The geomagnetic field shows aperiodic reversals and excursions separated by stable polarity periods. Although the exact mechanisms responsible of reversals are still debated, several models of ...different complexity have been proposed. Here we use, for the first time, a different and novel approach based on the theory of tipping points to detect and characterize geomagnetic reversals occurred during the period 25–36 millions years ago by using a high‐resolution magnetostratigraphic study conducted on a sedimentary section located on Maud Rise in the Southern Ocean. We detect a critical threshold for an early warning indicator of the occurrence of a polarity reversal below which a polarity reversal starts. Through the proper use of this early warning indicator we build up a simple non‐autonomous stochastic model to describe the main features of polarity reversals. This approach could be helpful for building up a novel framework for paleomagnetic studies.
Plain Language Summary
Geomagnetic polarity reversals involve the complete flip of Earth's magnetic field, and they provide valuable insights into geological and biological processes. Geomagnetic reversals have been extensively studied since they were first proposed in 1906, and paleomagnetic studies indicate that the Earth's magnetic field has undergone multiple polarity reversals over millions of years. The causes of these reversals are still being investigated, but one hypothesis suggests that a complex dynamics of the Earth's liquid outer core plays a key role. We use the concept of tipping points and their theory to identify an early warning signal for the occurrence of polarity reversals and provide a simple model to improve our capabilities of predicting them, also revealing that the timing for a complete reversal is of the order of 5,000 years, which is consistent with previous estimations.
Key Points
A recently‐proposed method based on tipping point theory detects and characterizes geomagnetic reversals from 25 to 36 million years ago
A critical threshold is identified as an early warning indicator of polarity reversal occurrence
A simple non‐autonomous model is proposed to describe polarity reversals
PuffinPlot is a program for paleomagnetic data analysis and plotting, first released in 2012 and under continuous development since then. It is free, cross‐platform software and provides both a ...graphical desktop interface for interactive use and an application‐programmer interface for scripting. We present a major new release of the program, describe significant new features added since the first release, and demonstrate their application to real‐world data. New features include automatic magnetic declination realignment, relative paleointensity calculation, virtual geomagnetic pole determination, calculation of inclination‐only statistics, support for reproducible research via the export of self‐contained data bundles, and support for reading a number of popular paleomagnetic file formats. We also discuss the application of unit tests in ensuring PuffinPlot's long‐term reliability and outline directions for future development of the software.
Plain Language Summary
By analyzing the remanent magnetization of ancient rocks and sediments, we can work out the strength and direction of the Earth's magnetic field when they were formed. We do this with laboratory measurements of the magnetic properties of rock samples or sediment cores, combined with treatments to remove any unwanted magnetic signals from them. PuffinPlot is a program which analyses these laboratory measurements to estimate the original magnetic field. In this paper we present a new release of PuffinPlot and describe and demonstrate some of its new features. These include a way to calculate magnetic field directions even when a sediment core has been rotated or when it has no azimuthal orientation, combining multiple measurements to estimate the strength of the original magnetic field, and generating a self‐contained software and data package to let other researchers verify and redo the analysis automatically. We also discuss automated tests which make the software more reliable and features that we plan to include in future releases.
Key Points
PuffinPlot is a popular application for paleomagnetic data analysis
We document a number of significant features added since the initial release in 2012
Features include declination realignment, VGP and RPI calculation, and data bundle export
Cisplatin and other platinum(II) analogs are widely used in clinical practice as anti-cancer drugs for a wide range of tumors. The primary mechanism by which they exert their action is through the ...formation of adducts with genomic DNA. However, multiple cellular targets by platinum(II) complexes have been described. In particular, the early events occurring at the plasma membrane (PM), i.e., platinum-membrane interactions seem to be involved in the uptake, cytotoxicity and cell-resistance to cisplatin. In fact, PM influences signaling events, and cisplatin-induced changes on membrane organization and fluidity were shown to activate apoptotic pathways. This review critically discusses the sequence of events caused by lipid membrane-platinum interactions, with emphasis on the mechanisms that lead to changes in the biophysical properties of the membranes (e.g., fluidity and permeability), and how these correlate with sensitivity and resistance phenotypes of cells to platinum(II) complexes.
