Our understanding of the past behavior of the geomagnetic field arises from magnetic signals stored in geological materials, e.g., (volcanic) rocks. Bulk rock samples, however, often contain magnetic ...grains that differ in chemistry, size, and shape; some of them record the Earth's magnetic field well, others are unreliable. The presence of a small amount of adverse behaved magnetic grains in a sample may already obscure important information on the past state of the geomagnetic field. Recently it was shown that it is possible to determine magnetizations of individual grains in a sample by combining X‐ray computed tomography and magnetic surface scanning measurements. Here we establish this new Micromagnetic Tomography (MMT) technique and make it suitable for use with different magnetic scanning techniques, and for both synthetic and natural samples. We acquired reliable magnetic directions by selecting subsets of grains in a synthetic sample, and we obtained rock‐magnetic information of individual grains in a volcanic sample. This illustrates that MMT opens up entirely new venues of paleomagnetic and rock‐magnetic research. MMT's unique ability to determine the magnetization of individual grains in a nondestructive way allows for a systematic analysis of how geological materials record and retain information on the past state of the Earth's magnetic field. Moreover, by interpreting only the contributions of known magnetically well‐behaved grains in a sample, MMT has the potential to unlock paleomagnetic information from even the most complex, crucial, or valuable recorders that current methods are unable to recover.
Plain Language Summary
Our understanding of the past behavior of the Earth's magnetic field relies on our ability to interpret magnetic signals from rocks. Currently, we measure bulk samples consisting of many magnetic grains at once. Not all magnetic grains are good recorders of the geomagnetic field. The presence of even small amounts of adverse behaved grains in a sample already obscures vital information about the Earth's magnetic field. Here we present and establish a new method that determines magnetizations of individual grains in a sample: Micromagnetic Tomography. This new and exciting method allows to select and interpret only magnetizations of grains that are known good recorders in a sample. This will unlock magnetic information from even the most complex, crucial, or valuable samples that current methods are unable to recover.
Key Points
Micromagnetic Tomography enables determining, selecting, and interpreting magnetizations of individual grains in a sample
We obtained magnetic directions and rock‐magnetic information from subsets of grains in both a synthetic and a natural sample
Micromagnetic Tomography has the potential to unlock magnetic information from even the most complex recorders that currently goes obscured
Anthropogenic stressors are exacerbating the emergence and spread of pathogens worldwide. In regions like the Arctic, where ecosystems are particularly susceptible, marked changes are predicted in ...regional diversity, intensity, and patterns of infectious diseases. To understand such rapidly changing host‐pathogen dynamics and mitigate the impacts of novel pathogens, we need sensitive disease surveillance tools. We developed and validated a novel multiplexed, magnetic capture, and ddPCR tool for the surveillance of multiple pathogens in polar bears, a sentinel species that is considered susceptible to climate change and other stressors with a pan‐Arctic distribution. Through sequence‐specific magnetic capture, we concentrated five target template sequences from three zoonotic bacteria (Erysipelothrix rhusiopathiae, Francisella tularensis, and Mycobacterium tuberculosis complex) and two parasitic (Toxoplasma gondii and Trichinella spp.) pathogens from large quantities (<100 g) of host tissue. We then designed and validated two multiplexed probe‐based ddPCR assays for the amplification and detection of the low‐concentration target DNA. Validations used 48 polar bear tissues (muscle and liver). We detected 14, 1, 3, 4, and 22 tissue positives for E. rhusiopathiae, F. tularensis, M. tuberculosis complex, T. gondii, and Trichinella spp., respectively. These multiplexed assays offer a rapid, specific tool for quantifying and monitoring the changing geographical and host distributions of pathogens relevant to human and animal health.
Climate change is altering the distributions of many species, including pathogens and their hosts. We have developed new magnetic capture and multiplexed digital droplet PCR assays to detect the presence of three bacterial pathogens and two parasites in polar bear tissues from across the Canadian Arctic. We validate our assays and suggest how these new powerful assays can meaningfully contribute to community‐based monitoring of pathogens in polar bears and other wildlife.
