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1.
Proc Natl Acad Sci U S A ; 120(19): e2219345120, 2023 05 09.
Artículo en Inglés | MEDLINE | ID: mdl-37126712

RESUMEN

Although over 50 y have passed since W. D. Hamilton articulated kin selection and inclusive fitness as evolutionary explanations for altruistic behavior, quantifying inclusive fitness continues to be challenging. Here, using 30 y of data and two alternative methods, we outline an approach to measure lifetime inclusive fitness effects of cooperative polygamy (mate-sharing or cobreeding) in the cooperatively breeding acorn woodpecker Melanerpes formicivorus. For both sexes, the number of offspring (observed direct fitness) declined while the number of young parented by related cobreeders (observed indirect fitness effect) increased with cobreeding coalition size. Combining these two factors, the observed inclusive fitness effect of cobreeding was greater than breeding singly for males, while the pattern for females depended on whether fitness was age-weighted, as females breeding singly accrued greater fitness at younger ages than cobreeding females. Accounting for the fitness birds would have obtained by breeding singly, however, lifetime inclusive fitness effects declined with coalition size for males, but were greater for females breeding as duos compared to breeding singly, due largely to indirect fitness effects of kin. Our analyses provide a road map for, and demonstrate the importance of, quantifying indirect fitness as a powerful evolutionary force contributing to the costs and benefits of social behaviors.


Asunto(s)
Aves , Matrimonio , Animales , Femenino , Masculino , Conducta Social , Reproducción , Altruismo , Conducta Cooperativa
2.
Proc Natl Acad Sci U S A ; 120(19): e2208389120, 2023 05 09.
Artículo en Inglés | MEDLINE | ID: mdl-37126701

RESUMEN

Climate change affects timing of reproduction in many bird species, but few studies have investigated its influence on annual reproductive output. Here, we assess changes in the annual production of young by female breeders in 201 populations of 104 bird species (N = 745,962 clutches) covering all continents between 1970 and 2019. Overall, average offspring production has declined in recent decades, but considerable differences were found among species and populations. A total of 56.7% of populations showed a declining trend in offspring production (significant in 17.4%), whereas 43.3% exhibited an increase (significant in 10.4%). The results show that climatic changes affect offspring production through compounded effects on ecological and life history traits of species. Migratory and larger-bodied species experienced reduced offspring production with increasing temperatures during the chick-rearing period, whereas smaller-bodied, sedentary species tended to produce more offspring. Likewise, multi-brooded species showed increased breeding success with increasing temperatures, whereas rising temperatures were unrelated to reproductive success in single-brooded species. Our study suggests that rapid declines in size of bird populations reported by many studies from different parts of the world are driven only to a small degree by changes in the production of young.


Asunto(s)
Cambio Climático , Rasgos de la Historia de Vida , Animales , Femenino , Estaciones del Año , Pollos , Reproducción
3.
Proc Natl Acad Sci U S A ; 119(3)2022 01 18.
Artículo en Inglés | MEDLINE | ID: mdl-34983867

RESUMEN

Tree fecundity and recruitment have not yet been quantified at scales needed to anticipate biogeographic shifts in response to climate change. By separating their responses, this study shows coherence across species and communities, offering the strongest support to date that migration is in progress with regional limitations on rates. The southeastern continent emerges as a fecundity hotspot, but it is situated south of population centers where high seed production could contribute to poleward population spread. By contrast, seedling success is highest in the West and North, serving to partially offset limited seed production near poleward frontiers. The evidence of fecundity and recruitment control on tree migration can inform conservation planning for the expected long-term disequilibrium between climate and forest distribution.


Asunto(s)
Cambio Climático , Árboles/fisiología , Ecosistema , Fertilidad/fisiología , Geografía , América del Norte , Incertidumbre
4.
Am Nat ; 203(3): E92-E106, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38358808

RESUMEN

AbstractPeriodical cicadas live 13 or 17 years underground as nymphs, then emerge in synchrony as adults to reproduce. Developmentally synchronized populations called broods rarely coexist, with one dominant brood locally excluding those that emerge in off years. Twelve modern 17-year cicada broods are believed to have descended from only three ancestral broods following the last glaciation. The mechanisms by which these daughter broods overcame exclusion by the ancestral brood to synchronously emerge in a different year, however, are elusive. Here, we demonstrate that temporal variation in the population density of generalist predators can allow intermittent opportunities for new broods to invade, even though a single brood remains dominant most of the time. We show that this mechanism is consistent, in terms of the type and frequency of brood replacements, with the distribution of periodical cicada broods throughout North America today. Although we investigate one particularly charismatic case study, the mechanisms involved (competitive exclusion, Allee effects, trait variation, predation, and temporal variability) are ubiquitous and could contribute to patterns of species diversity in a range of systems.