The field of nanomedicine has significantly influenced research areas such as drug delivery, diagnostics, theranostics, and regenerative medicine; however, the further development of this field will ...face significant challenges at the regulatory level if related guidance remains unclear and unconsolidated. This review describes those features and pathways crucial to the clinical translation of nanomedicine and highlights considerations for early-stage product development. These include identifying those critical quality attributes of the drug product essential for activity and safety, appropriate analytical methods (physical, chemical, biological) for characterization, important process parameters, and adequate pre-clinical models. Additional concerns include the evaluation of batch-to-batch consistency and considerations regarding scaling up that will ensure a successful reproducible manufacturing process. Furthermore, we advise close collaboration with regulatory agencies from the early stages of development to assure an aligned position to accelerate the development of future nanomedicines.
Graphical abstract
Research on global ice-volume changes during Pleistocene glacial cycles is hindered by a lack of detailed sea-level records for time intervals older than the last interglacial. Here we present the ...first robustly dated, continuous and highly resolved records of Red Sea sea level and rates of sea-level change over the last 500,000 years, based on tight synchronization to an Asian monsoon record. We observe maximum 'natural' (pre-anthropogenic forcing) sea-level rise rates below 2 m per century following periods with up to twice present-day ice volumes, and substantially higher rise rates for greater ice volumes. We also find that maximum sea-level rise rates were attained within 2 kyr of the onset of deglaciations, for 85% of such events. Finally, multivariate regressions of orbital parameters, sea-level and monsoon records suggest that major meltwater pulses account for millennial-scale variability and insolation-lagged responses in Asian monsoon records.
Abstract
We present a geological-stratigraphical study aimed to provide chronologic constraints to the sea-level markers occurring at two coastal caves of central Italy (Grotta Guattari and Grotta ...dei Moscerini) and to the Neanderthal frequentation of these caves, in the light of recent archaeological and geomorphological-geochronological studies suggesting similar sea levels during MIS 5.5 and MIS 5.3, and only few m below the Present during MIS 5.1 in this region. Based on the review of previous literature data, combined with new stratigraphic observations at Grotta Guattari and re-analysis of archive material including unpublished field notes from Grotta dei Moscerini, we reconstruct a plausible sea-level history accounting for the lithological and paleoenvironmental features of their sedimentary fillings. In particular, we outline the abundant occurrence of well-rounded pumice clasts within the sedimentary deposits of Moscerini Cave, attesting for the proximity to the beach where this pumice was gathered by wave action. Through the petrographic and geochemical analysis of this pumice we evidence provenance from Phlegraean Fields and Ischia Island volcanic districts, framing their chronology in the time span 118–40 ka, consistent with literature ESR-U/Th dates providing ages ranging 101 ± 5–74 ± 7 ka for the sedimentary filling of both Moscerini and Guattari caves.
Ar/
Ar geochronology constraints to aggradational phases and grain size variations show that the two large gravel beds occurring in the sedimentary filling of the Liri fluvial-lacustrine basin ...(central Italy) recorded the occurrence of deglaciation events synchronous within uncertainties with global meltwater pulses at ca. 450 and 350 ka. In particular, we find a precise match between the ages of gravel deposition and the occurrence of moderate sea-level rise events which anticipate those more marked during the glacial termination V and IV in the Red Sea relative sea level curve, as already verified by data from the Tiber River catchment basin. Such correspondence suggests that gravel deposition is facilitated by melting of Apennine mountain range glaciers, which provide the water transport energy and a surplus of clastic input to the rivers draining the mountain regions and flowing into the Tyrrhenian Sea. Therefore, the thick gravel beds intercalated in the sedimentary filling of the catchment basins of the major rivers in central Italy may be regarded as an equivalent proxy of large deglaciation events, similar to the ice-rafted debris in northern Atlantic. Consistent with this hypothesis, we also show the close correspondence between the occurrence of particularly mild (warmer) minima of the mean summer insolation at 65° N and these early aggradational phases, as well as with other anomalous early sea-level rises occurring c. 750 ka and 540 ka at the onset of glacial termination VIII and VI, and 40 ka at the onset of the so-called Heinrich events.
