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Introduced species can have strong ecological, social and economic effects on their non-native environment. Introductions of megafaunal species are rare and may contribute to rewilding efforts, but they may also have pronounced socio-ecological effects because of their scale of influence. A recent introduction of the hippopotamus Hippopotamus amphibius into Colombia is a novel introduction of a megaherbivore onto a new continent, and raises questions about the future dynamics of the socio-ecological system into which it has been introduced. Here we synthesize current knowledge about the Colombian hippopotamus population, review the literature on the species to predict potential ecological and socio-economic effects of this introduction, and make recommendations for future study. Hippopotamuses can have high population growth rates (7–11%) and, on the current trajectory, we predict there could be 400–800 individuals in Colombia by 2050. The hippopotamus is an ecosystem engineer that can have profound effects on terrestrial and aquatic environments and could therefore affect the native biodiversity of the Magdalena River basin. Hippopotamuses are also aggressive and may pose a threat to the many inhabitants of the region who rely upon the Magdalena River for their livelihoods, although the species could provide economic benefits through tourism. Further research is needed to quantify the current and future size and distribution of this hippopotamus population and to predict the likely ecological, social and economic effects. This knowledge must be balanced with consideration of social and cultural concerns to develop appropriate management strategies for this novel introduction.
This study presents the first analysis of benthic megafauna and habitats from the Sabrina Coast shelf, encompassing a proposed Marine Protected Area. Sea bed imagery indicated an abundant benthic fauna compared to other parts of the Antarctic shelf, dominated by brittle stars, polychaete tubeworms, and a range of other sessile and mobile taxa. The distribution of taxa was related (ρ=0.592, P<0.001) to variations in water depth, latitude, substrate type and phytodetritus. High phytodetritus cover was associated with muddy/sandy sediments and abundant holothurians and amphipods, while harder substrates hosted abundant brachiopods, hard bryozoans, polychaete tubeworms, massive and encrusting sponges, and sea whips. Brittle stars, irregular urchins and anemones were ubiquitous. Variations in substrate largely reflected the distribution of dropstones, creating fine-scale habitat heterogeneity. Several taxa were found only on hard substrates, and their broad regional distribution indicated that the density of dropstones was sufficient for most sessile invertebrates to disperse across the region. The hexactinellid sponge Anoxycalyx joubini and branching hydrocorals exhibited a more restricted distribution, probably related to water depth and limited dispersal capability, respectively. Dropstones were associated with significant increases in taxa diversity, abundance and biological cover, enhancing the overall diversity and biomass of this ecosystem.
Decision-making is an essential component of executive function, and a critical skill of political leadership. Neuroanatomic localization studies have established the prefrontal cortex as the critical brain site for executive function. In addition to the prefrontal cortex, white matter tracts as well as subcortical brain structures are crucial for optimal executive function. Executive function shows a significant decline beginning at age 60, and this is associated with age-related atrophy of prefrontal cortex, cerebral white matter disease, and cerebral microbleeds. Notably, age-related decline in executive function appears to be a relatively selective cognitive deterioration, generally sparing language and memory function. While an individual may appear to be functioning normally with regard to relatively obvious cognitive functions such as language and memory, that same individual may lack the capacity to integrate these cognitive functions to achieve normal decision-making. From a historical perspective, global decline in cognitive function of political leaders has been alternatively described as a catastrophic event, a slowly progressive deterioration, or a relatively episodic phenomenon. Selective loss of executive function in political leaders is less appreciated, but increased utilization of highly sensitive brain imaging techniques will likely bring greater appreciation to this phenomenon. Former Israeli Prime Minister Ariel Sharon was an example of a political leader with a well-described neurodegenerative condition (cerebral amyloid angiopathy) that creates a neuropathological substrate for executive dysfunction. Based on the known neuroanatomical and neuropathological changes that occur with aging, we should probably assume that a significant proportion of political leaders over the age of 65 have impairment of executive function.
Individuals with generalized social anxiety disorder (gSAD) exhibit attentional bias to salient stimuli, which is reduced in patients whose symptoms improve after treatment, indicating that mechanisms of bias mediate treatment success. Therefore, pre-treatment activity in regions implicated in attentional control over socio-emotional signals (e.g. anterior cingulate cortex, dorsolateral prefrontal cortex) may predict response to cognitive behavioral therapy (CBT), evidence-based psychotherapy for gSAD.
During functional magnetic resonance imaging, 21 participants with gSAD viewed images comprising a trio of geometric shapes (circles, rectangles or triangles) alongside a trio of faces (angry, fearful or happy) within the same field of view. Attentional control was evaluated with the instruction to ‘match shapes’, directing attention away from faces, which was contrasted with ‘match faces’, whereby attention was directed to emotional faces.
