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1.
Int J Cardiol ; 314: 13-19, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32353492

RESUMO

BACKGROUND: Quantitative flow ratio (QFR) is a novel, adenosine-free method for functional lesion interrogation based on 3-dimensional quantitative coronary angiography and computational algorithms. We sought to investigate the diagnostic performance of QFR versus myocardial perfusion imaging positron emission tomography (MPI-PET), which yields the highest accuracy for detection of myocardial ischemia. METHODS: Diagnostic performance of QFR versus MPI-PET was assessed in consecutive patients undergoing both clinically indicated coronary angiography and 13N-ammonia MPI-PET within a six-month period. RESULTS: Out of 176 patients (439 coronary arteries), 19.3% were women. Percent area stenosis was 45 [32-58] %. Myocardial ischemia on 13N-ammonia MPI-PET was detected in 106 (24.1%) vessel territories and hemodynamic significance defined as contrast-flow vessel QFR ≤ 0.80 was observed in 83 (18.9%) vessels. Diagnostic accuracy, sensitivity, and specificity of contrast-flow vessel QFR for the prediction of myocardial ischemia on 13N-ammonia MPI-PET were 92.5 (95% CI 89.6-94.7) %, 73.6 (95% CI 64.1-81.7) %, and 98.5 (95% CI 96.5-99.5) %, respectively. The AUCs for contrast-flow vessel QFR, percent diameter stenosis, and percent area stenosis were 0.85 (95% CI 0.81-0.88, p < 0.001), 0.76 (95% CI 0.71-0.79, p < 0.001) and 0.75 (95% CI 0.70-0.79, p < 0.001), respectively. CONCLUSIONS: QFR, a novel diagnostic tool for functional coronary lesion assessment, provides good diagnostic agreement with MPI-PET and superior diagnostic accuracy for the detection of myocardial ischemia as compared to anatomic indices. Future studies will have to determine the non-inferiority of QFR to fractional flow reserve with respect to clinical outcomes.

2.
Artigo em Inglês | MEDLINE | ID: mdl-32285987

RESUMO

Lanthanide permanent magnets are widely used in applications ranging from nanotechnology to industrial engineering. However, limited access to the rare earths and rising costs associated with their extraction are spurring interest in the development of lanthanide-free hard magnets. Zero- and one-dimensional magnetic materials are intriguing alternatives due to their low densities, structural and chemical versatility, and the typically mild, bottom-up nature of their synthesis. Here, we present two one-dimensional cobalt(II) systems Co(hfac)2 (R-NapNIT) (R-NapNIT=2-(2'-(R-)naphthyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, R=MeO or EtO) supported by air-stable nitronyl nitroxide radicals. These compounds are single-chain magnets and exhibit wide, square magnetic hysteresis below 14 K, with giant coercive fields up to 65 or 102 kOe measured using static or pulsed high magnetic fields, respectively. Magnetic, spectroscopic, and computational studies suggest that the record coercivities derive not from three-dimensional ordering but from the interaction of adjacent chains that compose alternating magnetic sublattices generated by crystallographic symmetry.

3.
J Anim Ecol ; 89(6): 1329-1339, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32144759

RESUMO

Restricting movements to familiar areas should increase individual fitness as it provides animals with information about the spatial distribution of resources and predation risk. While the benefits of familiarity for locating resources have been reported previously, the potential value of familiarity for predation avoidance has been accorded less attention. It has been suggested that familiarity should be beneficial for anti-predator behaviour when direct cues of predation risk are unclear and do not allow prey to identify well-defined spatial refuges. However, to our knowledge, this hypothesis has yet to be tested. Here, we assessed how site familiarity, measured as the intensity of use of a given location, is associated with the probability of roe deer Capreolus capreolus being killed by two predators with contrasting hunting tactics, the Eurasian lynx Lynx lynx and human hunters. While risk of human hunting was confined to open habitats, risk of lynx predation was more diffuse, with no clear refuge areas. We estimated cause-specific mortality rates in a competing risk framework for 212 GPS-collared roe deer in two ecologically distinct areas of Central Europe to test the hypothesis that the daily risk of being killed by lynx or hunters should be lower in areas of high familiarity. We found strong evidence that site familiarity reduces the risk of being predated by lynx, whereas the evidence that the risk of being hunted is linked to site familiarity was weak. We suggest that local knowledge about small-scale differences in predation risk and information about efficient escape routes affect an individual's ability to avoid or escape an attack by an ambush predator. Our study emphasizes the role of site familiarity in determining the susceptibility of prey to predation. Further research will be required to understand better how a cognitive map of individual spatial information is beneficial for avoiding predation in the arms race that drives the predator-prey shell game.

