484 research outputs found
Response of arum lily calli to culture filtrate of Pectobacterium carotovorum subsp. carotovorum
This report demonstrated that culture filtrate of Pectobacterium carotovorum ssp. carotovorum isolate ZT0505, the pathogen of bacterial soft rot disease of arum lily (Zantedeschia sp.), contained extracellular enzymes and caused arum lily leaf tissue and callus maceration. Arum lily leaf tissue and callus sensitivity to culture filtrate coincided with the host susceptibility to the pathogen. The rates of survival of callus pieces were determined after exposure for various times to culture filtrate. Survival of callus pieces (%) increased with reduction of exposure time from 20 to 14 h and from 14 to 8 h. One out of 30 callus pieces was still viable after 3 cycles of 8 h exposure. Subsequently, the surviving cells in this callus pieces proliferated and differentiated into shoots. Based on this initial work, the callus screening using culture filtrate as selection agent may be useful for in vitro selection of soft rot resistant germplasm in arum lily
The goal dependent automaticity of drinking habits
In recent treatments of habitual social behaviour, habits are conceptualised as a form of goal-directed automatic behaviour that are mentally represented as goal-action links. Three experiments tested this conceptualisation in the context of studentsā drinking (alcohol consumption) habits. Participants were randomly assigned to conditions where either a goal related to drinking behaviour (socialising) was activated, or an unrelated goal was activated. In addition, participantsā drinking habits were measured. The dependent variable in Experiments 1 and 2 was readiness to drink, operationalised by speed of responding to the action concept ādrinkingā in a verb verification task. Experiment 3 used uptake of a voucher to measure drinking behaviour. Findings supported the view that when habits are established, simply activating a goal related to the focal behaviour automatically elicits that behaviour. These findings are consistent with a goal-dependent conception of habit. Possibilities for interventions designed to attenuate undesirable habitual behaviours are considered
Rewards enhance proactive and reactive control in adolescence and adulthood
Cognitive control allows the coordination of cognitive processes to achieve goals. Control may be sustained in anticipation of goal-relevant cues (proactive control) or transient in response to the cues themselves (reactive control). Adolescents typically exhibit a more reactive pattern than adults in the absence of incentives. We investigated how reward modulates cognitive control engagement in a letter array working memory (WM) task in 30 adolescents (12-17 years) and 20 adults (23-30 years) using a mixed block- and event-related functional magnetic resonance imaging design. After a Baseline run without rewards, participants performed a Reward run where 50% trials were monetarily rewarded. Accuracy and reaction time (RT) differences between Reward and Baseline runs indicated engagement of proactive control, which was associated with increased sustained activity in the bilateral anterior insula (AI), right dorsolateral prefrontal cortex (PFC) and right posterior parietal cortex (PPC). RT differences between Reward and No reward trials of the Reward run suggested additional reactive
engagement of cognitive control, accompanied with transient activation in bilateral AI, lateral PFC, PPC, supplementary motor area, anterior cingulate cortex, putamen and caudate. Despite behavioural and neural differences during Baseline WM task performance, adolescents and adults showed similar
modulations of proactive and reactive control by reward
The patient perspective in the era of personalized medicine: What about scanxiety?
Frequency of scanning has accelerated in the era of personalized medicine and is related, but not restricted, to the exploding number of clinical trials for new cancer treatments. Particularly in drug trials, but also in clinical practice, patients are followed up by scans frequently, which may vary from every 6 to 12Ā weeks until progression. The authors aimed to raise awareness for this underreported but widely present "Sword of Damocles" scan-related issue also referred to as 'scanxiety.
Field-induced quantum critical route to a Fermi liquid in high-temperature superconductors
In high transition temperature (T_c) superconductivity, charge doping is a
natural tuning parameter that takes copper oxides from the antiferromagnet to
the superconducting region. In the metallic state above T_c the standard
Landau's Fermi-liquid theory of metals as typified by the temperature squared
(T^2) dependence of resistivity appears to break down. Whether the origin of
the non-Fermi-liquid behavior is related to physics specific to the cuprates is
a fundamental question still under debate. We uncover a new transformation from
the non-Fermi- to a standard Fermi-liquid state driven not by doping but by
magnetic field in the overdoped high-T_c superconductor Tl_2Ba_2CuO_{6+x}. From
the c-axis resistivity measured up to 45 T, we show that the Fermi-liquid
features appear above a sufficiently high field which decreases linearly with
temperature and lands at a quantum critical point near the superconductivity's
upper critical field -- with the Fermi-liquid coefficient of the T^2 dependence
showing a power-law diverging behavior on the approach to the critical point.