Asunto(s)
Hemípteros , Animales , Conducta Predatoria , Ninfa , América del Norte
5.
Oecologia ; 204(4): 975-984, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38597960

RESUMEN

Seabirds create fluxes of nutrients from marine to terrestrial ecosystems that influence the food webs of small islands. We investigated how guano inputs shape terrestrial food webs by comparing species of selected plant and animal species in a red-footed booby colony in Mona Island (Puerto Rico, Caribbean Sea), to sites of the island lacking guano inputs. We quantified guano deposition and its relationship to plant biomass production, fecundity and density, as well as the activity of native and introduced animal species. In general, guano inputs increased the gross primary plant productivity, size, and fecundity by twofold. Guano inputs were also associated with twofold increases in density of Anole lizards, but also to increases in the activity of introduced pigs (> 500%), goats (> 30%), and cats (> 500%), which negatively impact native species. In particular, elevated pig and cat activity within the booby colony was correlated with lower activity of endemic ground lizards and of introduced rats. Our results also suggest that severe droughts associated with climate change exacerbate the negative effects that introduced species have on vegetation and reduce the positive effects of seabird guano inputs. Our findings underscore the importance of allochthonous guano inputs in subsidizing plant productivity and native and endemic species in small oceanic islands, but also in increasing the negative impacts of introduced mammals. Management and conservation efforts should focus on the exclusion (or eradication) of introduced mammals, particularly pigs and goats, from remnant seabird colonies in Mona Island.


Asunto(s)
Aves , Especies Introducidas , Islas , Mamíferos , Animales , Cadena Alimentaria , Ecosistema , Plantas , Heces
6.
Proc Natl Acad Sci U S A ; 118(34)2021 08 24.
Artículo en Inglés | MEDLINE | ID: mdl-34400503

RESUMEN

Despite its importance for forest regeneration, food webs, and human economies, changes in tree fecundity with tree size and age remain largely unknown. The allometric increase with tree diameter assumed in ecological models would substantially overestimate seed contributions from large trees if fecundity eventually declines with size. Current estimates are dominated by overrepresentation of small trees in regression models. We combined global fecundity data, including a substantial representation of large trees. We compared size-fecundity relationships against traditional allometric scaling with diameter and two models based on crown architecture. All allometric models fail to describe the declining rate of increase in fecundity with diameter found for 80% of 597 species in our analysis. The strong evidence of declining fecundity, beyond what can be explained by crown architectural change, is consistent with physiological decline. A downward revision of projected fecundity of large trees can improve the next generation of forest dynamic models.


Asunto(s)
Fertilidad , Modelos Biológicos , Regeneración , Árboles/crecimiento & desarrollo , Bosques
7.
J Am Soc Nephrol ; 34(2): 346-358, 2023 02 01.
Artículo en Inglés | MEDLINE | ID: mdl-36396330

