Theory of the Bloch Oscillating Transistor

The Bloch oscillating transistor (BOT) is a device, where single electron current through a normal tunnel junction can be used to enhance Cooper pair current in a mesoscopic Josephson junction leading to signal amplification. In this paper we develop a theory, where the BOT dynamics is described as a two-level system. The theory is used to predict current-voltage characteristics and small-signal response. Transition from stable operation into hysteretic regime is studied. By identifying the two-level switching noise as the main source of fluctuations, the expressions for equivalent noise sources and the noise temperature are derived. The validity of the model is tested by comparing the results with simulations.Comment: 11 pages, 8 figure

RSFQ devices with selective dissipation for quantum information processing

We study the possibility to use frequency dependent damping in RSFQ circuits as means to reduce dissipation and consequent decoherence in RSFQ/qubit circuits. We show that stable RSFQ operation can be achieved by shunting the Josephson junctions with an $RC$ circuit instead of a plain resistor. We derive criteria for the stability of such an arrangement, and discuss the effect on decoherence and the optimisation issues. We also design a simple flux generator aimed at manipulating flux qubits

Kaukojäähdytyksen potentiaali Suomessa

Tiivistelmä. Tässä kandidaatintyössä tutkittiin kaukojäähdytyksen tämänhetkistä tilannetta, sekä sen tulevaisuuden potentiaalia Suomessa. Työssä selvitettiin kaukojäähdytyksen tämänhetkisiä tuotantomääriä ja tapoja, sekä arvioitiin niiden muutoksia tulevaisuudessa. Tarkemmin tarkasteltiin suomessa käytettäviä kaukojäähdytyksen tuotantomenetelmiä, jakelumenetelmiä, sekä tämänhetkisiä tuotantomääriä ja paikkoja. Lopuksi tutkittiin voisiko kaukojäähdytyksellä olla enemmän kysyntää tai sovelluskohteita tulevaisuutta ajatellen, sekä kaukojäähdytyksen tämänhetkisiä ongelmia ja mahdollisia tulevaisuuden ratkaisuja. Tutkimus suoritettiin kirjallisuusselvityksenä. Tutkimustulokset osoittivat, että kaukojäähdytys on ympäristöystävällinen ja energiatehokas tapa tuottaa viilennystä. Kaukojäähdytystä tuotetaan kompressoritekniikalla, absorptiotekniikalla, lämpöpumpuilla, sekä vapaajäähdytyksenä. Näistä yleisimmät tuotantotavat ovat vapaajäähdytys ja lämpöpumppujäähdytys. Kaukojäähdytyksen jakelu tapahtuu maanalaisia verkostoja pitkin kuten kaukolämmönkin. Suomessa kaukojäähdytystä tuotettiin 336 GWh vuonna 2021, joka on kolme kertaa enemmän kuin esimerkiksi vuonna 2010, jolloin kaukojäähdytystä tuotettiin 110 GWh. Suomessa kaukojäähdytystä on saatavilla melkein kaikissa suurkaupungeissa, mutta haja-asutusalueilla sitä ei ole ollenkaan. Suomessa suurimmat kaukojäähdytyksen tuottajat ovat Helen Oy, Turku Energia Oy, Tampereen Sähkölaitos Oy, sekä Fortum Power and Heat Oy. Kaukojäähdytyksen tuotannossa ja jakelussa suurin ongelma on kaukojäähdytysverkkojen hidas ja kallis rakentaminen, mikä rajoittaa niiden rakentamista. Kaukojäähdytyksen kysynnän arvioidaan nousevan tulevaisuudessa, johtuen ilmastonlämpenemisestä ja rakennuskannan kasvusta. Kaukojäähdytyksellä uskotaan olevan suuri rooli tulevaisuuden älykkäissä energiajärjestelmissä, sekä on tutkittu että sitä voitaisiin soveltaa myös harvemmin asutuille alueille laitteistojen hyötysuhteiden parantuessa

Low Noise Current Amplifier Based on Mesoscopic Josephson Junction

We utilize the band structure of a mesoscopic Josephson junction to construct low noise amplifiers. By taking advantage of the quantum dynamics of a Josephson junction, i.e. the interplay of interlevel transitions and the Coulomb blockade of Cooper pairs, we create transistor-like devices, Bloch oscillating transistors, with considerable current gain and high input impedance. In these transistors, correlated supercurrent of Cooper pairs is controlled by a small base current made of single electrons. Our devices reach current and power gains on the order of 30 and 5, respectively. The noise temperature is estimated to be around 1 Kelvin, but it is realistic to achieve TN < 0.1 Kelvin. These devices provide quantum-electronic building blocks that will be useful in low-noise, intermediate-impedance-level circuit applications at low temperatures.Non Peer reviewe

Cardiorespiratory Coupling in Asthmatic Children

The relationship between cardiac and respiratory autonomic control has been suggested to be altered in several respiratory disorders. However, and despite the increasing prevalence of asthma, there are not studies assessing the cardiorespiratory coupling (CRC) with respect to the asthmatic status. Since altered autonomic control has been suggested to play a major role in asthma, in this work overnight CRC was assessed in a group of 67 children who underwent a three-month inhaled corticosteroids treatment. After treatment completion, CRC was reduced (p < 0.005) in the subjects without or with a low risk of asthma, whereas it kept unchanged in those with a worse prognosis, suggesting that an altered interaction between cardiac and respiratory activity might be related with an increased risk of asthma

