The breakup of viscous liquid threads is governed by a complex interplay of inertial, viscous and capillary stresses. Theoretical predictions near the point of breakup suggest the emergence of a finite-time singularity, leading to universal power laws describing the breakup, characterised by a universal prefactor. Recent stability analyses indicate that, due to the presence of complex eigenvalues, achieving similarity may only be possible through time-damped oscillations, making it unclear when and how self-similar regimes are reached for both visco-inertial and viscous regimes. In this paper, we combine experiments with unprecedented spatio-temporal resolution and highly resolved numerical simulations to investigate the evolution of the liquid free surface during the pinching of a viscous capillary bridge. We experimentally show for the first time that, for viscous fluids the approach to the self-similar solution is composed of a large overshoot of the instantaneous shrinking speed before the system converges to the nonlinear pinch-off similarity solution. In the visco-inertial case, the convergence to the stable solution is oscillatory, whereas in the viscous case, the approach to singularity is monotonic. While our experimental and numerical results are in good agreement in the viscous regime, systematic differences emerge in the visco-inertial regime, potentially because of effects such as polymer polydispersity, which are not incorporated into our numerical model.

Group interpersonal therapy (IPT) was introduced to Senegal to treat depression in people living with HIV (PLWH), using a task-shifting approach. Following successful implementation at a tertiary-level hospital in Dakar, we evaluate IPT’s acceptability, feasibility and benefits in primary and secondary-level suburban health facilities. We assess the impact of IPT adaptations and organizational changes and identify sustainability requirements. PLWH with depression received group IPT following the World Health Organization protocol. Acceptability, feasibility and implementation aspects were assessed quantitatively and qualitatively following specific conceptual frameworks. Depressive symptoms severity (PHQ-9) and functioning (WHODAS) were measured pre-, post-treatment and at 3-month follow-up. General linear mixed models were used to describe changes in outcomes over time. Qualitative data were analyzed thematically. Of 84 participants (median age: 45, female>50%), 81 completed group IPT. Enrolment refusal and dropout rates were 7% and 4%. Ninety-seven percent attended at least seven sessions out of eight. Depressive symptoms and functioning significantly improved by therapy’s end (β = 12,2, CI 95% [11.6, 12.8] and β = 8.5, CI 95% [7.3, 9.7], respectively) with gains being sustained 3 months later (p = 0.94 and 0.99, respectively). Adaptations and organizational changes proved successful, but depression screening and diagnosis communication to patients remained challenging. Emerging needs included a tailored patient care pathway and confidentiality. Participants advocated for depression care integration into HIV services. Group IPT’s successful implementation in various ecological and organizational contexts in Senegal indicates high acceptability and feasibility. Sustainability may be enhanced by addressing specific needs at multiple levels (individual, organizational, systemic). A comprehensive reflection on strategies to sustain and scale up group IPT is the next logical step.

Titanium clips (TC) have previously been successfully used for dural repair and closure in spinal surgeries. Meanwhile, minimally invasive spine surgery (MIS) has widely expanded its indications. At our institution, MIS has become the preferred approach for most spine intradural lesions. While the technique has yielded favorable clinical outcomes, we have successfully incorporated the use of TC for dura closure as an alternative to traditional suturing. This technical note outlines the step-by-step application of TC for duroplasty and emphasizes the factors that make their use advantageous in MIS. We present our experience and discuss relevant literature and key nuances.

Clay minerals in chilled or brecciated margins (altered glass) and massive inner crystalline parts (mesostasis) of three basalt-hawaiite bodies from Mururoa Atoll (French Polynesia) have been studied in order to compare their chemical and mineralogical compositions. Polyphase assemblages comprise di- and trioctahedral phases, both of which consist of non-expandable layers (chlorite, celadonite) and two types of expandable layers (saponite and Fe-rich smectite or ‘nontronite-like’ material). The presence of the Fe-rich clays is supported by the presence of the X-ray diffraction 060 peak at 1.51–1.52 Å and of the infrared absorption bands at 875 and 822 cm−1 (Fe3+-Al-OH and Fe3+-Fe3+-OH groups, respectively). The chemical composition of the Fe-rich smectites does not fit with the theoretical nontronite field. The layer charge averages 1 per Si4O10 making these Fe-rich smectites close to ‘celadonite-type’ clays. This could explain the presence of mixed-layer celadonite-smectite. Plotted in an M+/4Si vs. Fe/sum octahedral cations diagram, the chemical compositions of clay minerals in the mesostasis form a continuous field limited by the celadonite-high-charge nontronite-like smectite and chlorite end-members. The clay assemblages are different from those formed in hydrothermal systems or low-grade metamorphic conditions which are characterized by the sequence: saponite → randomly ordered chlorite-smectite mixed-layered minerals (MLMs) → corrensite → chlorite. The systematic presence of Fe-rich clays either in the altered chilled margins or in the massive inner parts of the basalt-hawaiite bodies (high-charge nontronite-like smectite and mixed-layer nontronite-celadonite) makes the Mururoa sea-mount a potential terrestrial analogue for Mars surface exploration.

The clay minerals formed in chilled margins and massive crystallized inner parts of three basalt-hawaiite bodies of Mururoa Atoll (French Polynesia) exhibit contrasting textures. Glass alteration textures are observed around fractures crosscutting the quenched margins: Fe-rich clays grow inward into the glass (retreating surface) while Mg-rich clays grow outward (open space). The textures of clay deposits filling the diktytaxitic voids (mesostasis) in the massive inner parts of the three volcanic bodies are different: unoriented clay matrix with embedded euhedral apatite and pyroxene microcrysts (submarine flow); pallisadic clays coating the void walls and the crystal surfaces of apatite and K-feldspar microcrysts (subaerial flow); and clay muffs covering all the apatite needles, with the central part of the void remaining empty (dike). The unoriented texture could result from the alteration of a glass precursor concomitant with the olivine phenocrysts (clay pseudomorphs). However, such an alteration implies important chemical transfers which are not observed. The pallisadic and muff textures form through heterogeneous nucleation on the solid surfaces and crystal growth from a saline solution. No glass precursor existed. As the center of the diktytaxitic voids in the dike is empty, the residual liquid was probably boiling. The amounts of light rare earth elements (LREE), Sr, and the most incompatible elements are greater in clays from diktytaxitic voids relative to the amounts formed in the altered glass of the chilled margins. Thus, diktytaxitic clays formed from a residual liquid which gave either an evolved glass or a saline solution after cooling (fractionation process). The δ18O variation vs. loss on ignition (LOI) indicates that sea water was involved either in rock alteration or magma contamination. This is confirmed by the 87Rb/86Sr ratio of bulk rocks and clay fractions from the quenched and massive inner parts of the three volcanic bodies which do not fit with the 11.5 Ma isochron indicating that the Rb-Sr system was not closed at any stage during the magmatic history.