Local structural and metabolic as well as inter-regional connectivity abnormalities have been implicated in the neuropathology of major depressive disorder (MDD). How local tissue properties affect ...intrinsic functional connectivity is, however, unclear. Using a cross-sectional, multi-modal imaging approach, we investigated the relationship between local cortical tissue abnormalities and intrinsic resting-state functional connectivity (RSFC) in MDD.
A total of 20 MDD in-patients and 20 healthy controls underwent magnetic resonance imaging at 3 T for structural and functional imaging. Whole-brain cortical thickness was calculated and compared between groups. Regions with reduced cortical thickness defined seeds for subsequent whole-brain RSFC analyses. Contributions of structural tissue abnormalities on inter-regional RSFC were explicitly investigated.
Lower cortical thickness was observed in MDD in the right dorsomedial prefrontal cortex (PFC), superior temporal gyrus/temporal pole, middle-posterior cingulate cortex, and dorsolateral PFC. No differences in local fractional amplitude of low-frequency fluctuations were observed. Lower thickness in patients' dorsomedial PFC further directly and selectively affected its RSFC with the precuneus, which was unaffected by symptom severity. No effects of cortical thickness in other regions showing abnormal thickness were observed to influence functional connectivity.
Abnormal cortical thickness in the dorsomedial PFC in MDD patients was observed to selectively and directly affect its intrinsic connectivity with the precuneus in MDD patients independent of depression severity, thereby marking a potential vulnerability for maladaptive mood regulation. Future studies should include an unmedicated sample and replicate findings using independent component analysis to test for morphometric effects on network integrity.
The Carboniferous Zhibo and Chagangnuoer iron deposits are situated within a caldera centre and along the flank of the same volcanic edifice, respectively, in the Awulale Iron Metallogenic Belt of ...the Western Tianshan orogen. Several stratiform 10 to 100m large, tabular to lenticular shaped magnetite-dominated ore-bodies occur in (trachy-) andesitic to rhyolitic host rocks. The magnetite mineralization mainly occurs as massive iron ores, partly with columnar-network or flow textures, and as disseminated magnetite ores. Trace element and isotope investigations of the different ore types reveal two major groups of magnetite: Group I, represented by the massive, partly brecciated ores from both deposits, is enriched in Ti, V, Ni, and HFSE such as Y, with concentrations similar to Iron Oxide-Copper-Gold (IOCG) ores. The δ56Fe values (up to 0.4‰) support an ortho-magmatic origin corresponding with an isotopic source calculation at ~800°C. Positive correlations between Fetotal and δ56Fe (from +0.4‰ to −0.1‰) and incompatible trace element contents (e.g. Si, Al, Nb, Ti and Y) in Group I magnetite are interpreted to be the consequence of a Raleigh-type fractionation process. Decreasing V, Ni and Mn values indicate changing fO2 conditions at the time of ore genesis. Group II, which is represented by the disseminated ores from Chagangnuoer, is - compared to Group I - relatively depleted in elements like Ti, V, Ni and Y and further spans a dominant δ56Fe range from about 0‰ to −0.5‰. These textural and chemical characteristics and the garnet-actinolite-diopside-epidote-carbonate-K-feldspar paragenesis are in accordance with hydrothermal Fe-skarn ores.
The similar multi-element patterns of magnetite from all investigated samples, the overlapping δ56Fe ratios of the same massive ore-type from Zhibo and Chagangnuoer and the close proximity of both deposits indicate a common source of Fe-enrichment for the different iron ore types. In contrast to the ortho-magmatic Group I magnetite, reverse trace element trends with decreasing δ56Fe ratios (from 0‰ to −0.5‰) among the disseminated ores cannot simply be explained by a straightforward Raleigh fractionation or alteration processes. Therefore, a bimodal formation model is suggested for the Group II magnetite formation, including a partial remobilization of iron from the proximal, ortho-magmatic ore bodies and a subsequent distal re-precipitation. These processes were driven by late-stage hydrothermal fluids, which originated from deeper- seated granitic/granodioritic intrusions in the immediate vicinity.
•In-situ magnetite trace element and δ56Fe studies of volcanic-hosted massive iron ore•Trace element trends of ortho-magmatic magnetite reveal Raleigh-type fractionation.•Hydrothermal processes responsible for magnetite remobilization and re-precipitation
•Demographic feature young age is a potential clozapine response predictor.•Clinical factors few negative symptoms and schizophrenia paranoid subtype are potential predictors.•Large clinical trials ...should be done to find response predictors.
Clozapine (CLZ) is prescribed to (relatively) treatment-resistant patients with schizophrenia spectrum disorders. Currently, it is unknown what factors predict response to CLZ. Therefore, we performed meta-analyses to identify predictors of CLZ response, hence aiming to facilitate timely and efficient prescribing of CLZ.
A systematic search was performed in ‘Pubmed’ and ‘Embase’ until 1 January 2019. Articles were eligible if they provided data on predictors of CLZ response measured demographic and clinical factors at baseline or biochemical factors at follow-up in schizophrenia spectrum disorder patients.