4.
Nat Commun ; 11(1): 1001, 2020 02 21.
Artigo em Inglês | MEDLINE | ID: mdl-32081890

RESUMO

Human activity has caused dramatic population declines in many wild species. The resulting bottlenecks have a profound impact on the genetic makeup of a species with unknown consequences for health. A key genetic factor for species survival is the evolution of deleterious mutation load, but how bottleneck strength and mutation load interact lacks empirical evidence. We analyze 60 complete genomes of six ibex species and the domestic goat. We show that historic bottlenecks rather than the current conservation status predict levels of genome-wide variation. By analyzing the exceptionally well-characterized population bottlenecks of the once nearly extinct Alpine ibex, we find genomic evidence of concurrent purging of highly deleterious mutations but accumulation of mildly deleterious mutations. This suggests that recolonization bottlenecks induced both relaxed selection and purging, thus reshaping the landscape of deleterious mutation load. Our findings highlight that even populations of ~1000 individuals can accumulate mildly deleterious mutations. Conservation efforts should focus on preventing population declines below such levels to ensure long-term survival of species.


Assuntos
Cabras/genética , Mutação , Animais , Animais Selvagens/classificação , Animais Selvagens/genética , Simulação por Computador , Conservação dos Recursos Naturais , Evolução Molecular , Variação Genética , Genética Populacional , Genoma , Cabras/classificação , Modelos Genéticos , Especificidade da Espécie , Tundra
5.
Phys Rev Lett ; 124(1): 017202, 2020 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-31976692

RESUMO

We report the discovery of topological magnetism in the candidate magnetic Weyl semimetal CeAlGe. Using neutron scattering we find this system to host several incommensurate, square-coordinated multi-k[over →] magnetic phases below T_{N}. The topological properties of a phase stable at intermediate magnetic fields parallel to the c axis are suggested by observation of a topological Hall effect. Our findings highlight CeAlGe as an exceptional system for exploiting the interplay between the nontrivial topologies of the magnetization in real space and Weyl nodes in momentum space.

6.
JACC Cardiovasc Interv ; 12(22): 2309-2316, 2019 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-31753302

RESUMO

OBJECTIVES: This study reports an international experience using the transfemoral ACURATE neo transcatheter heart valve (Boston Scientific, Marlborough, Massachusetts) for the treatment of degenerated surgical aortic bioprostheses. BACKGROUND: Transcatheter valve-in-valve procedures have emerged as an alternative to redo surgery. Supra-annular prostheses might be particularly useful in this indication. METHODS: This is an international multicenter analysis including 85 patients from 14 centers in Europe and Canada undergoing an ACURATE neo valve-in-valve procedure from March 2015 to February 2019. RESULTS: Internal diameter of the degenerated bioprosthesis was 20.3 ± 2.1 mm. Prosthesis size S was used in 70 (82%) procedures. The median depth of implantation was 3 mm and the upper crown of the ACURATE neo was positioned above the stent posts of the degenerated bioprosthesis in 54 (64%) and inside in 31 (36%). Mean transvalvular gradient before discharge was significantly lower if the upper crown was above the degenerated bioprosthesis (13.7 ± 5.9 mm Hg vs. 19.5 ± 10.0 mm Hg; p = 0.001). However, a high position of the ACURATE neo resulted in embolization in 1 patient, conversion to open-heart surgery in 1, and need for reintervention due to transcatheter heart valve failure within the first 18 months of follow-up in 4. CONCLUSIONS: This early experience shows that a high implantation of the ACURATE neo with the upper crown above the stent posts of the degenerated bioprosthesis resulted in lower mean transvalvular gradients but a higher rate of malpositioning and early valve degeneration.