RESUMEN

SIGNIFICANCE STATEMENT: Glomerular volume, ischemic glomeruli, and global glomerulosclerosis are not consistently assessed on kidney transplant biopsies. The authors evaluated morphometric measures of glomerular volume, the percentage of global glomerulosclerosis, and the percentage of ischemic glomeruli and assessed changes in these measures over time to determine whether such changes predict late allograft failure. All three features increased from transplant to five-year biopsy. Kidneys with smaller glomeruli at 5 years had more global glomerulosclerosis and a higher percentage of ischemic-appearing glomeruli. Smaller glomeruli and increasing percentages of global glomerulosclerosis and ischemic glomeruli at 5 years predicted allograft failure. Only increased percentage of ischemic glomeruli predicted allograft failure at 5 years independent of all Banff scores. Glomerular changes reflect pathologic processes that predicted allograft loss; measuring them quantitatively might enhance the current Banff system and provide biomarkers for intervention trials. BACKGROUND: Histology can provide insight into the biology of renal allograft loss. However, studies are lacking that use quantitative morphometry to simultaneously assess changes in mean glomerular volume and in the percentages of globally sclerosed glomeruli (GSG) and ischemic-appearing glomeruli in surveillance biopsies over time to determine whether such changes are correlated with late graft failure. METHODS: We used digital scans of surveillance biopsies (at implantation and at 1 and 5 years after transplantation) to morphometrically quantify glomerular volume and the percentages of GSG and ischemic-appearing glomeruli in a cohort of 835 kidney transplants. Cox proportional hazards models assessed the risk of allograft failure with these three glomerular features. RESULTS: From implantation to 5 years, mean glomerular volume increased by nearly 30% (from 2.8×10 6 to 3.6×10 6 µm 3 ), mean percentage of GSG increased from 3.2% to 13.2%, and mean percentage of ischemic-appearing glomeruli increased from 0.8% to 9.5%. Higher percentages of GSG and ischemic-appearing glomeruli at 5-year biopsy predicted allograft loss. The three glomerular features at 5-year biopsy were related; the percentage of GSG and the percentage of ischemic glomeruli were positively correlated, and both were inversely correlated to glomerular volume. At 5 years, only 5.3% of biopsies had ≥40% ischemic glomeruli, but 45% of these grafts failed (versus 11.6% for <40% ischemic glomeruli). Higher Banff scores were more common with increasing percentages of GSG and ischemia, but at 5 years, only the percentage of ischemic glomeruli added to predictive models adjusted for Banff scores. CONCLUSIONS: Glomerular changes reflect important pathologic processes that predict graft loss. Measuring glomerular changes quantitatively on surveillance biopsies, especially the proportion of ischemic-appearing glomeruli, may enhance the current Banff system and be a useful surrogate end point for clinical intervention trials. PODCAST: This article contains a podcast at.


Asunto(s)
Enfermedades Renales , Trasplante de Riñón , Humanos , Trasplante de Riñón/efectos adversos , Esclerosis/patología , Incidencia , Riñón/patología , Enfermedades Renales/patología , Biopsia , Biomarcadores/análisis , Isquemia/etiología , Isquemia/patología , Rechazo de Injerto/epidemiología , Rechazo de Injerto/etiología
8.
Arch Orthop Trauma Surg ; 144(5): 2207-2212, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38520550

RESUMEN

INTRODUCTION: The use of barbed sutures for wound closure in primary total joint arthroplasty (TJA) has been shown to be effective and safe. However, their effectiveness and safety in revision TJA procedures has not been thoroughly studied. This study aims to evaluate the efficacy and safety of using barbed suture closure in revision TJA setting. METHODS: A total of 80 patients undergoing revision TJA between September 2020 and November 2022 were included in this randomized controlled trial study. Following informed consent, patients were computer-randomized to the treatment arm (barbed suture wound closure) or to the control arm (conventional wound closure). Closure duration, closure rate, number of sutures used and wound related outcomes including complication rates and Patient and Observer Scar Assessment Scale (POSAS) score were compared between groups. RESULTS: The use of barbed sutures decreased closure time by 6 min (30.1 vs. 36.1 min, P = 0.008) with a higher wound closure rate (6.5 vs. 5.5 mm/minute, P = 0.013). Additionally, the number of sutures used for wound closure in the barbed group was significantly lower than in the control group (6.2 vs. 10.1, respectively, P < 0.001). There were no significant differences in the rate of postoperative wound complications (P = 0.556) or patient and observer POSAS scores (P = 0.211, P = 297, respectively) between the two groups at 3-month follow-up. CONCLUSION: Closure of revision TJA surgical wound utilizing barbed sutures reduced closure time and the number of needles handled by operative staff, with no significant increase in intra- or post-operative complications rate when compared to traditional closure technique. LEVEL OF EVIDENCE: I.


Asunto(s)
Reoperación , Técnicas de Sutura , Suturas , Humanos , Femenino , Masculino , Reoperación/estadística & datos numéricos , Estudios Prospectivos , Persona de Mediana Edad , Anciano , Complicaciones Posoperatorias/epidemiología
9.
Int J Psychol ; 2024 Mar 28.
Artículo en Inglés | MEDLINE | ID: mdl-38548474

RESUMEN

We review Bandura's contributions to cognitive-behavioural theory, research and practice. His basic research on the causal role of cognitive processes in social learning was a major factor in the emergence of cognitive-behavioural therapies in the 1970s. His investigations on observational learning and self-efficacy beliefs led to the development of guided mastery therapy, a specific cognitive-behavioural intervention for anxiety disorders. His research on self-regulatory processes provided an empirical basis for the emergence of numerous therapies targeting self-regulation. We conclude by discussing how Bandura's social cognitive theory, as well as more recent advances in social cognitive theorising, might be further applied to innovative approaches to therapeutic interventions, assessment and clinical case conceptualization.

