Previous Set Of Experiments Research Articles

An experimental approach to training mood for resilience.

According to influential theories about mood, exposure to environments characterized by specific patterns of punishments and rewards could shape mood response to future stimuli. This raises the intriguing possibility that mood could be trained by exposure to controlled environments. The aim of the present study is to investigate experimental settings that increase resilience of mood to negative stimuli. For this study, a new task was developed where participants register their mood when rewards are added or subtracted from their score. The study was conducted online, using Amazon MTurk, and a total of N = 1287 participants were recruited for all three sets of experiments. In an exploratory experiment, sixteen different experimental task environments which are characterized by different mood-reward relationships, were tested. We identified six task environments that produce the greatest improvements in mood resilience to negative stimuli, as measured by decreased sensitivity to loss. In a next step, we isolated the two most effective task environments, from the previous set of experiments, and we replicated our results and tested mood's resilience to negative stimuli over time, in a novel sample. We found that the effects of the task environments on mood are detectable and remain significant after multiple task rounds (approximately two minutes) for an environment where good mood yielded maximum reward. These findings are a first step in our effort to better understand the mechanisms behind mood training and its potential clinical utility.

A possible neurophysiological correlate of audiovisual binding and unbinding in speech perception.

Audiovisual (AV) speech integration of auditory and visual streams generally ends up in a fusion into a single percept. One classical example is the McGurk effect in which incongruent auditory and visual speech signals may lead to a fused percept different from either visual or auditory inputs. In a previous set of experiments, we showed that if a McGurk stimulus is preceded by an incongruent AV context (composed of incongruent auditory and visual speech materials) the amount of McGurk fusion is largely decreased. We interpreted this result in the framework of a two-stage “binding and fusion” model of AV speech perception, with an early AV binding stage controlling the fusion/decision process and likely to produce “unbinding” with less fusion if the context is incoherent. In order to provide further electrophysiological evidence for this binding/unbinding stage, early auditory evoked N1/P2 responses were here compared during auditory, congruent and incongruent AV speech perception, according to either prior coherent or incoherent AV contexts. Following the coherent context, in line with previous electroencephalographic/magnetoencephalographic studies, visual information in the congruent AV condition was found to modify auditory evoked potentials, with a latency decrease of P2 responses compared to the auditory condition. Importantly, both P2 amplitude and latency in the congruent AV condition increased from the coherent to the incoherent context. Although potential contamination by visual responses from the visual cortex cannot be discarded, our results might provide a possible neurophysiological correlate of early binding/unbinding process applied on AV interactions.

Pattern scaling: Its strengths and limitations, and an update on the latest model simulations

We review the ideas behind the pattern scaling technique, and focus on its value and limitations given its use for impact assessment and within integrated assessment models. We present estimates of patterns for temperature and precipitation change from the latest transient simulations available from the Coupled Model Inter-comparison Project Phase 5 (CMIP5), focusing on multi-model mean patterns, and characterizing the sources of variability of these patterns across models and scenarios. The patterns are compared to those obtained from the previous set of experiments, under CMIP3. We estimate the significance of the emerging differences between CMIP3 and CMIP5 results through a bootstrap exercise, while also taking into account the fundamental differences in scenario and model ensemble composition. All in all, the robustness of the geographical features in patterns of temperature and precipitation, when computed as multi-model means, is confirmed by this comparison. The intensity of the change (in both the warmer and cooler areas with respect to global temperature change, and the drier and wetter regions) is overall heightened per degree of global warming in the ensemble mean of the new simulations. The presence of stabilized scenarios in the new set of simulations allows investigation of the performance of the technique once the system has gotten close to equilibrium. Overall, the well established validity of the technique in approximating the forced signal of change under increasing concentrations of greenhouse gases is confirmed.

