiifilisus 96,86% (95% uv 96,56–97,13%), positiivne ennustatav väärtus 11,99% (95% uv 9,38–15,18%), negatiivne ennustatav väärtus 99,97% (95% uv 99,93–99,99%).Järeldused. Esimese trimestri kombineeritud sõeluuring on efektiivne meetod kromosoomhaiguste sünnieelseks avastamiseks. Trisoomia 21 avastamise määr on suurem võrreldes eelmise Eestis korraldatud uuringu tulemustega. Üleminek esimese trimestri kombineeritud sõeluuringule oli Eestis õigustatud.Uuringuks on andnud loa Tartu Ülikooli inimuuringute eetika komitee (protokoll 263/M-19 17.10.2016)

Changing storminess and global capture fisheries

This is the author accepted manuscript. The final version is available from Nature Publishing Group via the DOI in this record.Climate change-driven alterations in storminess pose a signifcant threat to global capture fsheries. Understanding how storms interact with fshery social-ecological systems can inform adaptive action and help to reduce the vulnerability of those dependent on fisheries for life and livelihood.N.C.S. acknowledges the financial support of the UK Natural Environment Research Council (NERC; GW4+ studentship NE/L002434/1), Centre for Environment, Fisheries and Aquaculture Science and Willis Research Network