Cancer is one of the most common diseases afflicting people globally. New therapeutic approaches are needed due to the complexity of cancer as a disease. Many current treatments are very toxic and ...have modest efficacy at best. Increased understanding of tumor biology and immunology has allowed the development of specific immunotherapies with minimal toxicity. It is important to highlight the performance of monoclonal antibodies, immune adjuvants, vaccines and cell-based treatments. Although these approaches have shown varying degrees of clinical efficacy, they illustrate the potential to develop new strategies. Targeted immunotherapy is being explored to overcome the heterogeneity of malignant cells and the immune suppression induced by both the tumor and its microenvironment. Nanodelivery strategies seek to minimize systemic exposure to target therapy to malignant tissue and cells. Intracellular penetration has been examined through the use of functionalized particulates. These nano-particulate associated medicines are being developed for use in imaging, diagnostics and cancer targeting. Although nano-particulates are inherently complex medicines, the ability to confer, at least in principle, different types of functionality allows for the plausible consideration these nanodelivery strategies can be exploited for use as combination medicines. The development of targeted nanodelivery systems in which therapeutic and imaging agents are merged into a single platform is an attractive strategy. Currently, several nanoplatform-based formulations, such as polymeric nanoparticles, micelles, liposomes and dendrimers are in preclinical and clinical stages of development. Herein, nanodelivery strategies presently investigated for cancer immunotherapy, cancer targeting mechanisms and nanocarrier functionalization methods will be described. We also intend to discuss the emerging nano-based approaches suitable to be used as imaging techniques and as cancer treatment options.
Constraining the long‐term variability and average of the Earth's magnetic field strength is fundamental to understanding the characteristics and behavior of the geomagnetic field. Questions remain ...about the strength of the average field, and the relationship between strength and reversal frequency, due to the dispersion of data from key time intervals. Here, we focus on the Cretaceous Normal Superchron (CNS; 121‐84 Ma), during which there were no reversals. We present new intensity results from 41 submarine basaltic glass (SBG) sites collected on the Nicoya Peninsula and Murcièlago Islands, Costa Rica. New and revised 40Ar/39Ar and biostratigraphic age constraints from previous studies indicate ages from 141 to 65 Ma. One site with an age of 135.1 ± 1.5 Ma (2σ) gave a reliable intensity result of 34 ± 8 µT (equivalent to a virtual axial dipole moment, VADM, value of 88 ± 20 ZAm2), three sites from 121 to 112 Ma, spanning the onset of the CNS, vary from 21 ± 1 to 34 ± 4 µT (53 ± 3 to 87 ± 10 ZAm2). These results from the CNS are all higher than the long‐term average of ∼42 ZAm2 and data from Suhongtu, Mongolia (46–53 ZAm2) and are similar to the Troodos Ophiolite, Cyprus (81 ZAm2, reinterpreted in this study). Together with the reinterpreted data, the new Costa Rica results suggest that the strength of the geomagnetic field was approximately the same both before and after the onset of the CNS. Therefore, the data do not support a strict correlation between polarity interval length and the strength of the magnetic field.
Plain Language Summary
Understanding the Earth's magnetic field behavior in the past is important to validate geodynamo simulations. However, because of the paucity of available data, it is poorly understood. In particular, it has been argued that the strength of the Earth's magnetic field, or paleointensity, was correlated with the stability of the field, where a strong field was less prone to magnetic reversals than a weak field. Hence, we have investigated the anomalously long period of stability, the Cretaceous Normal Superchron (CNS) during which no magnetic reversals occurred. Our new data from Costa Rican basaltic glasses, together with reinterpreted data from Inner Mongolia and the Troodos Ophiolite in Cyprus, suggest that the magnetic field during the CNS was similar to the present‐day field and these high values are nearly twice the long‐term average value for the last 200 Ma. However, high field values were also detected in the period prior to the onset of the CNS, hence our data do not support a strict correlation between strength and stability of the Earth's magnetic field.
Key Points
The Cretaceous Normal Superchron (CNS) is key to understanding geomagnetic field behavior
We present new paleointensity data from Costa Rica over an age range of 135–112 Ma, spanning the onset of the CNS
We find that field strength was high both prior and during the early CNS, which does not support a correlation between field strength and stability
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