This field-induced quantum criticality bears a striking resemblance to that in
quasi-two dimensional heavy-Fermion superconductors, suggesting a common
underlying spin-related physics in these superconductors with strong electron
correlations.Comment: 6 pages, 4 figure
Prolonged exercise testing in two children with a mild Multiple Acyl-CoA-Dehydrogenase deficiency
BACKGROUND: Multiple Acyl-CoA-Dehydrogenase deficiency (MADD) is an inherited metabolic disorder characterized by impaired oxidation of fatty acids and some amino acids. METHODS: We were interested whether children with MADD could tolerate a prolonged low-intensity exercise test and if this test could have any additional diagnostic value. Therefore, we performed a maximal exercise test and a low-intensity prolonged exercise test in 2 patients with MADD and in 5 control subjects. During a prolonged exercise test the subjects exercised on a cycle ergometer at a constant workload of 30% of their maximum for 90 minutes and heart rate, oxygen uptake, fuel utilization and changes in relevant blood and urinary parameters were monitored. RESULTS: The tests were tolerated well. During the prolonged exercise test the fatty acid oxidation (FAO) was quite low compared to 5 control subjects, while characteristic metabolites of MADD appeared in plasma and urine. CONCLUSION: We suggest that the prolonged exercise test could be of diagnostic importance and might replace the fasting test as a diagnostic procedure in some cases, particularly in patients with anamnestic signs of intolerance for prolonged exercise
The role of illness scripts in the development of medical diagnostic expertise: Results from an interview study
In this article, we describe a study in which some current ideas about illness scripts are tested. Participants at 4 levels of medical expertise were asked to describe either a prototypical patient or the clinical picture associated with a number of different diseases. It was found that participants at intermediate levels of expertise mentioned, both absolutely and relatively, many enabling conditions (patient contextual factors such as sex, age, medical history, and occupation) when asked to describe a prototypical patient with a disease, whereas the instruction to describe the clinical picture of a disease revealed a monotonic relation with expertise level. The amount of biomedical information in the descriptions decreased with increasing expertise level for both types of instruction. In addition, a positive relation was found between number of actual patients seen with a particular disease and number of enabling conditions mentioned. These results were interpreted as supportive of the present conceptualization of the illness script theory
Sustained and transient processes in event-based prospective memory in adolescence and adulthood
Prospective memory (PM) refers to the cognitive processes associated with remembering to perform an intended action after a delay. Varying the salience of PM cues while keeping the intended response constant, we investigated the extent to which participants relied on strategic monitoring, through sustained, top-down, control, or on spontaneous retrieval via transient bottom-up processes. There is mixed evidence regarding developmental improvements in event-based PM performance after age 13. We compared PM performance and associated sustained and transient neural correlates in 28 typically developing adolescents (12-17 years) and 19 adults (23-30 years). Lower PM cue salience associated with slower ongoing task (OT) reaction times, reflected by increased Ī¼ Ex-Gaussian parameter, and sustained increases in frontoparietal activation during OT blocks, both thought to reflect greater proactive control supporting cue monitoring. Behavioural and neural correlates of PM trials were not specifically modulated by cue salience, revealing little difference in reactive control between conditions. The effect of cue salience was similar across age groups, suggesting that adolescents are able to adapt proactive control engagement to PM tasks demands. Exploratory analyses showed that younger, but not older, adolescents were less accurate and slower in PM trials relative to OT trials than adults and showed greater transient activation in PM trials in an occipito-temporal cluster. These results provide evidence of both mature and still maturing aspects of cognitive processes associated with implementation of an intention after a delay during early adolescence
Universal Behavior of Heavy-Fermion Metals Near a Quantum Critical Point
The behavior of the electronic system of heavy fermion metals is considered.
We show that there exist at least two main types of the behavior when the
system is nearby a quantum critical point which can be identified as the
fermion condensation quantum phase transition (FCQPT). We show that the first
type is represented by the behavior of a highly correlated Fermi-liquid, while
the second type is depicted by the behavior of a strongly correlated
Fermi-liquid. If the system approaches FCQPT from the disordered phase, it can
be viewed as a highly correlated Fermi-liquid which at low temperatures
exhibits the behavior of Landau Fermi liquid (LFL). At higher temperatures ,
it demonstrates the non-Fermi liquid (NFL) behavior which can be converted into
the LFL behavior by the application of magnetic fields . If the system has
undergone FCQPT, it can be considered as a strongly correlated Fermi-liquid
which demonstrates the NFL behavior even at low temperatures. It can be turned
into LFL by applying magnetic fields . We show that the effective mass
diverges at the very point that the N\'eel temperature goes to zero. The
phase diagrams of both liquids are studied. We demonstrate that these
phase diagrams have a strong impact on the main properties of heavy-fermion
metals such as the magnetoresistance, resistivity, specific heat,
magnetization, volume thermal expansion, etc.Comment: Revtex, 11 pages, revised and accepted by JETP Let
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