7.
J Invasive Cardiol ; 31(10): E289-E297, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31567117

RESUMO

BACKGROUND: Acute kidney injury (AKI) post transcatheter aortic valve implantation (TAVI) is associated with worsened short- and long-term outcomes. We sought to identify significant baseline predictors of AKI and establish a high-risk group within patients enrolled in the multicenter SWISS-TAVI cohort. METHODS AND RESULTS: A total of 526 patients who underwent TAVI were included in our analysis. Patients on hemodialysis were excluded. Within the first week after valve implantation, fifty patients (9.5%) developed AKI. There was a significantly higher prevalence of diabetes mellitus in the AKI group (45% vs 28%; P=.02). The odds ratio (OR) for patients suffering from diabetes mellitus who developed AKI was 1.9 after multivariable binary regression analysis (95% confidence interval, 1.018-3.553; P=.04). Chronic kidney disease (CKD) stage ≥4 was more prevalent in the AKI group (26% vs 14%; P=.04). Every 1 mg/dL creatinine above normal level at baseline increased AKI risk by a factor of 1.6 (OR, 1.605; 95% CI, 1.111-2.319; P=.01). Age, gender, body mass index, history of dyslipidemia, and history of hypertension were similar between the groups. In the diabetic population of 155 patients (29.5%), AKI developed in 22 patients (14.2%), compared with the non-diabetic population of 370 patients (70.5%), where AKI developed in 27 patients (7.3%). In the diabetic population, an elevation by 1 mg/dL in baseline creatinine was an independent predictor of developing kidney injury (OR, 2.061; 95% CI, 1.154-3.683; P=.02, while in non-diabetic patients, neither baseline glomerular filtration rate, CKD grade, STS score, EuroScore II, ACEF score, nor procedural contrast usage were predictors of AKI. CONCLUSION: Diabetics with CKD stage ≥4 (as defined by the Kidney Disease: Improving Global Outcomes criteria) constitute a high-risk group for developing AKI after TAVI. In this high-risk subgroup, baseline creatinine in combination with amount of contrast agent used were strong risk factors for developing AKI. AKI in non-diabetics was less predictable by baseline characteristics.


Assuntos
Lesão Renal Aguda/epidemiologia , Estenose da Valva Aórtica/cirurgia , Complicações Pós-Operatórias/epidemiologia , Medição de Risco/métodos , Substituição da Valva Aórtica Transcateter/efeitos adversos , Lesão Renal Aguda/diagnóstico , Lesão Renal Aguda/etiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Creatinina/sangue , Feminino , Seguimentos , Taxa de Filtração Glomerular , Mortalidade Hospitalar , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Complicações Pós-Operatórias/diagnóstico , Complicações Pós-Operatórias/etiologia , Prognóstico , Estudos Retrospectivos , Fatores de Risco , Taxa de Sobrevida/tendências , Suíça/epidemiologia , Fatores de Tempo
8.
Nat Ecol Evol ; 3(9): 1359-1364, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31477848

RESUMO

Many studies document negative inbreeding effects on individuals, and conservation efforts to preserve rare species routinely employ strategies to reduce inbreeding. Despite this, there are few clear examples in nature of inbreeding decreasing the growth rates of populations, and the extent of population-level effects of inbreeding in the wild remains controversial. Here, we take advantage of a long-term dataset of 26 reintroduced Alpine ibex (Capra ibex ibex) populations spanning nearly 100 years to show that inbreeding substantially reduced per capita population growth rates, particularly for populations in harsher environments. Populations with high average inbreeding (F ≈ 0.2) had population growth rates reduced by 71% compared with populations with no inbreeding. Our results show that inbreeding can have long-term demographic consequences even when environmental variation is large and deleterious alleles may have been purged during bottlenecks. Thus, efforts to guard against inbreeding effects in populations of endangered species have not been misplaced.