Whole-brain voxel-wise analyses showed that symptom improvement was predicted by enhanced pre-treatment activity in the presence of emotional face distractors in the dorsal anterior cingulate cortex and dorsal medial prefrontal cortex. Additionally, CBT success was foretold by less activity in the amygdala and/or increased activity in the medial orbitofrontal gyrus during emotion processing.
CBT response was predicted by pre-treatment activity in prefrontal regions and the amygdala. The direction of activity suggests that individuals with intact attentional control in the presence of emotional distractors, regulatory capacity over emotional faces and/or less reactivity to such faces are more likely to benefit from CBT. Findings indicate that baseline neural activity in the context of attentional control and emotion processing may serve as a step towards delineating mechanisms by which CBT exerts its effects.
The Collaborative East Antarctic Marine Census (CEAMARC) surveys to the Terre Adélie and George V continental margin highlight the requirement for a revised high-resolution bathymetry model that can be used as a spatial tool for improving information on the physical environment of the region. We have combined shiptrack singlebeam and multibeam bathymetry, coastline data, and land and ice sheet topographic data to develop a new regional-scale bathymetry grid, called GVdem (short for George V digital elevation model). The GVdem grid spans an area between 138–148°E and 63–69°S, with a cell pixel size of 0.001-arcdegree (c. 100 m). The revised digital elevation model is a large improvement over previously available regional-scale grids from the area, and highlights seabed physiographic detail not formerly observed in this part of East Antarctica. In particular, the extent and complexity of the rugged inner-shelf valleys are revealed, and their spatial relationship with large shelf basins and adjacent flat-topped banks. The new grid also reveals further insight into the spatial distribution of the submarine canyons found on the continental slope.
Arid and semi-arid climates are mainly characterised as those areas where precipitation is less (and often considerably less) than potential evapotranspiration. These climate regions are ideal environments for salt to accumulate in natural soil and groundwater settings since evaporation and transpiration essentially remove freshwater from the system, leaving residual salts behind. Similarly, the characteristically low precipitation rates reduce the potential for salt to be diluted by rainfall. Thus arid and semi-arid regions make ideal ‘salt concentrator’ hydrologic environments. Indeed, salt flats, playas, sabkhas and saline lakes, for example, are ubiquitous features of arid and semi-arid regions throughout the world (Yechieli and Wood,2002). In such settings, variable density flow phenomena are expected to be important, especially where hypersaline brines overlie less dense groundwater at depth. In contrast, seawater intrusion in coastal aquifers is a global phenomenon that is not constrained to only arid and semi-arid regions of the globe and is inherently a variable density flow problem by its very nature. These two examples make it clear that variable density flow problems occur in, but importantly extend beyond, arid and semi-arid regions of the globe. The intention of this chapter is therefore not to limit ourselves to modelling arid zone hydrological systems, but rather to present a more general treatment of variable density groundwater flow and solute transport phenomena and modelling. The concepts presented in this chapter are therefore not climatologically constrained to arid or semi-arid zones of the world, although they do apply equally there.
Dense coral-sponge communities on the upper continental slope at 570–950 m off George V Land, East Antarctica have been identified as Vulnerable Marine Ecosystems. The challenge is now to understand their probable distribution on other parts of the Antarctic margin. We propose three main factors governing their distribution on the George V margin: 1) their depth in relation to iceberg scouring, 2) the flow of organic-rich bottom waters, and 3) their location at the head of shelf cutting canyons. Icebergs scour to 500 m in this region and the lack of such disturbance is a probable factor allowing the growth of rich benthic ecosystems. In addition, the richest communities are found in the heads of canyons which receive descending plumes of Antarctic Bottom Water formed on the George V shelf, which could entrain abundant food for the benthos. The canyons harbouring rich benthos are also those that cut the shelf break. Such canyons are known sites of high productivity in other areas due to strong current flow and increased mixing with shelf waters, and the abrupt, complex topography. These proposed mechanisms provide a framework for the identification of areas where there is a higher likelihood of encountering these Vulnerable Marine Ecosystems.
Garlic mustard is among the most important invasive weeds of North American eastern deciduous forests. Investigations of the mechanisms that enable its success as an invader require a simple method to propagate this weed in the laboratory and the greenhouse; we develop such a method in this study. Cold treatment (24-h dark cycle; maximum 6 C, minimum −1 C) for at least 100 d on a moist organic mix, followed by incubation at temperatures approximating spring (maximum 15 C, minimum 6 C), results in close to 100% germination. The information presented here will be valuable in studies requiring a steady supply of garlic mustard plants for experimentation and for the mass rearing of biological control agents.
Advances in the design of environmental reaction cells and in the collection of X-ray diffraction data are transforming our ability to study mineral-fluid interactions. The resulting increase in time resolution now allows for the determination of rate laws for mineral reactions that are coupled to atomic-scale changes in crystal structure. Here we address the extension of time-resolved synchrotron diffraction techniques to four areas of critical importance to the cycling of metals in soils: (1) cation exchange; (2) biomineralization; (3) stable isotope fractionation during redox reactions; and (4) nucleation and growth of nanoscale oxyhydroxides.