The AD 1761 eruption on Terceira was the only historical subaerial event on the island and one of the last recorded in the Azores. The eruption occurred along the fissure zone that crosses the island ...and produced a trachybasalt lava flow and scoria cones. Small comenditic trachyte lava domes (known as Mistérios Negros) were also thought by some to have formed simultaneously on the eastern flank of Santa Bárbara Volcano. Following a multidisciplinary approach, we combined geological mapping, paleomagnetic, petrographic, mineral and whole-rock geochemical and structural analyses to study this eruption. The paleomagnetic dating method compared geomagnetic vectors (directions and intensities) recorded by both the AD 1761 lava flow and Mistérios Negros domes and revealed that the two events were indeed coeval. Based on new data and interpretation of historical records, we have accordingly reconstructed the AD 1761 eruptive dynamics and distinguished three phases: (1) a precursory phase characterized by decreased degassing in the fumarolic field of Pico Alto Volcano and a gradual increase of seismic activity, which marked the intrusion of trachybasalt magma; (2) a first eruptive phase that started with phreatic explosions on the eastern flank of Santa Bárbara Volcano, followed by the inconspicuous effusion of comenditic trachyte (66 wt% SiO
2
), forming a WNW-ESE-oriented chain of lava domes; and (3) a second eruptive phase on the central part of the fissure zone, where a Hawaiian to Strombolian-style eruption formed small scoria cones (E-W to ENE-WSW-oriented) and a trachybasalt lava flow (50 wt% SiO
2
) which buried 27 houses in Biscoitos village. Petrological analyses show that the two batches of magma were emitted independently without evidence of interaction. We envisage that the dome-forming event was triggered by local stress changes induced by intrusion of the trachybasalt dyke along the fissure zone, which created tensile stress conditions that promoted ascent of comenditic trachyte magma stored beneath Santa Bárbara Volcano.
The most recent diagnostic criteria for multiple sclerosis (MS) ascertain that findings from spinal cord MRI can be used to demonstrate dissemination in space. Because little is known about the ...prevalence and characteristics of cord lesions early in the disease, the authors studied the prevalence of spinal cord abnormalities in patients with early-stage MS and assessed their impact on diagnostic classification.
The brains and spinal cords of 104 recently diagnosed patients with MS were examined. Median interval between first symptom and diagnosis was 18.4 months. The brain MRI protocol included before and after gadolinium axial T1-weighted conventional spin-echo sequences and dual-echo spin-echo images. For spinal cord MRI, sagittal cardiac-triggered dual-echo T2-weighted and sagittal T1-weighted spin-echo images were included. Clinical assessment for each patient included age, sex, clinical signs for spinal cord involvement, and Expanded Disability Status Scale.
Abnormal cord MRIs were found in 83% of patients, usually with only focal lesions. Diffuse cord abnormalities were found in 13% of patients, although in isolation they were found in only three patients. Focal cord lesions were often multiple (median number, 3.0), small (median, 0.8 vertebral segments), and primarily (56.4%) situated in the cervical spinal cord. In 68 of 104 patients (65.4%), two or more focal lesions were visible on spinal cord images. The criteria for dissemination in space, as defined in the McDonald criteria for the brain, were met in only 66.3% of the patients. This percentage increased to 84.6% when spinal cord MRI abnormalities were also included.
Spinal cord abnormalities are prevalent in patients with early-stage MS, have distinct morphologic characteristics, and help to determine dissemination in space at time of diagnosis.
Purpose
Corneal and bulbar conjunctival tumors can be visualized and measured by Anterior Segment Optical Coherence Tomography (A‐OCT) and Ultrasound Biomicroscopy (UBM). We compared tumor depth ...measured by histopathology (HP) with measurements by UBM and A‐OCT to investigate whether the two techniques are as accurate as HP.