Probing the O2 (aΔg1) photofragment following ozone dissociation within the long wavelength tail of the Hartley band

The technique of resonance enhanced multiphoton ionization (REMPI) has been used in conjunction with time-of-flight mass spectrometry (TOFMS), to investigate the dynamics of ozone photolysis in the long wavelength region of the Hartley band (301-311 nm). Specifically, both the translational anisotropy and the rotational angular momentum orientation of the O(2) (a (1)Delta(g); nu=0, J=16-20) fragments have been measured as a function of photolysis wavelength. Within this region, the thermodynamic thresholds for the formation of these products in combination with O ((1)D(2)) are approached and passed, and consequently these studies have allowed an investigation into the effects on the dynamics of slowing fragment recoil velocities and the increasing importance of vibrationally mediated photolysis. The determined beta parameters for all the J states probed follow a similar trend, decreasing from a value typical for the initial (1)B(2)<--(1)A(1) excitation responsible for the Hartley band [for example, beta=1.40+/-0.12 for the O(2) (a (1)Delta(g); J=18) fragment], to a much lower value beyond the thermodynamic threshold for the fragment's production (for example, beta=0.63+/-0.19 for the J=18 fragment following photolysis at 311 nm). This trend, similar to that observed when probing the atomic fragment in a previous set of experiments, [Horrocks et al., J. Chem. Phys. 125, 133313 (2006); Denzer et al., Phys. Chem. Chem. Phys. 16, 1954 (2006)] is consistent with the photodissociation of vibrationally excited ozone molecules beyond the threshold wavelengths and we estimate approximately 1/3 of this to be from excitation in the nu(3) asymmetric stretching mode. These observations are substantiated by the values of the beta(0) (2)(2,1) orientation moment measured, which for photolysis at 301 nm are negative, indicating that a bond opening mechanism provides the key torque for the departing O(2) fragment. The orientation moment becomes positive again for photolysis beyond threshold, however, as the increasing impulsive dissociation again begins to dominate the nature of the rotation of the departing molecular fragment. In addition, a (2+2) REMPI scheme has been utilized to probe the O(2) (a (1)Delta(g)) "low" J fragments, where the majority of the population resides following photolysis within this region. The REMPI-TOFMS technique has been used to confirm the rotational character of a spectral feature through examination of the signal line shapes obtained using different experimental geometries. The dynamical information subsequently obtained, probing the "low" J O(2) (a (1)Delta(g)) fragments on these rotational transitions, has unified previous translational anisotropy results obtained by detecting the O ((1)D(2)) atomic fragment with data for the O(2) (a (1)Delta(g); J=16-20) fragments.

Laboratory evaluation of the hypoglycemic effect of Anacardium occidentale Linn (Anacardiaceae) stem-bark extracts in rats.

This study evaluated the hypoglycemic effect of stem-bark extracts of Anacardium occidentale Linn., of the Anacardiaceae family, in normal (normoglycemic) and in streptozotocin-treated diabetic rats. Young adult, male Wistar rats weighing 250-300 g were used. Diabetes mellitus was induced in the test rats by intraperitoneal injections of streptozotocin (STZ, 90 mg/kg). In one set of experiments, graded doses of the aqueous and methanolic stem-bark extracts of A. occidentale (100-800 mg/kg p.o.) were separately administered to groups of fasted normal and fasted diabetic rats. In another set of experiments, 800 mg/kg p.o. of the aqueous or methanolic extract of the plant, a dose which produced maximal hypoglycemic effects in both fasted normal and diabetic rats in the previous set of experiments, were used. The hypoglycemic effects of single doses (i.e., 800 mg/kg p.o.) of A. occidentale stem-bark aqueous and methanolic extracts were compared with those of insulin (5 microU/kg s.c.) and glibenclamide (0.2 mg/kg p.o.) in both fasted normal and fasted diabetic rats. Following acute treatment, relatively moderate-to-high doses of A. occidentale stem-bark extracts (100-800 mg/kg p.o.) produced dose-dependent, significant reductions (p< 0.05-0.001) in the blood glucose concentrations of both fasted normal and fasted diabetic rats. On their own, both insulin (5 microU/kg s.c.) and glibenclamide (0.2 mg/kg p.o.) produced significant reductions (p< 0.01-0.001) in the blood glucose concentrations of the fasted normal and fasted diabetic rats. At single doses of 800 mg/kg p.o., A. occidentale stem-bark aqueous and methanolic extracts significantly reduced (p< 0.001) the mean basal blood glucose concentrations of fasted normal and fasted diabetic rats. The hypoglycemic effect of the methanolic plant extract was found to be slightly more pronounced than that of the aqueous plant extract in both the normal and diabetic rats examined. A. occidentale contains a diverse group of chemical compounds. Since methanol extractives of plants usually contain many chemical compounds, each of which is capable of producing definite biological activities via different mechanisms, it is difficult to draw any logical conclusion on the mechanism of the hypoglycemic effect of such a diverse mixture of chemical compounds contained in the plant extracts used in this study. While it is possible that the hypoglycemic effects of the plant extracts may be due, at least in part, to their terpenoid and/or coumarin contents, the mechanism of their hypoglycemic action remains largely speculative. However, this is unlikely to be due to the stimulation of pancreatic beta-cells and subsequent secretion of insulin. Although A. occidentale stem-bark aqueous or methanolic extract is less potent than insulin as an antidiabetic agent, the results of this experimental animal study indicate that it possesses hypoglycemic activity, and thus lends credence to the folkloric use of the plant in the management and/or control of adult-onset, type-2 diabetes mellitus among the Yoruba-speaking people of Western Nigeria.