10.
Am Nat ; 201(5): 755-762, 2023 05.
Artículo en Inglés | MEDLINE | ID: mdl-37130235

RESUMEN

AbstractOaks (Quercus spp.) are masting species exhibiting highly variable and synchronized acorn production. We investigated the hypothesis that periodical cicadas (Magicada spp.), well known to have strong effects on the ecosystems in which they occur, affect acorn production of oaks through their xylem feeding habits as nymphs, the oviposition damage they inflict as adults during emergences, or the nutrient pulse resulting from the decomposition of their bodies following breeding. We found negative effects on acorn production during emergence years and the year following emergences and enhanced acorn production 2 years after emergence. We also found evidence indicating a significant effect of cicada emergences on spatial synchrony of acorn production by trees growing within the range of the same cicada brood compared with different broods. These results demonstrate that periodical cicadas act as a trophic environmental "veto" depressing acorn production during and immediately following emergences, after which the nutrient pulse associated with the cicada's demise enhances oak reproduction.


Asunto(s)
Hemípteros , Quercus , Animales , Femenino , Ecosistema , Reproducción , Árboles , Semillas
11.
Phys Rev Lett ; 130(22): 221502, 2023 Jun 02.
Artículo en Inglés | MEDLINE | ID: mdl-37327450

RESUMEN

We present a new avenue to black hole evaporation using a heat-kernel approach analogous as for the Schwinger effect. Applying this method to an uncharged massless scalar field in a Schwarzschild spacetime, we show that spacetime curvature takes a similar role as the electric field strength in the Schwinger effect. We interpret our results as local pair production in a gravitational field and derive a radial production profile. The resulting emission peaks near the unstable photon orbit. Comparing the particle number and energy flux to the Hawking case, we find both effects to be of similar order. However, our pair production mechanism itself does not explicitly make use of the presence of a black hole event horizon.


Asunto(s)
Electricidad , Calor , Fotones
12.
Phys Rev Lett ; 130(21): 212701, 2023 May 26.
Artículo en Inglés | MEDLINE | ID: mdl-37295108

RESUMEN

The rate of the final step in the astrophysical αp process, the ^{34}Ar(α,p)^{37}K reaction, suffers from large uncertainties due to a lack of experimental data, despite having a considerable impact on the observable light curves of x-ray bursts and the composition of the ashes of hydrogen and helium burning on accreting neutron stars. We present the first direct measurement constraining the ^{34}Ar(α,p)^{37}K reaction cross section, using the Jet Experiments in Nuclear Structure and Astrophysics gas jet target. The combined cross section for the ^{34}Ar,Cl(α,p)^{37}K,Ar reaction is found to agree well with Hauser-Feshbach predictions. The ^{34}Ar(α,2p)^{36}Ar cross section, which can be exclusively attributed to the ^{34}Ar beam component, also agrees to within the typical uncertainties quoted for statistical models. This indicates the applicability of the statistical model for predicting astrophysical (α,p) reaction rates in this part of the αp process, in contrast to earlier findings from indirect reaction studies indicating orders-of-magnitude discrepancies. This removes a significant uncertainty in models of hydrogen and helium burning on accreting neutron stars.


Asunto(s)
Helio , Hidrógeno , Modelos Estadísticos , Neutrones
13.
Am J Geriatr Psychiatry ; 31(12): 1017-1031, 2023 12.
Artículo en Inglés | MEDLINE | ID: mdl-37798224

