I-mode studies at ASDEX Upgrade: L-I and I-H transitions, pedestal and confinement properties

The I-mode is a plasma regime obtained when the usual L-H power threshold is high, e.g. with unfavourable ion B ∇ direction. It is characterised by the development of a temperature pedestal while the density remains roughly as in the L-mode. This leads to a confinement improvement above the L-mode level which can sometimes reach H-mode values. This regime, already obtained in the ASDEX Upgrade tokamak about two decades ago, has been studied again since 2009 taking advantage of the development of new diagnostics and heating possibilities. The I-mode in ASDEX Upgrade has been achieved with different heating methods such as NBI, ECRH and ICRF. The I-mode properties, power threshold, pedestal characteristics and confinement, are independent of the heating method. The power required at the L-I transition exhibits an offset linear density dependence but, in contrast to the L-H threshold, depends weakly on the magnetic field. The L-I transition seems to be mainly determined by the edge pressure gradient and the comparison between ECRH and NBI induced L-I transitions suggests that the ion channel plays a key role. The I-mode often evolves gradually over a few confinement times until the transition to H-mode which offers a very interesting situation to study the transport reduction and its link with the pedestal formation. Exploratory discharges in which n = 2 magnetic perturbations have been applied indicate that these can lead to an increase of the I-mode power threshold by flattening the edge pressure at fixed heating input power: more heating power is necessary to restore the required edge pressure gradient. Finally, the confinement properties of the I-mode are discussed in detail.European Commission (EUROfusion 633053

Orthorhombic versus monoclinic symmetry of the charge-ordered state of NaV2O5

High-resolution X-ray diffraction data show that the low-temperature superstructure of alpha-NaV2O5 has an F-centered orthorhombic 2a x 2b x 4c superlattice. A structure model is proposed, that is characterized by layers with zigzag charge order on all ladders and stacking disorder, such that the averaged structure has space group Fmm2. This model is in accordance with both X-ray scattering and NMR data. Variations in the stacking order and disorder offer an explanation for the recently observed devils staircase of the superlattice period along c.Comment: REVTEX, 4 pages including 2 figures, shortened, submitted to PR

Ab initio evaluation of the charge-ordering in α′NaV2O5\alpha^\prime NaV_2O_5

We report {\it ab initio} calculations of the charge ordering in $\alpha^\prime NaV_2O_5$ using large configurations interaction methods on embedded fragments. Our major result is that the $2p_y$ electrons of the bridging oxygen of the rungs present a very strong magnetic character and should thus be explicitly considered in any relevant effective model. The most striking consequence of this result is that the spin and charge ordering differ substantially, as differ the experimental results depending on whether they are sensitive to the spin or charge density.Comment: 4 page

Ferroelectric soft mode of polar ZnTiO3 investigated by Raman spectroscopy at high pressure

We explore the vibrational behavior and stability of ferroelectric ZnTiO3 under high pressure by Raman spectroscopy and second-harmonic-generation (SHG) measurements. Ab initio lattice-dynamics calculations have been employed to solve a controversy concerning the phonon-dispersion relations of ZnTiO3 and to carry out an assignment of the Raman modes. A ferroelectric to paraelectric phase transition has been observed both by Raman spectroscopy and SHG at 20.8 GPa. Contrary to LiNbO3, the ferroelectric soft mode of ZnTiO3 has been found to be the A1(2) and not the A1(1) mode. The calculated eigenvectors show that the A1(2) mode of ferroelectric ZnTiO3 is an antiphase vibration of the Ti atom against the oxygen framework, similar to the soft modes observed in ferroelectric perovskites. The SHG signal of ZnTiO3 has been found to be independent of the grain size below the phase transition, indicating that ZnTiO3 is a phase-matchable compound

Lattice vibrations of alpha'-NaV_2O_5 in the low-temperature phase. Magnetic bound states?

We report high resolution polarized infrared studies of the quarter-filled spin ladder compound alpha'-NaV_2O_5 as a function of temperature (5K <= T <= 300K). Numerous new modes were detected below the temperature T_c=34K of the phase transition into a charge ordered nonmagnetic state accompanied by a lattice dimerization. We analyse the Brillouin zone (BZ) folding due to lattice dimerization at T_c and show that some peculiarities of the low-temperature vibrational spectrum come from quadruplets folded from the BZ point (1/2, 1/2, 1/4). We discuss an earlier interpretation of the 70, 107, and 133cm-1 modes as magnetic bound states and propose the alternative interpretation as folded phonon modes strongly interacting with charge and spin excitations.Comment: 15 pages, 13 Postscript figure

Програма проходження практики студентами ІІ курсу (денної форми навчання) спеціальності 6.030509 “Облік і аудит”