Assuntos
Variação Genética , Endogamia , Animais , Conservação dos Recursos Naturais , Espécies em Perigo de Extinção , Cabras
9.
Evol Lett ; 3(3): 271-285, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31171983

RESUMO

Appropriately defining and enumerating "fitness" is fundamental to explaining and predicting evolutionary dynamics. Yet, general theoretical concepts of fitness are often hard to translate into quantities that can be measured in wild populations experiencing complex environmental, demographic, genetic, and selective variation. Although the "fittest" entities might be widely understood to be those that ultimately leave most descendants at some future time, such long-term legacies can rarely be measured, impeding evaluation of the degree to which tractable short-term metrics of individual fitness could potentially serve as useful direct proxies. One opportunity for conceptual and empirical convergence stems from the principle of individual reproductive value (V i), here defined as the number of copies of each of an individual's alleles that is expected to be present in future generations given the individual's realized pedigree of descendants. As V i tightly predicts an individual's longer term genetic contribution, quantifying V i provides a tractable route to quantifying what, to date, has been an abstract theoretical fitness concept. We used complete pedigree data from free-living song sparrows (Melospiza melodia) to demonstrate that individuals' expected genetic contributions stabilize within an observed 20-year (i.e. approximately eight generation) time period, allowing estimation of individual V i. Considerable among-individual variation in V i was evident in both sexes. Standard metrics of individual lifetime fitness, comprising lifespan, lifetime reproductive success, and projected growth rate, typically explained less than half the variation. We thereby elucidate the degree to which fitness metrics observed on individuals concur with measures of longer term genetic contributions and consider the degree to which analyses of pedigree structure could provide useful complementary insights into evolutionary outcomes.

11.
Genet Sel Evol ; 51(1): 7, 2019 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-30819110

RESUMO

BACKGROUND: The animal model is a key tool in quantitative genetics and has been used extensively to estimate fundamental parameters, such as additive genetic variance or heritability. An implicit assumption of animal models is that all founder individuals derive from a single population. This assumption is commonly violated, for instance in crossbred livestock or when a meta-population is split into genetically differentiated subpopulations. Ignoring that base populations are genetically heterogeneous and thus split into different 'genetic groups' may lead to biased parameter estimates, especially for additive genetic variance. To avoid such biases, genetic group animal models, which account for the presence of more than one genetic group, have been proposed. Unfortunately, the method to date is only computationally feasible when the breeding values of the groups are allowed to differ in their means, but not in their variances. RESULTS: We present an extension of the animal model that permits estimation of group-specific additive genetic variances. This is achieved by employing group-specific relatedness matrices for the breeding value components to different genetic groups. We derive these matrices by decomposing the full relatedness matrix via the generalized Cholesky decomposition, and by scaling the respective matrix components for each group. We propose a computationally convenient approximation for the matrix component that encodes for the Mendelian sampling variance, and show that this approximation is not critical. In addition, we explain why segregation variances are often negligible when analyzing the complex polygenic traits that are frequently the focus of evolutionary ecologists and animal breeders. Simulations and an example from an insular meta-population of house sparrows in Norway with three distinct genetic groups illustrate that the method is successful in estimating group-specific additive genetic variances, and that segregation variances are indeed negligible in the empirical example. CONCLUSIONS: Quantifying differences in additive genetic variance within and among populations is of major biological interest in ecology, evolution, and animal and plant breeding. The proposed method allows to estimate such differences for subpopulations that form a connected set of populations, and may thus also be useful to study temporal or spatial variation of additive genetic variances.


