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For applications such as spin accumulation sensors for next-generation hard disk drive read heads, and for fundamental research, it is desirable to increase the spin signal in metallic non-local spin valves, which are central devices in spintronics. To this end, here, we report on the integration of high-spin-polarization Co–Fe binary alloy ferromagnetic injectors and detectors in Al-based non-local spin valves. Room-temperature deposition on amorphous substrates from an alloy target is shown to generate smooth, polycrystalline (110-textured), solid-solution body-centered-cubic Co75Fe25 films, which we characterize by energy dispersive x-ray spectroscopy, x-ray diffraction, x-ray reflectivity, atomic force microscopy, and electronic transport. Simple integration into transparent-interface Al non-local spin valves is then shown to realize up to a factor of ∼5 enhancement of the spin signal relative to Co, with full quantitative analysis yielding strikingly temperature-independent current spin polarizations exceeding 60%. We make a detailed quantitative comparison of these values with prior literature, concluding that Co–Fe alloys present a remarkably facile route to higher spin polarization and spin signals in non-local spin valves, with minimal barrier to adoption. 

Animals often communicate in complex, heterogeneous environments, leading to hypothesized selection for increased detectability or discriminability in signaling traits. The extent to which secondary sexual ornaments have evolved to overcome the challenges of signaling in complex environments, however, remains understudied, especially in comparison to their role as indicator traits. This study tested the hypothesis that the condition-dependent secondary sexual ornamentation in the wolf spider Rabidosa rabida functions to increase detectability/discriminability in visually complex environments. We predicted that male ornamentation would interact with the complexity of the signaling environment to affect male mating success. In particular, we expected ornaments to confer a greater mating advantage when males courted in visually complex environments. To test this, we artificially manipulated male foreleg ornamentation (present/absent) and ran repeated-measures mating trials across laboratory microcosms that represented simple versus complex visual signaling environments. Microcosm visual complexity differed in their background pattern, grass stem color, and grass stem placement. We found that ornamented males mated more often and more quickly than unornamented males across both environments, but we found no support for an ornament-by-environment interaction. Male courtship rate, however, did interact with the signaling environment. Despite achieving the same level of mating success across signaling environments, ornamented males courted less rapidly in complex versus simple environments, although environmental complexity had no influence on unornamented male courtship rates. Our results suggest that the visual complexity of the signaling environment influences the interactive influence of ornamentation and dynamic visual courtship on female mate choice.

 

Understanding the fitness consequences of different life histories is critical for explaining their diversity and for predicting effects of changing environmental conditions. However, current theory on plant life histories relies on phenomenological, rather than mechanistic, models of resource production.

We combined a well‐supported mechanistic model of ontogenetic growth that incorporates differences in the size‐dependent scaling of gross resource production and maintenance costs with a dynamic optimization model to predict schedules of reproduction and prolonged dormancy (plants staying below ground for ≥1 growing season) that maximize lifetime offspring production.

Our model makes three novel predictions: First, maintenance costs strongly influence the conditions under which a monocarpic or polycarpic life history evolves and how resources should be allocated to reproduction by polycarpic plants. Second, in contrast to previous theory, our model allows plants to compensate for low survival conditions by allocating a larger proportion of resources to storage and thereby improving overwinter survival. Incorporating this ecological mechanism in the model is critically important because without it our model never predicts significant investment into storage, which is inconsistent with empirical observations. Third, our model predicts that prolonged dormancy may evolve solely in response to resource allocation trade‐offs.

Significance. Our findings reveal that maintenance costs and the effects of resource allocation on survival are primary determinants of the fitness consequences of different life history strategies, yet previous theory on plant life history evolution has largely ignored these factors. Our findings also validate recent arguments that prolonged dormancy may be an optimal response to costs of sprouting. These findings have broad implications for understanding patterns of plant life history variation and predicting plant responses to changing environments.

 

Collection of a blood sample defined by the term “blood liquid biopsy” is commonly used to detect diagnostic, prognostic, and therapeutic decision‐making markers of metastatic tumors including circulating tumor cells (CTCs). Many tumors also release CTCs and other markers into lymph fluid, but the utility of lymphatic markers largely remains unexplored. Here, we introduce lymph liquid biopsy through collection of peripheral (afferent) and central (thoracic duct [TD]) lymph samples and demonstrates its feasibility for detection of stem‐like CTCs potentially responsible for metastasis development and tumor relapse. Stemness of lymphatic CTCs (L‐CTCs) was determined by spheroid‐forming assay in vitro. Simultaneously, we tested blood CTCs by conventional blood liquid biopsy, and monitored the primary tumor size, early metastasis in a sentinel lymph node (SLN) and distant metastasis in lungs. Using a mouse model at early melanoma stage with no distant metastasis, we identified stem‐like L‐CTCs in lymph samples from afferent lymphatic vessels. Since these vessels transport cells from the primary tumor to SLN, our finding emphasizes the significance of the lymphatic pathway in development of SLN metastasis. Surprisingly, in pre‐metastatic disease, stem‐like L‐CTCs were detected in lymph samples from the TD, which directly empties lymph into blood circulation. This suggests a new contribution of the lymphatic system to initiation of distant metastasis. Integration of lymph and blood liquid biopsies demonstrated that all mice with early melanoma had stem‐like CTCs in at least one of three samples (afferent lymph, TD lymph, and blood). At the stage of distant metastasis, spheroid‐forming L‐CTCs were detected in TD lymph, but not in afferent lymph. Altogether, our results demonstrated that lymph liquid biopsy and testing L‐CTCs holds promise for diagnosis and prognosis of early metastasis. © 2020 International Society for Advancement of Cytometry