Організаційна практика для студентів спеціальності 6.030509 «Облік і аудит» організовується відповідно до навчального плану Університету. Метою практики є закріплення, розширення та поглиблення теоретичних знань, практичних вмінь та навичок з дисциплін, що вивчаються, формування зацікавленості до майбутньої професіональної діяльності, ознайомлення з методикою роботи бухгалтера та аудитора в управлінських структурах організації для вирішення завдань при різних практичних ситуаціях. Керівництво практикою здійснюється викладачами кафедри бухгалтерського обліку та аудиту, які контролюють своєчасне прибуття студентів на місце практики, хід її виконання, консультують практикантів щодо програми і матеріалів практики, допомагають у вирішенні питань із забезпечення нормальних умов праці. Про результати перевірки керівник робить запис у щоденнику та інформує деканат. Під час практики студент зобов’язаний своєчасно і якісно виконувати завдання, передбачені програмою практики, опановувати прийоми обліку, дотримуватись правил внутрішнього розпорядку, не порушувати трудову дисципліну, сприяти виконанню завдань, які стоять перед навчальним закладом.Організаційна практика є складовою частиною навчально-виховного та науково-дослідного процесу підготовки фахівців з обліку і аудиту і має на меті формування у них практичних навичок самостійної роботи у сфері бухгалтерського обліку, контролю, аналізу і аудиту та умінь працювати за обраною спеціальністю у системі ринкового господарювання

Overview of progress in European medium sized tokamaks towards an integrated plasma-edge/wall solution

Integrating the plasma core performance with an edge and scrape-off layer (SOL) that leads to tolerable heat and particle loads on the wall is a major challenge. The new European medium size tokamak task force (EU-MST) coordinates research on ASDEX Upgrade (AUG), MAST and TCV. This multi-machine approach within EU-MST, covering a wide parameter range, is instrumental to progress in the field, as ITER and DEMO core/pedestal and SOL parameters are not achievable simultaneously in present day devices. A two prong approach is adopted. On the one hand, scenarios with tolerable transient heat and particle loads, including active edge localised mode (ELM) control are developed. On the other hand, divertor solutions including advanced magnetic configurations are studied. Considerable progress has been made on both approaches, in particular in the fields of: ELM control with resonant magnetic perturbations (RMP), small ELM regimes, detachment onset and control, as well as filamentary scrape-off-layer transport. For example full ELM suppression has now been achieved on AUG at low collisionality with n  =  2 RMP maintaining good confinement HH(98,y2)≈0.95. Advances have been made with respect to detachment onset and control. Studies in advanced divertor configurations (Snowflake, Super-X and X-point target divertor) shed new light on SOL physics. Cross field filamentary transport has been characterised in a wide parameter regime on AUG, MAST and TCV progressing the theoretical and experimental understanding crucial for predicting first wall loads in ITER and DEMO. Conditions in the SOL also play a crucial role for ELM stability and access to small ELM regimes.Integrating the plasma core performance with an edge and scrape-off layer (SOL) that leads to tolerable heat and particle loads on the wall is a major challenge. The new European medium size tokamak task force (EU-MST) coordinates research on ASDEX Upgrade (AUG), MAST and TCV. This multi-machine approach within EU-MST, covering a wide parameter range, is instrumental to progress in the field, as ITER and DEMO core/pedestal and SOL parameters are not achievable simultaneously in present day devices. A two prong approach is adopted. On the one hand, scenarios with tolerable transient heat and particle loads, including active edge localised mode (ELM) control are developed. On the other hand, divertor solutions including advanced magnetic configurations are studied. Considerable progress has been made on both approaches, in particular in the fields of: ELM control with resonant magnetic perturbations (RMP), small ELM regimes, detachment onset and control, as well as filamentary scrape-off-layer transport. For example full ELM suppression has now been achieved on AUG at low collisionality with n = 2 RMP maintaining good confinement H-H(98,H-y2) approximate to 0.95. Advances have been made with respect to detachment onset and control. Studies in advanced divertor configurations (Snowflake, Super-X and X-point target divertor) shed new light on SOL physics. Cross field filamentary transport has been characterised in a wide parameter regime on AUG, MAST and TCV progressing the theoretical and experimental understanding crucial for predicting first wall loads in ITER and DEMO. Conditions in the SOL also play a crucial role for ELM stability and access to small ELM regimes.Peer reviewe

Views and experiences of people with intellectual disabilities regarding intimate relationships: a qualitative metasynthesis

The aims of this review were to systematically identify, critically appraise and synthesize the results of existing qualitative literature exploring the views and experiences of intimate relationships amongst people with intellectual disabilities. Fourteen peer-reviewed articles were identified through a systematic search of eight databases, reference lists, citations, and relevant journals. The identified articles were appraised for quality, then synthesized using a metaethnography approach. No study met all quality criteria and references to ethical approval were often lacking. Interpretation of the findings suggested three key themes: the meaning of intimate relationships, external constraints and facilitators, and managing external constraints. Though many people with intellectual disabilities desire and benefit from intimate relationships, they experience restrictions that others do not, which can lead to isolation and loneliness. Intimate relationships are not always necessarily linked with sexual behavior; therefore, intimate relationships warrant their own focus in future research, as well as in education and training for people with intellectual disabilities and their caregivers. Within this, a commitment to transparency over research processes is needed, in particular with reference to how ethical approval was obtained, since this has been a shortcoming of research with this focus to date