Assuntos
Cruzamento/métodos , Gado/genética , Modelos Genéticos , Polimorfismo Genético , Animais , Feminino , Masculino
12.
Evol Appl ; 12(2): 266-279, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30697338

RESUMO

Inbreeding depression, the deterioration in mean trait value in progeny of related parents, is a fundamental quantity in genetics, evolutionary biology, animal and plant breeding, and conservation biology. The magnitude of inbreeding depression can be quantified by the inbreeding load, typically measured in numbers of lethal equivalents, a population genetic quantity that allows for comparisons between environments, populations or species. However, there is as yet no quantitative assessment of which combinations of statistical models and metrics of inbreeding can yield such estimates. Here, we review statistical models that have been used to estimate inbreeding load and use population genetic simulations to investigate how unbiased estimates can be obtained using genomic and pedigree-based metrics of inbreeding. We use simulated binary viability data (i.e., dead versus alive) as our example, but the concepts apply to any trait that exhibits inbreeding depression. We show that the increasingly popular generalized linear models with logit link do not provide comparable and unbiased population genetic measures of inbreeding load, independent of the metric of inbreeding used. Runs of homozygosity result in unbiased estimates of inbreeding load, whereas inbreeding measured from pedigrees results in slight overestimates. Due to widespread use of models that do not yield unbiased measures of the inbreeding load, some estimates in the literature cannot be compared meaningfully. We surveyed the literature for reliable estimates of the mean inbreeding load from wild vertebrate populations and found an average of 3.5 haploid lethal equivalents for survival to sexual maturity. To obtain comparable estimates, we encourage researchers to use generalized linear models with logarithmic links or maximum-likelihood estimation of the exponential equation, and inbreeding coefficients calculated from runs of homozygosity, provided an assembled reference genome of sufficient quality and enough genetic marker data are available.

13.
Beilstein J Nanotechnol ; 9: 2581-2598, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30345218

RESUMO

Fabrication of three-dimensional (3D) nanoarchitectures by focused electron beam induced deposition (FEBID) has matured to a level that highly complex and functional deposits are becoming available for nanomagnetics and plasmonics. However, the generation of suitable pattern files that control the electron beam's movement, and thereby reliably map the desired target 3D structure from a purely geometrical description to a shape-conforming 3D deposit, is nontrivial. To address this issue we developed several writing strategies and associated algorithms implemented in C++. Our pattern file generator handles different proximity effects and corrects for height-dependent precursor coverage. Several examples of successful 3D nanoarchitectures using different precursors are presented that validate the effectiveness of the implementation.

14.
Evolution ; 72(10): 2057-2075, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30101430

RESUMO

Quantifying sex-specific additive genetic variance (VA ) in fitness, and the cross-sex genetic correlation (rA ), is prerequisite to predicting evolutionary dynamics and the magnitude of sexual conflict. Further, quantifying VA and rA in underlying fitness components, and genetic consequences of immigration and resulting gene flow, is required to identify mechanisms that maintain VA in fitness. However, these key parameters have rarely been estimated in wild populations experiencing natural environmental variation and immigration. We used comprehensive pedigree and life-history data from song sparrows (Melospiza melodia) to estimate VA and rA in sex-specific fitness and underlying fitness components, and to estimate additive genetic effects of immigrants alongside inbreeding depression. We found evidence of substantial VA in female and male fitness, with a moderate positive cross-sex rA . There was also substantial VA in male but not female adult reproductive success, and moderate VA in juvenile survival but not adult annual survival. Immigrants introduced alleles with negative additive genetic effects on local fitness, potentially reducing population mean fitness through migration load, but alleviating expression of inbreeding depression. Our results show that VA for fitness can be maintained in the wild, and be broadly concordant between the sexes despite marked sex-specific VA in reproductive success.


Assuntos
Aptidão Genética , Variação Genética , Endogamia , Longevidade , Reprodução , Aves Canoras/fisiologia , Distribuição Animal , Animais , Teorema de Bayes , Feminino , Masculino , Modelos Biológicos , Fatores Sexuais , Pardais/fisiologia
15.
Evolution ; 72(10): 1992-2004, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30107046