RESUMEN

This position statement of the Expert Panel on Brain Health of the American Association for Geriatric Psychiatry (AAGP) emphasizes the critical role of life course brain health in shaping mental well-being during the later stages of life. Evidence posits that maintaining optimal brain health earlier in life is crucial for preventing and managing brain aging-related disorders such as dementia/cognitive decline, depression, stroke, and anxiety. We advocate for a holistic approach that integrates medical, psychological, and social frameworks with culturally tailored interventions across the lifespan to promote brain health and overall mental well-being in aging adults across all communities. Furthermore, our statement underscores the significance of prevention, early detection, and intervention in identifying cognitive decline, mood changes, and related mental illness. Action should also be taken to understand and address the needs of communities that traditionally have unequal access to preventive health information and services. By implementing culturally relevant and tailored evidence-based practices and advancing research in geriatric psychiatry, behavioral neurology, and geroscience, we can enhance the quality of life for older adults facing the unique challenges of aging. This position statement emphasizes the intrinsic link between brain health and mental health in aging, urging healthcare professionals, policymakers, and a broader society to prioritize comprehensive strategies that safeguard and promote brain health from birth through later years across all communities. The AAGP Expert Panel has the goal of launching further activities in the coming months and years.


Asunto(s)
Salud Mental , Calidad de Vida , Humanos , Estados Unidos , Anciano , Psiquiatría Geriátrica , Acontecimientos que Cambian la Vida , Encéfalo
14.
Clin Transplant ; 37(8): e14987, 2023 08.
Artículo en Inglés | MEDLINE | ID: mdl-37026820

RESUMEN

BACKGROUND: The aim of this study was to correlate peripheral blood gene expression profile (GEP) results during the first post-transplant year with outcomes after kidney transplantation. METHODS: We conducted a prospective, multicenter observational study of obtaining peripheral blood at five timepoints during the first post-transplant year to perform a GEP assay. The cohort was stratified based on the pattern of the peripheral blood GEP results: Tx-all GEP results normal, 1 Not-TX had one GEP result abnormal and >1 Not-TX two or more abnormal GEP results. We correlated the GEP results with outcomes after transplantation. RESULTS: We enrolled 240 kidney transplant recipients. The cohort was stratified into the three groups: TX n = 117 (47%), 1 Not-TX n = 59 (25%) and >1 Not-TX n = 64 (27%). Compared to the TX group, the >1 Not-TX group had lower eGFR (p < .001) and more chronic changes on 1-year surveillance biopsy (p = .007). Death censored graft survival showed inferior graft survival in the >1 Not-TX group (p < .001) but not in the 1 Not-TX group. All graft losses in the >1 Not-TX group occurred after 1-year post-transplant. CONCLUSIONS: We conclude that a pattern of persistently Not-TX GEP assay correlates with inferior graft survival.


Asunto(s)
Trasplante de Riñón , Humanos , Trasplante de Riñón/efectos adversos , Estudios Prospectivos , Expresión Génica , Supervivencia de Injerto , Rechazo de Injerto/etiología , Rechazo de Injerto/genética
15.
Inorg Chem ; 62(23): 9146-9157, 2023 Jun 12.
Artículo en Inglés | MEDLINE | ID: mdl-37228171

RESUMEN

A series of dinuclear molecular copper complexes were prepared and used to model the binding and Lewis acid stabilization of CO in heterogeneous copper CO2 reduction electrocatalysts. Experimental studies (including measurement of rate and equilibrium constants) and electronic structure calculations suggest that the key kinetic barrier for CO binding may be a σ-interaction between CuI and the incoming CO ligand. The rate of CO coordination can be increased upon the addition of Lewis acids or electron-withdrawing substituents on the ligand backbone. Conversely, Keq for CO coordination can be increased by adding electron density to the metal centers of the compound, consistent with stronger π-backbonding. Finally, the electrochemically measured kinetic results were mapped onto an electrochemical zone diagram to illustrate how these system changes enabled access to each zone.