Methods
35 patients with 42 corneal or conjunctival bulbar tumors were imaged with A‐OCT and UBM. 11 of the tumors were excised and analyzed on histopathology. The correlation of the depth measurements on HP versus A‐OCT and UBM was statistically analyzed. When the tumor was not excised, depth measurements on A‐OCT versus UBM were compared.
Results
Statistical analysis showed that UBM and HP measurements of tumor depth are positively correlated, as are UBM and A‐OCT measurements. It was not possible to obtain statistically significant data for the correlation between HP and A‐OCT measurements because of the small study population. Image quality was overall better with A‐OCT than with UBM, but in 12 tumors, depth measurement on A‐OCT was impossible because of tumor shadowing (thick or highly pigmented tumor).
Conclusions
UBM can measure tumor depth as accurately as HP. Tumor depth measurements on A‐OCT and UBM are positively correlated. A larger study is needed to investigate whether measurement of tumor depth with A‐OCT is as accurate as HP. Because of drawbacks of depth measurements on histopathology, we believe that A‐OCT and UBM could become the golden standard for measuring corneal and bulbar conjunctival tumor depth. We advise to use A‐OCT if the tumor is not too thick or too pigmented, and to use UBM in case of posterior tumor shadowing on OCT.
The relation between salt marsh accretion and flooding regime was quantified by statistical analysis of a unique dataset of accretion measurements using sedimentation-erosion bars, on three barrier ...islands in the Dutch Wadden Sea over a period of c. 15 years. On one of the islands, natural gas extraction caused deep soil subsidence, which resulted in gradually increasing flooding frequency, duration, and depth, and can thus be seen as a proxy for sea-level rise. Special attention was paid to effects of small-scale variation e.g., in distance to tidal creeks or marsh edges, elevation of the marsh surface, and presence of livestock. Overall mean accretion rate was 0.44 ± 0.0005 cm year
−1
, which significantly exceeded the local rate of sea-level rise of 0.25 ± 0.009 cm year
−1
. A multiple regression approach was used to detect the combined effect of flooding regime and the local environment. The most important flooding-related factors that enhance accretion are mean water depth during flooding and overall mean water depth, but local accretion strongly decreases with increasing distance to the nearest creek or to the salt marsh edge. Mean water depth during flooding can be seen as an indicator for storm intensity, while overall mean water depth is a better indicator for storm frequency. The regression parameters were used to run a simple model simulating the effect of various sea-level scenarios on accretion and show that, even under extreme scenarios of sea-level rise, these salt marshes can probably persist for the next 100 years, although the higher parts may experience more frequent inundation.
Oligochaetes (Annelida) are active bioturbators that can be present in high densities in the transition zone between intertidal flats and salt marshes, though their occurrence and functional role ...remain understudied. This study aimed to clarify the biogeomorphic role of oligochaete bioturbation in facilitating or hindering vegetation establishment. Two microcosm experiments were performed to assess the effect of oligochaete bioturbation on sediment properties, oxidation depth, algal biomass, seed distribution, and germination success of pioneer species Salicornia spp. Oligochaetes created burrow networks in the sediment matrix, which, together with upward conveyor belt feeding, lead to substrate mixing. Sediment reworking rates of oligochaetes were compared with those of polychaete macrofauna. Bioturbation and bio‐irrigation of burrows can stimulate resource flows into the sediment. Oxidation depth increased almost tenfold in the presence of oligochaetes. Their bioturbation did not seem to affect sediment properties such as dry bulk density, porosity, and organic matter content. Sediment reworking, however, significantly reduced algal biomass at the surface with possible cascading effects on sediment stability and erodibility. Oligochaete conveyor belt feeding buried Salicornia spp. seeds until below the critical germination depth, thus negatively affecting Salicornia spp. germination and seedling establishment. Our study indicates that small, though numerous, oligochaete bioturbators may reduce lateral expansion potential of salt marshes by hindering the establishment of pioneer vegetation in the transition zone. Additionally, in dynamic fine‐grained habitats, these oligochaetes have the feature to quickly oxygenate the sediment top layer.