RESUMO

Quantitative genetic analyses require extensive measurements of phenotypic traits, a task that is often not trivial, especially in wild populations. On top of instrumental measurement error, some traits may undergo transient (i.e., nonpersistent) fluctuations that are biologically irrelevant for selection processes. These two sources of variability, which we denote here as measurement error in a broad sense, are possible causes for bias in the estimation of quantitative genetic parameters. We illustrate how in a continuous trait transient effects with a classical measurement error structure may bias estimates of heritability, selection gradients, and the predicted response to selection. We propose strategies to obtain unbiased estimates with the help of repeated measurements taken at an appropriate temporal scale. However, the fact that in quantitative genetic analyses repeated measurements are also used to isolate permanent environmental instead of transient effects requires that the information content of repeated measurements is carefully assessed. To this end, we propose to distinguish "short-term" from "long-term" repeats, where the former capture transient variability and the latter help isolate permanent effects. We show how the inclusion of the corresponding variance components in quantitative genetic models yields unbiased estimates of all quantities of interest, and we illustrate the application of the method to data from a Swiss snow vole population.


Assuntos
Arvicolinae/genética , Evolução Biológica , Fenótipo , Característica Quantitativa Herdável , Seleção Genética , Animais , Modelos Animais , Modelos Genéticos , Suíça
16.
Evol Appl ; 11(5): 631-644, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29875807

RESUMO

Crucial for the long-term survival of wild populations is their ability to fight diseases. Disease outbreaks can lead to severe population size reductions, which makes endangered and reintroduced species especially vulnerable. In vertebrates, the major histocompatibility complex (MHC) plays an important role in determining the immune response. Species that went through severe bottlenecks often show very low levels of genetic diversity at the MHC. Due to the known link between the MHC and immune response, such species are expected to be at particular risk in case of disease outbreaks. However, so far, only few studies have shown that low MHC diversity is correlated with increased disease susceptibility in species after severe bottlenecks. We investigated genetic variation at the MHC and its correlations with disease resistance and other fitness-related traits in Alpine ibex (Capra ibex), a wild goat species that underwent a strong bottleneck in the last century and that is known to have extremely low genetic variability, both genome-wide and at the MHC. We studied MHC variation in male ibex of Gran Paradiso National Park, the population used as a source for all postbottleneck reintroductions. We found that individual MHC heterozygosity (based on six microsatellites) was not correlated with genome-wide neutral heterozygosity. MHC heterozygosity, but not genome-wide heterozygosity, was positively correlated with resistance to infectious keratoconjunctivitis and with body mass. Our results show that genetic variation at the MHC plays an important role in disease resistance and, hence, should be taken into account for successfully managing species conservation.

17.
Sci Rep ; 8(1): 9129, 2018 06 14.
Artigo em Inglês | MEDLINE | ID: mdl-29904085

RESUMO

The Niata was a cattle variety from South America that figured prominently in writings on evolution by Charles Darwin. Its shortened head and other aspects of its unusual morphology have been subject of unsettled discussions since Darwin's time. Here, we examine the anatomy, cranial shape, skull biomechanics, and population genetics of the Niata. Our results show that the Niata was a viable variety of cattle and exhibited anatomical differences to known chondrodysplastic forms. In cranial shape and genetic analysis, the Niata occupies an isolated position clearly separated from other cattle. Computational biomechanical model comparison reveals that the shorter face of the Niata resulted in a restricted distribution and lower magnitude of stress during biting. Morphological and genetic data illustrate the acquisition of novelty in the domestication process and confirm the distinct nature of the Niata cattle, validating Darwin's view that it was a true breed.


Assuntos
Evolução Biológica , Bovinos , Simulação por Computador , Modelos Biológicos , Seleção Artificial , Crânio , Animais , Bovinos/anatomia & histologia , Bovinos/genética , Feminino , Masculino , Crânio/anatomia & histologia , Crânio/fisiologia , América do Sul
18.
Sci Rep ; 8(1): 6160, 2018 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-29670129

RESUMO

By the fabrication of periodically arranged nanomagnetic systems it is possible to engineer novel physical properties by realizing artificial lattice geometries that are not accessible via natural crystallization or chemical synthesis. This has been accomplished with great success in two dimensions in the fields of artificial spin ice and magnetic logic devices, to name just two. Although first proposals have been made to advance into three dimensions (3D), established nanofabrication pathways based on electron beam lithography have not been adapted to obtain free-form 3D nanostructures. Here we demonstrate the direct-write fabrication of freestanding ferromagnetic 3D nano-architectures. By employing micro-Hall sensing, we have determined the magnetic stray field generated by our free-form structures in an externally applied magnetic field and we have performed micromagnetic and macro-spin simulations to deduce the spatial magnetization profiles in the structures and analyze their switching behavior. Furthermore we show that the magnetic 3D elements can be combined with other 3D elements of different chemical composition and intrinsic material properties.