16.
Environ Sci Technol ; 57(45): 17266-17277, 2023 11 14.
Artículo en Inglés | MEDLINE | ID: mdl-37924285

RESUMEN

The iron phosphate mineral vivianite Fe(II)3(PO4)2·8H2O has emerged as a potential renewable P source. Although the importance of vivianite as a potential P sink in the global P cycle had previously been recognized, a mechanistic understanding of vivianite dissolution at the molecular level, critical to its potential application, is still elusive. The potential of vivianite as a P sink or source in natural or engineered systems is directly dependent on its dissolution kinetics under environmentally relevant conditions. To understand the thermodynamic and kinetic controls on bioavailability, the oxidation and dissolution processes of vivianite must be disentangled. In this study, we conducted controlled batch and flow-through experiments to quantitatively determine the dissolution rates and mechanisms of vivianite under anoxic conditions as a function of pH and temperature. Our results demonstrate that vivianite solubility and dissolution rates strongly decreased with increasing solution pH. Dissolution was nonstoichiometric at alkaline pH (>7). The rapid initial dissolution rate of vivianite is related to the solution saturation state, indicating a thermodynamic rather than a kinetic control. A defect-driven dissolution mechanism is proposed. Dissolution kinetics over pH 5-9 could be described with a rate law with a single rate constant and a reaction order of 0.61 with respect to {H+}: Rexp=36.0·e-1.41·pH·[1-e(0.2·ΔG/RT)]4.7 The activation energy of vivianite dissolution proved low (Ea = 20.3 kJ mol-1), suggesting hydrogen bridge dissociation as the rate-determining step.


Asunto(s)
Compuestos Ferrosos , Fosfatos , Compuestos Ferrosos/química , Fosfatos/química , Minerales/química , Oxidación-Reducción
17.
Environ Sci Technol ; 57(42): 16006-16015, 2023 10 24.
Artículo en Inglés | MEDLINE | ID: mdl-37819156

RESUMEN

Anthropogenic and biogenic ligands may mobilize uranium (U) from tetravalent U (U(IV)) phases in the subsurface, especially from labile noncrystalline U(IV). The rate and extent of U(IV) mobilization are affected by geochemical processes. Competing metals and humic substances may play a decisive role in U mobilization by anthropogenic and biogenic ligands. A structurally diverse set of anthropogenic and biogenic ligands was selected for assessing the effect of the aforementioned processes on U mobilization from noncrystalline U(IV), including 2,6-pyridinedicarboxylic acid (DPA), citrate, N,N'-di(2-hydroxybenzyl)ethylene-diamine-N,N'-diacetic acid (HBED), and desferrioxamine B (DFOB). All experiments were performed under anoxic conditions at pH 7.0. The effect of competing metals (Ca, Fe(III), and Zn) on ligand-induced U mobilization depended on the particular metal-ligand combination ranging from nearly complete U mobilization inhibition (e.g., Ca-citrate) to no apparent inhibitory effects or acceleration of U mobilization (e.g., Fe(III)-citrate). Humic substances (Suwannee River humic acid and fulvic acid) were tested across a range of concentrations either separately or combined with the aforementioned ligands. Humic substances alone mobilized appreciable U and also enhanced U mobilization in the presence of anthropogenic or biogenic ligands. These findings illustrate the complex influence of competing metals and humic substances on U mobilization by anthropogenic and biogenic ligands in the environment.


Asunto(s)
Sustancias Húmicas , Uranio , Uranio/química , Compuestos Férricos , Ligandos , Citratos
18.
J Am Chem Soc ; 144(34): 15672-15679, 2022 08 31.
Artículo en Inglés | MEDLINE | ID: mdl-35993888

RESUMEN

Expanding proton-coupled electron transfer to multiproton translocations (MPCET) provides a bioinspired mechanism to transport protons away from the redox site. This expansion has been accomplished by separating the initial phenolic proton donor from the pyridine-based terminal proton acceptor by a Grotthuss-type proton wire made up of concatenated benzimidazoles that form a hydrogen-bonded network. However, it was found that the midpoint potential of the phenol oxidation that launched the Grotthuss-type proton translocations is a function of the number of benzimidazoles in the hydrogen-bonded network; it becomes less positive (i.e., a weaker oxidant) as the number of bridging benzimidazoles increases. Herein, we report a strategy to maintain the high redox potential necessary for oxidative processes relevant to artificial photosynthesis, e.g., water oxidation and long-range MPCET processes for managing protons. The integrated structural and functional roles of the benzimidazole-based bridge provide sites for substitution of the benzimidazoles with electron-withdrawing groups (e.g., trifluoromethyl groups). Such substitution increases the midpoint potential of the phenoxyl radical/phenol couple so that proton translocations over ∼11 Å become thermodynamically comparable to that of an unsubstituted system where one proton is transferred over ∼2.5 Å. The extended, substituted system maintains the hydrogen-bonded network; infrared spectroelectrochemistry confirms reversible proton translocations from the phenol to the pyridyl terminal proton acceptor upon oxidation and reduction. Theory supports the change in driving force with added electron-withdrawing groups and provides insight into the role of electron density and electrostatic potential in MPCET processes associated with these Grotthuss-type proton translocations.