A total of 34 articles, total number of participants = 9386; N unique = 2094, were eligible. Factors significantly associated with better CLZ response were: lower age, lower PANSS negative score and paranoid schizophrenia subtype.
The results of our meta-analyses suggest that three baseline demographic and clinical features are associated with better clozapine response, i.e. relatively young age, few negative symptoms and paranoid schizophrenia subtype. These variables may be taken into account by clinicians who consider treating a specific patient with CLZ.
Glutamatergic mechanisms and resting-state functional connectivity alterations have been recently described as factors contributing to major depressive disorder (MDD). Furthermore, the pregenual ...anterior cingulate cortex (pgACC) seems to play an important role for major depressive symptoms such as anhedonia and impaired emotion processing. We investigated 22 MDD patients and 22 healthy subjects using a combined magnetic resonance spectroscopy (MRS) and resting-state functional magnetic resonance imaging (fMRI) approach. Severity of depression was rated using the 21-item Hamilton depression scale (HAMD) and patients were divided into severely and mildly depressed subgroups according to HAMD scores. Because of their hypothesized role in depression we investigated the functional connectivity between pgACC and left anterior insular cortex (AI). The sum of Glutamate and Glutamine (Glx) in the pgACC, but not in left AI, predicted the resting-state functional connectivity between the two regions exclusively in depressed patients. Furthermore, functional connectivity between these regions was significantly altered in the subgroup of severely depressed patients (HAMD > 15) compared to healthy subjects and mildly depressed patients. Similarly the Glx ratios, relative to Creatine, in the pgACC were lowest in severely depressed patients. These findings support the involvement of glutamatergic mechanisms in severe MDD which are related to the functional connectivity between pgACC and AI and depression severity.
Endocrinopathic causes of laminitis may be a common underlying causative pathogenesis in first-opinion or field cases presenting with laminitis, as opposed to laminitis produced in inflammatory ...research models. This study aimed to determine whether evidence of an underlying endocrinopathy was present in horses presented for laminitis to a first-opinion/referral veterinary teaching hospital. A second aim was to compare the signalment of horses and ponies with laminitis with the equine hospital population during the same period. All horses presenting for laminitis at Helsinki University Equine Teaching Hospital, Finland, over a 16-month period were examined for an underlying endocrinopathy. Horses presenting for laminitis were compared with the hospitalized population over the same period. There were 36 horses presented for laminitis, and evidence of endocrinopathy was present in 89%. Of the horses showing an underlying endocrinopathy, one-third had a diagnosis of pituitary pars intermedia dysfunction, and two-thirds showed basal hyperinsulinemia indicative of insulin resistance, without evidence of hirsutism. Phenotypic indicators of obesity were present in 95% of horses with basal hyperinsulinemia without hirsutism. Compared with the hospital population during the same period, horses with laminitis associated with an underlying endocrinopathy were significantly older and more likely to be pony breeds. Our data support that endocrine testing should be performed on all cases of laminitis that do not have a clear inflammatory or gastrointestinal origin.
The enhanced abilities of online retailers to learn about their customers' shopping behaviors have increased fears of dynamic pricing, a practice in which a seller sets prices based on the estimated ...buyer's willingness-to-pay. However, among online retailers, a deviation from a one-price-for-all policy is the exception. When price discrimination is observed, it is often in the context of customer outrage about unfair pricing. One setting where pricing varies is the name-your-own-price (NYOP) mechanism. In contrast to a typical retail setting, in NYOP markets, it is the buyer who places an initial offer. This offer is accepted if it is above some threshold price set by the seller. If the initial offer is rejected, the buyer can update her offer in subsequent rounds. By design, the final purchase price is opaque to the public; the price paid depends on the individual buyer's willingness-to-pay and offer strategy. Further, most forms of NYOP employ a fixed threshold price policy. In this paper, we compare a fixed threshold price setting with an adaptive threshold price setting. A seller who considers an adaptive threshold price has to weigh potentially greater profits against customer objections about the perceived fairness of such a policy. We first derive the optimal strategy for the seller. We analyze the effectiveness of an adaptive threshold price vis-à-vis a fixed threshold price on seller profit and customer satisfaction. Further, we evaluate the moderating effect of revealing the threshold price policy (adaptive versus fixed) to buyers. We test our model in a series of laboratory experiments and in a large field experiment at a prominent NYOP seller involving real purchases. Our results show that revealing the usage of an adaptive mechanism yields higher profits and more transactions than not revealing this information. In the field experiment, we find that applying a revealed adaptive threshold price can increase profits by over 20 percent without lowering customer satisfaction.