Purpose of the Study: To describe the differential diagnosis and management of a rare conjunctival malignancy. Procedures: A 79-year-old man presented with a conjunctival mass at the limbus. ...Excisional biopsy revealed a malignant mesenchymal tumor with myogenic differentiation. Six months later, three suspect lesions developed at the border of the previous excision. Pathological diagnosis pointed to a leiomyosarcoma. Adjuvant radiotherapy with strontium-90 brachytherapy was applied. After 3 years, there was neither recurrence nor distant metastases. A literature review revealed 11 cases of conjunctival leiomyosarcoma. Results: All 12 cases seemed to originate at the limbal conjunctiva. Scleral invasion was found only in one patient with multiple previous resections. Corneal invasion was reported in two patients. Four patients had a globe-sparing resection. In two of them, margins were not tumor free and additional brachytherapy gave a tumor-free follow-up of 1 and 3 years. Four cases underwent an exenteration. Conclusion and Message: Primary conjunctival leiomyosarcoma is a rare tumor with a favorable prognosis due to early detection and consequently limited size. Diagnosis involves histopathological investigation including immunohistochemistry. If possible, complete resection has the best prognosis. Adjunctive radiotherapy can be effective when the margins are not free and should be considered.
The Frisian islands (Southern North Sea) have extensive island tails, i.e. the entire downdrift side of an island consisting of salt marshes, dunes, beaches and beach plains, and green beaches. ...Currently, large parts of these tails are ageing and losing dynamics, partly due to human influence. This may mean a loss of young stages on the long term, and current management is not enough to counteract this. To aid the development of new interventions aiming at (re)introducing natural dynamics, a conceptual model of island-tail development under natural and disturbed conditions was developed, based on existing data, field visits and literature. The development of an island tail follows the general pattern of biogeomorphic succession. The first phase consists of a bare beach plain. In the second phase, embryonic dunes form. In the third phase, green beaches, dunes and salt marshes form, including drainage by creeks and washovers. In the fourth phase, vegetation succession continues and the morphology stabilises. Human interference (such as sand dikes and embankments) reduces natural dynamics and increases succession speed, leading to a reduction in the diversity in landforms and vegetation types. Both for natural and human-influenced island tails, succession is the dominant process and large-scale rejuvenation only occurs spontaneously when large-scale processes cause erosion or sedimentation. Island tails cannot be kept permanently in a young successional stage by reintroducing natural dynamics through management interventions, as biogeomorphic succession is dominant. However, such interventions may result in local and temporal rejuvenation when tailored to the specific situation.
Background: Many persons with multiple sclerosis (PwMS) report increased fatigue in the afternoon and evening compared with the morning. It is commonly accepted that physical capacity also decreases ...as time of day progresses, potentially influencing the outcomes of testing.
Objective: The objective of this article was to determine whether self-reported fatigue level and walking capacity are influenced by time of day in PwMS.
Methods: A total of 102 PwMS from 8 centers in 5 countries, with a diverse level of ambulatory dysfunction (Expanded Disability Status Scale EDSS <6.5), participated. Patients performed walking capacity tests and reported fatigue level at three different time points (morning, noon, afternoon) during 1 day. Walking capacity was measured with the 6-Minute Walk Test (6MWT) and the 10-m walk test performed at usual and fastest speed. Self-reported fatigue was measured by the Rochester Fatigue Diary (RFD). Subgroups with mild (EDSS 1.5–4.0, n = 53) and moderate (EDSS 4.5–6.5, n = 49) ambulatory dysfunction were formed, as changes during the day were hypothesized to depend on disability status.
Results: Subgroups had different degree of ambulatory dysfunction (p < 0.001) but reported similar fatigue levels. Although RFD scores were affected by time of day with significant differences between morning and noon/afternoon (p < 0.0001), no changes in walking capacity were found in any subgroup. Additional analyses on subgroups distinguished by diurnal change in self-reported fatigue failed to reveal analogous changes in walking capacity.
Conclusions: Testing of walking capacity is unaffected by time of day, despite changes in subjective fatigue.
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