Asunto(s)
Fenoles , Protones , Bencimidazoles/química , Transporte de Electrón , Hidrógeno/química , Oxidación-Reducción , Fenol/química , Fenoles/química
19.
Opt Express ; 30(19): 34378-34384, 2022 Sep 12.
Artículo en Inglés | MEDLINE | ID: mdl-36242450

RESUMEN

Optical manipulation is interfacing disciplines in the micro and nanoscale, from molecular biology to quantum computation. Versatile solutions for increasingly more sophisticated technological applications require multiple traps with which to maneuver dynamically several particles in three dimensions. The axial direction is usually overlooked due to difficulties in observing particles away from an objective-lens focal plane, a normal element in optical tweezers, and in managing interparticle distances along the trapping beam propagating direction, where strong radiation pressure and shadowing effects compromise the simultaneous and stable confinement of the particles. Here, aperiodic kinoform diffractive lens based on the m-Bonacci sequence are proposed as a new trapping strategy. This lens provides split first-order diffractive foci whose separation depends on the generalized m-golden ratio. We show the extended manipulation capabilities of a laser tweezers system generated by these lens, in which concomitant trapping of particles in different focal planes takes place. Positioning particles in the axial direction with computer-controlled distances allows dynamic three-dimensional all-optical lattices, useful in a variety of microscale and nanoscale applications.

20.
Glob Chang Biol ; 28(9): 3066-3082, 2022 05.
Artículo en Inglés | MEDLINE | ID: mdl-35170154

RESUMEN

Significant gaps remain in understanding the response of plant reproduction to environmental change. This is partly because measuring reproduction in long-lived plants requires direct observation over many years and such datasets have rarely been made publicly available. Here we introduce MASTREE+, a data set that collates reproductive time-series data from across the globe and makes these data freely available to the community. MASTREE+ includes 73,828 georeferenced observations of annual reproduction (e.g. seed and fruit counts) in perennial plant populations worldwide. These observations consist of 5971 population-level time-series from 974 species in 66 countries. The mean and median time-series length is 12.4 and 10 years respectively, and the data set includes 1122 series that extend over at least two decades (≥20 years of observations). For a subset of well-studied species, MASTREE+ includes extensive replication of time-series across geographical and climatic gradients. Here we describe the open-access data set, available as a.csv file, and we introduce an associated web-based app for data exploration. MASTREE+ will provide the basis for improved understanding of the response of long-lived plant reproduction to environmental change. Additionally, MASTREE+ will enable investigation of the ecology and evolution of reproductive strategies in perennial plants, and the role of plant reproduction as a driver of ecosystem dynamics.


Aún existen importantes vacíos en la comprensión de la respuesta reproductiva de las plantas al cambio medioambiental, en parte, porque su monitoreo en especies de plantas longevas requiere una observación directa durante muchos años, y estos conjuntos de datos rara vez han estado disponibles. Aquí presentamos a MASTREE +, una base de datos que recopila series de tiempo de la reproducción de las plantas de todo el planeta, poniendo a disposición estos datos de libre acceso para la comunidad científica. MASTREE + incluye 73.828 puntos de observación de la reproducción anual georreferenciados (ej. conteos de semillas y frutos) en poblaciones de plantas perennes en todo el mundo. Estas observaciones consisten en 5971 series temporales a nivel de población provenientes de 974 especies en 66 países. La mediana de la duración de las series de tiempo es de 10 años (media = 12.4 años) y el conjunto de datos incluye 1.122 series de al menos dos décadas (≥20 años de observaciones). Para un subconjunto de especies bien estudiadas, MASTREE +incluye un amplio conjunto de series temporales replicadas en gradientes geográficos y climáticos. Describimos el conjunto de datos de acceso abierto disponible como un archivo.csv y presentamos una aplicación web asociada para la exploración de datos. MASTREE+ proporcionará la base para mejorar la comprensión sobre la respuesta reproductiva de plantas longevas al cambio medioambiental. Además, MASTREE+ facilitará los avances en la investigación de la ecología y la evolución de las estrategias reproductivas en plantas perennes y el papel de la reproducción vegetal como determinante de la dinámica de ecosistemas.


Asunto(s)
Ecosistema , Reproducción , Ecología , Plantas , Semillas/fisiología
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