A number of studies have shown that the boron isotopic composition (δ11B) and the B / Ca ratio of biogenic carbonates (mostly foraminifers) can serve as proxies for two parameters of the ocean's ...carbonate chemistry, rendering it possible to calculate the entire carbonate system. However, the B incorporation mechanism into marine carbonates is still not fully understood and analyses of field samples show species-specific and hydrographic effects on the B proxies complicating their application. Identifying the carbonate system parameter influencing boron incorporation is difficult due to the co-variation of pH, CO32- and B(OH)4-. To shed light on the question which parameter of the carbonate system is related to the boron incorporation, we performed culture experiments with the benthic symbiont-bearing foraminifer Amphistegina lessonii using a decoupled pH–CO32- chemistry. The determination of the δ11B and B / Ca ratios was performed simultaneously by means of a new in situ technique combining optical emission spectroscopy and laser ablation MC-ICP-MS. The boron isotopic composition in the tests gets heavier with increasing pH and B / Ca increases with increasing B(OH)4- / HCO3- of the culture media. The latter indicates that boron uptake of A. lessonii features a competition between B(OH)4- and HCO3-. Furthermore, the simultaneous determination of B / Ca and δ11B on single specimens allows for assessing the relative variability of these parameters. Among different treatments the B / Ca shows an increasing variability with increasing boron concentration in the test whereas the variability in the isotope distribution is constant.
Laser-ablation ICPMS has become widely accessible as a powerful and efficient multi-element microanalytical technique. One of its key strengths is the ability to analyse a wide concentration range ...from major (tens of wt.%) to trace (ng/g) levels in minerals and their microscopic inclusions. An ArF excimer laser system (λ = 193 nm) with imaging optics for controlled UV ablation and simultaneous petrographic viewing was designed specifically for representative sampling and quantitative multi-element analysis of microscopic fluid, melt and mineral inclusions beneath the sample surface. After a review of the requirements and recent technical developments, results are presented which together document the reliability and reproducibility of quantitative microanalysis of complex samples such as zoned crystals or fluid and melt inclusions in various host minerals. Analytical errors due to elemental fractionation are reduced to the typical precision achieved by quadrupole LA-ICPMS in multi-element mode (2–5% RSD). This progress is largely due to the small size of aerosol particles generated by the optimized UV optical system. Depth profiling yields representative and accurate concentration results at a resolution of ∼0.1 μm perpendicular to the ablation surface. Ablation is largely matrix-insensitive for different elements, such that silicate and borate glasses, silicates and oxide minerals, or direct liquid ablation can be used interchangeably for external standardization of any homogeneous or heterogeneous material. The absolute ablation rate is material dependent, however, so that quantitative LA-ICPMS analysis requires an internal standard (i.e., an independent constraint such as the absolute concentration of one element).
Our approach to quantifying fluid and melt inclusion compositions is described in detail. Experiments with synthetic fluid inclusions show that accurate results are obtained by combining the LA-ICPMS analysis of element concentration ratios with a microthermometric measurement of the NaCl equivalent concentration and an empirical description of the effect of major cations on the final melting temperatures of ice, hydrohalite or halite. Expected calibration errors for NaCl-H
2O-dominated fluids are smaller than the typical analytical scatter within an assemblage of simultaneously trapped fluid inclusions. Analytical precision is limited by representative ablation of all phases in heterogeneous inclusions and the integration of transient ICPMS signals, to typically ±10 to 20% RSD. Element concentrations in devitrified and even coarsely crystallized silicate melt inclusions can be reconstituted from LA-ICPMS signals. Deconvolution of inclusion and host signals with internal standardization automatically corrects for sidewall crystallization after melt entrapment at high temperature. A test using melt inclusions in a midocean ridge basalt, a summary of published geochemical studies and a new application to REE analysis of coexisting fluids and mineral phases in carbonatite-related veins illustrate the versatility and some of the strengths and limitations of LA-ICPMS, in comparison with other microanalytical techniques.
Coral reefs occupy only ~ 0.1 percent of the ocean's habitat, but are the most biologically diverse marine ecosystem. In recent decades, coral reefs have experienced a significant global decline due ...to a variety of causes, one of the major causes being widespread coral bleaching events. During bleaching, the coral expels its symbiotic algae, thereby losing its main source of nutrition generally obtained through photosynthesis. While recent coral bleaching events have been extensively investigated, there is no scientific data on historical coral bleaching prior to 1979. In this study, we employ high-resolution femtosecond Laser Ablation Multiple Collector Inductively Coupled Plasma Mass Spectrometry (LA-MC-ICP-MS) to demonstrate a distinct biologically induced decline of boron (B) isotopic composition (δ11B) as a result of coral bleaching. These findings and methodology offer a new use for a previously developed isotopic proxy to reconstruct paleo-coral bleaching events. Based on a literature review of published δ11B data and our recorded vital effect of coral bleaching on the δ11B signal, we also describe at least two possible coral bleaching events since the Last Glacial Maximum. The implementation of this bleaching proxy holds the potential of identifying occurrences of coral bleaching throughout the geological record. A deeper temporal view of coral bleaching will enable scientists to determine if it occurred in the past during times of environmental change and what outcome it may have had on coral population structure. Understanding the frequency of bleaching events is also critical for determining the relationship between natural and anthropogenic causes of these events.
PDF