The relative incidence of childhood-onset bipolar illness in the USA compared with that in Europe is controversial. We examined this issue in more than 500 out-patients (average age 42 years) with bipolar illness who reported age at onset of first episode, family history, and childhood physical or sexual abuse. Childhood or adolescent onset of bipolar illness was reported by 61% of those in the US cohort but by only 30% of those in The Netherlands or Germany. In the USA there was also twice the incidence of childhood adversity and genetic/familial risk for affective disorder. The findings deserve replication and further exploration.
The SrFeO3/SiO2/Si thin film system has been studied using transmission electron microscopy (TEM). The thin films of SrFeO3 were grown by pulsed laser deposition onto silicon substrates with a SiO2 buffer layer at room temperature (RT) and 700 °C and subjected to annealing for various periods of time at temperature T = 700 °C. Transmission electron microscopy characterization showed that the microstructure of the film deposited at room temperature contained crystalline and amorphous layers. Silicon diffusion into SrFeO3 films occurred at the SiO2 interface for the samples deposited at 700 °C and for those films annealed at 700 °C. The silicon diffusion-induced interfacial reactions resulted in the phase transformations and the growth of complex crystalline and amorphous phases. The principal compositions of these phases were Sr(Fe,Si)12O19, SrOx and amorphous [Sr-Fe-O-Si].
Few studies have examined the relative risks of switching into hypomania
or mania associated with second-generation antidepressant drugs in
To examine the relative acute effects of bupropion, sertraline and
venlafaxine as adjuncts to mood stabilisers.
In a 10-week trial, participants receiving out-patient treatment for
bipolar disorder (stratified for rapid cycling) were randomly treated
with a flexible dose of one of the antidepressants, or their respective
matching placebos, as adjuncts to mood stabilisers.
A total of 174 adults with bipolar disorder I, II or not otherwise
specified, currently in the depressed phase, were included. All three
antidepressants were associated with a similar range of acute response
(49–53%) and remission (34–41%). There was a significantly increased risk
of switches into hypomania or mania in participants treated with
venlafaxine compared with bupropion or sertraline.
More caution appears indicated in the use of venlafaxine rather than
bupropion or sertraline in the adjunctive treatment of bipolar
depression, especially if there is a prior history of rapid cycling.
While severity of manic episodes can be successfully reduced, repeated recurrences are common with ~40% of patients meeting criteria for rapid cycling after aggressive treatment. Manic episodes present much earlier in children of bipolars and due to unique presentation physicians often mistakenly diagnose such children with attention-deficit/hyperactivity disorder. Differential symptoms include suicidal thoughts, grandiosity, hallucinations, and depressive withdrawal. Such children may require the usual combination treatment with a mood stabilizer and an antipsychotic, with the addition of a stimulant as well. Treatment of adults and children often includes second-generation antipsychotics, which have increasingly shown efficacy both as monotherapy and adjunctive treatments of acute mania. Most recently, some anticonvulsants have demonstrated acute antimanic properties as well and more studies of their role in bipolar disorder are underway.
Approximately 40% of bipolar patients experience rapid cycling, and half of these suffer from ultra-rapid or ultradian cycling. These patterns are also common in children. Rapid-cycling bipolar disorder is difficult to bring to remission and often requires treatment with four or more classes of psychotropic medications. Lithium, even in combination with anticonvulsants or antidepressants, is often associated with residual episodic depressions. Concerns with adjunctive antidepressant treatment include their low response and remission rates and their tendency to cause switch into mania. Atypical antipsychotics and selected agents within the anticonvulsant class are becoming increasingly important in the treatment of rapid cycling. In the absence of clear treatment guidelines, the use and sequencing of drugs in complex combination treatment remains exploratory, but should be individualized based on careful prospective mood charting by the patient. Use of several drugs below their side-effect thresholds may prevent certain side effects. In children, long-term safety considerations are particularly important in the absence of a strong controlled clinical trials database.
The Stanley Foundation Bipolar Network (SFBN) was created to address the paucity of help studies in bipolar illness.
To describe the rationale and methods of the SFBN.
The SFBN includes five core sites and a number of affiliated sites that have adopted consistent methodology for continuous longitudinal monitoring of patients. Open and controlled studies are performed as patients' symptomatology dictates.
The reliability of SFBN raters and the validity of the rating instruments have been established. More than 500 patients are in continuous daily longitudinal follow-up. More than 125 have been randomised to one of three of the newer antidepressants (bupropion, sertraline and venlafaxine) as adjuncts in a study of mood stabilisers and 93 to omega-3 fatty acids. A number of open clinical case series have been published.
Well-characterised patients are followed in a detailed continuous longitudinal fashion in both opportunistic case series and double-blind, randomised controlled trials with reliable and validated measures.