Hypoglycaemic effect of Clausena anisata (Willd) Hook methanolic root extract in rats

This study was designed to examine the hypoglycaemic effect of Clausena anisata (Willd) Hook [family: Rutaceae] root methanolic extract in normal (normoglycaemic) and in streptozotocin-treated diabetic rats. Young adult, male Wistar rats (Rattus norvegicus) weighing 250–300 g were used. Diabetes mellitus was induced in the group of diabetic ‘test’ rats by intraperitoneal injections of streptozotocin (STZ, 90 mg/kg). In one set of experiments, graded doses of the methanolic root extract of C. anisata (CAME, 100–800 mg/kg p.o.) were administered to both fasted normal and fasted diabetic rats. In another set of experiments, 800 mg/kg of CAME, a dose of the plant extract which produced maximal hypoglycaemic effect in both fasted normal and diabetic rats in the previous set of experiments, was used. The hypoglycaemic effect of this single dose of C. anisata root methanolic extract (i.e. CAME, 800 mg/kg p.o.) was compared with those of insulin (5 μU/kg s.c.) and glibenclamide (0.2 mg/kg p.o.) in both fasted normal and fasted diabetic rats. Following acute treatment, relatively moderate to high doses of CAME (100–800 mg/kg p.o.) produced dose-dependent, significant reductions (P<0.05–0.001) in the blood glucose concentrations of both fasted normal and fasted diabetic rats. On their own, both insulin (5 μU/kg s.c.) and glibenclamide (0.2 mg/kg p.o.) produced significant reductions (P<0.01–0.001) in the blood glucose concentrations of the fasted normal and diabetic rats. At a dose of 800 mg/kg p.o., CAME reduced the mean basal blood glucose concentrations of fasted normal and fasted diabetic rats by 57.52 and 51.30%, respectively. C. anisata contains a diverse group of chemical compounds (see Table 1Table 1Known chemical constituents and medicinal uses of C. anisata (Willd) Hook [family: Rutaceae]Chemical constituentsMedicinal usesDifferent chemical compounds have been isolated from the various morphological parts of the plant (Hutchings et al., 1996), including many terpenoid hydrocarbons, sesquiterpenoids and fatty acids; and methychavicol, myrcene, umbelliferone, scopoletin, xanthotoxin, pimpenellin, xanthotoxol, bergapten; the alkaloids clausanitine and mupamine; as well as more than 20 coumarins, including chalepin, osthole, coumarrayin, xanthoxyletin, heliettin, imperatorin; and limonoids, including limonin and limonene; zapoteterin, clausenolide and clausenarin; capnolatone, triphasiol, and 4 aniosocoumarins; volatile oil containing phenylpropanoids and an acute toxic principle, estragole; furanocoumarin lactones, including indicolactonediol, anisolactone and 2′,3′-epoxyanisolactone.The various morphological parts of this plant have been reported (Hutchings et al., 1996) to be useful as effective remedies against parasitic infections, especially flatworm infestations, such as taeniasis and schistosomiasis; as well as in eye complaints; influenza and other respiratory ailments; heart disorders and hypertension; abdominal cramps, constipation and gastro-enteritis; hepatic diseases causing bad breath; malaria, fevers and pyrexia; boils, rheumatism, arthritis, and other inflammatory conditions; headaches, body pains, toothaches and swollen gums; convulsions and some other mental disorders; impotence and sterility; blood tonic; dysentery in cattle.). Since methanol extractives of plants are usually known to contain many chemical compounds, each of which is capable of producing definite biological activities via different mechanisms, it is difficult to draw any logical conclusion on the mechanism of the hypoglycaemic effect of such a diverse mixture of chemical compounds contained in the plant extract used in this study. While it is possible that the hypoglycaemic effect of the plant extract may be due, at least in part, to its terpenoid and coumarin contents, the mechanism of its hypoglycaemic action remains largely speculative, and is unlikely to be due to the stimulation of pancreatic β-cells and subsequent secretion of insulin. Although C. anisata root methanolic extract is less potent than insulin as an antidiabetic agent, the results of this experimental animal study indicate that the herb possesses hypoglycaemic activity; and thus lend credence to the suggested folkloric use of C. anisata root in the management and/or control of adult-onset, Type-2 diabetes mellitus in some communities of South Africa.