19.
Evol Appl ; 11(2): 123-139, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29387150

RESUMO

Restoration of lost species ranges to their native distribution is key for the survival of endangered species. However, reintroductions often fail and long-term genetic consequences are poorly understood. Alpine ibex (Capra ibex) are wild goats that recovered from <100 individuals to ~50,000 within a century by population reintroductions. We analyzed the population genomic consequences of the Alpine ibex reintroduction strategy. We genotyped 101,822 genomewide single nucleotide polymorphism loci in 173 Alpine ibex, the closely related Iberian ibex (Capra pyrenaica) and domestic goat (Capra hircus). The source population of all Alpine ibex maintained genetic diversity comparable to Iberian ibex, which experienced less severe bottlenecks. All reintroduced Alpine ibex populations had individually and combined lower levels of genetic diversity than the source population. The reintroduction strategy consisted of primary reintroductions from captive breeding and secondary reintroductions from established populations. This stepwise reintroduction strategy left a strong genomic footprint of population differentiation, which increased with subsequent rounds of reintroductions. Furthermore, analyses of genomewide runs of homozygosity showed recent inbreeding primarily in individuals of reintroduced populations. We showed that despite the rapid census recovery, Alpine ibex carry a persistent genomic signature of their reintroduction history. We discuss how genomic monitoring can serve as an early indicator of inbreeding.

20.
Inorg Chem ; 57(9): 4934-4943, 2018 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-29389126

RESUMO

Two Cu2+ coordination polymers [CuCl(pyz)2](BF4) 1 and [CuBr(pyz)2](BF4) 2 (pyz = pyrazine) were synthesized in the family of quasi two-dimensional (2D) [Cu(pyz)2]2+ magnetic networks. The layer connectivity by monatomic halide ligands results in significantly shorter interlayer distances. Structures were determined by single-crystal X-ray diffraction. Temperature-dependent X-ray diffraction of 1 revealed rigid [Cu(pyz)2]2+ layers that do not expand between 5 K and room temperature, whereas the expansion along the c-axis amounts to 2%. The magnetic susceptibility of 1 and 2 shows a broad maximum at ∼8 K, indicating antiferromagnetic interactions within the [Cu(pyz)2]2+ layers. 2D Heisenberg model fits result in J∥ = 9.4(1) K for 1 and 8.9(1) K for 2. The interlayer coupling is much weaker with | J⊥| = 0.31(6) K for 1 and 0.52(9) K for 2. The electron density, experimentally determined and calculated by density functional theory, confirms the location of the singly occupied orbital (the magnetic orbital) in the tetragonal plane. The analysis of the spin density reveals a mainly σ-type exchange through pyrazine. Kinks in the magnetic susceptibility indicate the onset of long-range three-dimensional magnetic order below 4 K. The magnetic structures were determined by neutron diffraction. Magnetic Bragg peaks occur below TN = 3.9(1) K for 1 and 3.8(1) K for 2. The magnetic unit cell is doubled along the c-axis ( k = 0, 0, 0.5). The ordered magnetic moments are located in the tetragonal plane and amount to 0.76(8) µB/Cu2+ for 1 and 0.6(1) µB/Cu2+ for 2 at 1.5 K. The moments are coupled antiferromagnetically both in the ab plane and along the c-axis. The Cu2+ g-tensor was determined from electron spin resonance spectra as g x = 2.060(1), g z = 2.275(1) for 1 and g x = 2.057(1), g z = 2.272(1) for 2 at room temperature.

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