Survival and mortality of elderly men with localized prostate cancer managed with primary androgen deprivation therapy or by primary observation

Background Androgen deprivation therapy (ADT) remains a primary treatment for localized prostate cancer (PCa) even though there is no evidence that its use is beneficial in the absence of curative treatment. Methods Men aged >= 70 years (n = 16,534) diagnosed with localized PCa from 1985 to 2014 and managed either with primary observation or ADT in the absence of curative treatment were included. The cases were identified from the population-based Finnish Cancer Registry. We estimated the standardized mortality ratios (SMR) for overall mortality by treatment group. We determined the relative risk (RR) of PCa-specific mortality (PCSM) and other-cause mortality between the two treatment groups. Survival was determined using the life table method. Two age groups (70-79 years and >= 80 years) and three calendar time cohorts (1985-1994, 1995-2004, and 2005-2014) were compared following adjustment of propensity score matching between the treatment groups with four covariates (age, year of diagnosis, educational level, and hospital district). Follow-up continued until death or until December 31, 2015. Results Patients in the observation group had lower overall SMRs than those in the ADT group in both age cohorts over the entire study period. PCSM was higher in men aged 70-79 years undergoing primary ADT compared to those managed by observation only (RR: 1.70, 95% confidence interval [CI]: 1.29-2.23 [1985-1994]; RR 1.55, 95% CI: 1.35-1.84 [1995-2004]; and RR 2.71, 95% CI: 2.08-3.53 [2005-2014]); p = 0.005 for periodic trend. A similar trend over time was also observed in men aged > 80 years; (p for age-period interaction = 0.237). Overall survival was also higher among men in their 70's managed by observation compared to those undergoing ADT. Conclusions Primary ADT within four months period from diagnosis is not associated with improved long-term overall survival or decreased PCSM compared to primary conservative management for men with localized PCa. However, this observational study's conclusions should be weighted with confounding factors related to cancer aggressiveness and comorbidities.Peer reviewe

Survival and mortality of elderly men with localized prostate cancer managed with primary androgen deprivation therapy or by primary observation

Background Androgen deprivation therapy (ADT) remains a primary treatment for localized prostate cancer (PCa) even though there is no evidence that its use is beneficial in the absence of curative treatment. Methods Men aged >= 70 years (n = 16,534) diagnosed with localized PCa from 1985 to 2014 and managed either with primary observation or ADT in the absence of curative treatment were included. The cases were identified from the population-based Finnish Cancer Registry. We estimated the standardized mortality ratios (SMR) for overall mortality by treatment group. We determined the relative risk (RR) of PCa-specific mortality (PCSM) and other-cause mortality between the two treatment groups. Survival was determined using the life table method. Two age groups (70-79 years and >= 80 years) and three calendar time cohorts (1985-1994, 1995-2004, and 2005-2014) were compared following adjustment of propensity score matching between the treatment groups with four covariates (age, year of diagnosis, educational level, and hospital district). Follow-up continued until death or until December 31, 2015. Results Patients in the observation group had lower overall SMRs than those in the ADT group in both age cohorts over the entire study period. PCSM was higher in men aged 70-79 years undergoing primary ADT compared to those managed by observation only (RR: 1.70, 95% confidence interval [CI]: 1.29-2.23 [1985-1994]; RR 1.55, 95% CI: 1.35-1.84 [1995-2004]; and RR 2.71, 95% CI: 2.08-3.53 [2005-2014]); p = 0.005 for periodic trend. A similar trend over time was also observed in men aged > 80 years; (p for age-period interaction = 0.237). Overall survival was also higher among men in their 70's managed by observation compared to those undergoing ADT. Conclusions Primary ADT within four months period from diagnosis is not associated with improved long-term overall survival or decreased PCSM compared to primary conservative management for men with localized PCa. However, this observational study's conclusions should be weighted with confounding factors related to cancer aggressiveness and comorbidities.Peer reviewe

Cancer Incidence and Mortality in the Oldest Old: a Nationwide Study in Finland

The world's population is aging rapidly. This study reports the burden of cancer in the oldest old (≥85 years) in Finland in 1953-2017 and estimates age-specific cancer rates in the old population (65-99 years) in 1988-2017. The Finnish Cancer Registry provided data on all cancer diagnoses, cancer deaths and other deaths in cancer patients in Finland in 1953-2017. Between 1953-1957 and 2013-2017, the proportion of incident cancers in those aged ≥85 years increased from 1.5% to 9.6% (597 to 15,360 new cases), and in 2013-2017, more new cancers were diagnosed at age ≥85 years than age <50 years. Cancer incidence and excess mortality attributable to cancer peaked at age 85-94 years and declined subsequently, whereas cancer-specific mortality continued to increase or plateaued. Due to demographic changes, the number of new cancers in the oldest old has increased substantially in Finland, and currently, nearly one in 10 cancers are diagnosed in this age group. The increasing cancer burden in the oldest old poses a major challenge for healthcare and needs to be addressed in designing clinical research and reporting of cancer registries. In old populations with competing risks of death, we propose excess cancer mortality as a measure of cancer-related mortality.Peer reviewe