The Role of a Massive Central Singularity in Galactic Mergers on the Survival of the Core Fundamental Plane

In order for the core Fundamental Plane (cFP) to endure, small ellipticals must not survive mergers with giant ellipticals, despite the fact the small secondary galaxy can be as much as a million times more dense than the primary. However, our previous set of experiments has shown that, for purely stellar galaxies, the secondary does in fact survive mergers with primaries up to 100 times more massive. In this paper, we demonstrate the effect that a massive central black hole has on mergers of cFP galaxies. Our results indicate that the addition of a massive central singularity inside the primary galaxy provides strong enough tidal forces to destroy dense cFP companions when the secondary's orbital decay is sufficiently elongated. The destruction of the secondary acts to preserve the original low central density profile of the primary in the giant merger remnant, which allows the remnant to remain on the cFP. On more circular orbits, though, the secondary is only disrupted near the end of the merger, and the degree to which the secondary particles disperse depends on the amount of orbital energy left in the merger. Hence, there are some mergers for which the cFP is not preserved in our experiments. We find that if the secondary is not dispersed, it forms a spinning stellar disk with a central density that forces the merger remnant off the cFP.

Axonal growth on astrocytes is not inhibited by oligodendrocytes.

Axon growth in vitro may be inhibited by contact with oligodendrocytes, but most axons grow readily on the surface of astrocyte monolayers. Since both cell types are in close contact with one another in the damaged nervous system, we have examined the growth of axons on cultures which contain both astrocytes and oligodendrocytes. Cultures derived from neonatal rat forebrain develop with a monolayer of large flat astrocytes attached to the culture dish, and with many smaller cells of the oligodendrocyte lineage on their surface. Dorsal root ganglia placed on these cultures grow axons readily, the overall extent of growth being unaffected by the presence or absence of oligodendrocytes, many of which express galactocerebroside and the inhibitory molecule janusin. A previous set of experiments had shown that growth of these axons is inhibited by oligodendrocytes by themselves. Scanning electron microscopy coupled with silver-intensified immunostaining reveals that the axons grow on the surface of the astrocytic layer, underneath the oligodendrocytes, and are therefore in contact with both cell types as they grow. The presence of astrocytes therefore alters the results of axonal contact with oligodendrocytes.

An 80-bp cis-acting regulatory region controls cAMP and development regulation of a prestalk gene in Dictyostelium.

We have analyzed an 80-bp region containing the cis-acting sequences necessary for regulation of the Dictyostelium discoideum prestalk gene pst-cathepsin at the appropriate stage during multicellular development and in response to cAMP in single-cell culture. The region lies between approximately -280 and -200 bp upstream from the Cap site and contains two intertwined G/C-rich sequences, including a palindromic sequence and a direct repeat of the 3' portion of the palindrome. In a previous set of experiments, we showed that the direct repeat, or G-box, is important in the regulation of pst-cath expression. In this paper, we use a series of nested internal deletions to define other regions within the promoter required for cAMP and developmental expression, to further examine the importance of the two G-boxes, and to examine the functional relationship of the G-boxes with respect to the other regulatory sequences. Analysis of the expression of these constructs in transformed cells showed that both the 5' portion of the palindrome and the two G-boxes are required for promoter function and are capable of developmentally regulating pst-cath expression. An A/T-rich sequence located 5' to the G/C-rich sequence is also essential for maximal expression, whereas insertion of a linker 5' to this region suggests the presence of a negative element functional during multicellular development. The spacing between the G-box sequences proved to be important for the full induction of gene expression. Constructs containing the G-boxes at wild-type spacing or closer show wild-type or near wild-type levels of expression, whereas expansion of the region between the G-boxes leads to a substantial drop in the level of gene expression in response to cAMP. Insertion of an oligonucleotide containing one of the G-boxes and surrounding sequences can partially complement deletions in which this region has been removed. Analysis of the expression of the cassette constructs, in some cases, revealed significant differences in the quantitative level of expression under the two developmental conditions. This suggests that there are either qualitative or quantitative differences in the factors controlling the expression of this gene under these two conditions.

Variations in Motility Associated with Striatal Acetylcholine Levels

In the course of investigations of interstriatal relationships, studied with electrical stimulation, small unilateral lesions were placed into the dorsomedial reticular formation of rats at the superior collicular level. Following the placement of these lesions, the amplitudes of the summed and averaged interstriatal responses were greatly increased. A clinical correlate was reduction of the speed of locomotion, at times advancing to complete akinesia, catatonia, and frequently generalized clonus. The acetylcholine (Ach) level (as determined in five control animals) rose from the mean striatal level of 6.5 &lt;i&gt;µ&lt;/i&gt;g/g (±1.02) by 100% to 13.3 &lt;i&gt;µ&lt;/i&gt;g/g (±1.16) 6–8 h after the reticular lesion was placed. The Ach level was determined according to the method of Crossland after the animals were killed in liquid nitrogen. We then placed in a series of other rats large lesions into the amygdaloid complex, including the origin of the stria terminalis. Catalepsy did not occur when this procedure was followed by injury to the midbrain tegmentum. These rats showed spontaneous locomotion, and clonic seizures appeared only infrequently. In these animals, the mean amount of Ach in the striata was only slightly elevated to 7.1 &lt;i&gt;µ&lt;/i&gt;g/g (±0.76). The elevation of Ach in the striate, produced in the previous set of experiments by lesions in the reticular formations, was prevented by the prior placement of amygdaloid lesions. In addition, the amygdaloid lesion prevented an increase of amplitude of the interstriatally evoked and recorded responses. Symmetrel (amantadine hydrochloride) is known to enhance dopamine turnover in the striata of untreated rats. It also increases spontaneous running speed during the initial dosages. Thereafter, repeated daily administration of large doses of Symmetrel was followed by decreased locomotion and eventually bradykinesia or akinesia with rigidity. In these rats, the striatal Ach level increased to 10.7 &lt;i&gt;µ&lt;/i&gt;g/g (± 0.92). Since the above mentioned experimental catatonia developed as a consequence of striatal excitation associated with Ach increase, we followed this line of experiments in another group of rats with subcutaneous injections of small amounts of bulbocapnine measuring 11.5 &lt;i&gt;µ&lt;/i&gt;g/g (±0.91). This finding raised the possibility that the catatonia produced by bulbocapnine is the consequence of an elevation in the striatal levels of Ach and accompanying physiological events in the striatal system. The catatonia produced by the various manipulations described could be reversed by the injection of 80–100 mg &lt;i&gt;L&lt;/i&gt;-dopa in solution, i.p. and sometimes locomotor activity was even greater than that observed in the control period.