Complete Collapse Research Articles

A test on fire-induced damage of concrete with multiple parameters analysis—Based on tunnel linings of China

Fires in highway tunnels will have a significant impact on the structural performance of lining materials. A ablation test was conducted on 288 concrete specimens (1500 ×1500 ×1500 mm) with four commonly used grades of C20, C25, C30, and C35 at temperature levels of 300 ℃, 600 ℃, 750 ℃, and 900 ℃ for constant periods of 1 h, 2 h, and 4 h. The experiment revealed that: (1) From low to high temperatures, the specimens experienced cracking, spalling, explosion and eventually complete collapse; all grades of concrete remained intact or mostly intact at 600 ℃ but suffered varying degrees of damage above 750 ℃. (2) At the same fire temperature, the damage rate increased linearly with longer ablation time; while at the same ablation time, the damage rate increased quadratically with higher fire temperature. (3) The ultrasonic wave velocity ratio decreased exponentially as the ablation time increased; higher fire temperatures resulted in lower wave velocity ratios within the same ablation time period and there was a turning point at a two-hour ablation time where specimen integrity was lost. (4) For concrete specimens of the same grade and under identical exposure times to fire, as the fire temperature increased,the rate of compressive strength reduction accelerated significantly; sudden drops in compressive strength occurred at temperatures of 600 °C，750 °C，and900°C,and there was a turning point for compressive strength reduction loss after one hour's ablation to fire.(5) When subjected to high ablation temperatures,the decrease rate in concrete strength exceeded that in wave velocity,and changes in strength were more sensitive than changes in wave velocity.

Oliguria caused by dehydration in combat trauma (case series)

Background. A combat gunshot wound is significantly different from a civilian trauma. It is characterized by the prevalence of penetrating injuries, which increases the volume of blood loss at the pre-hospital stage, and the destruction of large masses of muscle tissue (rhabdomyolysis), which leads to acute kidney injury. Moreover, combat trauma occurs in conditions of chronic background stress as a result of severe emotional and physical strain, uncomfortable weather conditions, and deprivation of sleep, drinking and food. So, such a phenomenon as voluntary dehydration is common among soldiers in combat conditions. In wounded, oliguria is often considered a result of acute kidney injury, but it can also be a symptom of severe dehydration. The purpose of our work was to analyze three clinical cases of oliguria caused by dehydration in wounded with combat trauma to better understand the severity of the condition of such victims and to improve medical aid for them. Materials and methods. The article describes three cases of men aged 35, 50 and 44 years with combat gunshot wounds to the extremities, who were admitted to the tertiary care hospital on the second day after the injury with oliguria (0.18–0.19 ml/kg/hr) and high creatinine (333 to 457 μmol/L). Results. All three patients were conscious, breathing spontaneously, had stable hemodynamics, and moderate anemia after pre-hospital blood transfusions. Focused ultrasound study revealed hyperdynamic left ventricle and small inferior vena cava with complete inspiratory collapse, which suggested hypovolemia. Upon further investigation of the medical history, patients admitted not drinking any liquid for one to two days prior to injury. Tissue hydrophilicity test was conducted which showed severe dehydration in all three cases. Infusion volume was calculated using P.I. Shelestiuk nomogram (modified by O.V. Kravets et al.) and amounted to 60 ml/kg of balanced crystalloid solutions. Upon starting rehydration, diuresis was restored within two hours and amounted to 0.7–2.1 ml/kg/h in all three patients. Creatinine levels normalized in 2–4 days. Patients were transferred to another hospital in a moderate condition in 4–5 days. Conclusions. Oliguria is a frequent complication of combat gunshot injury. Although it is most often associated with acute kidney injury from rhabdomyolysis, it should also be considered that in a combat environment, soldiers’ access to water may be limited and the injury may be accompanied by dehydration. In the cases presented, the differential diagnosis of the causes of oliguria in the wounded made it possible to detect signs of severe dehydration, abstain from the inappropriate use of saluretics, quickly compensate for the fluid deficit, and to avoid the development of kidney damage and the need for renal replacement therapy.

Chemical inactivation of two non-enveloped viruses results in distinct thermal unfolding patterns and morphological alterations

BackgroundNon-enveloped viruses, which lack a lipid envelope, display higher resistance to disinfectants, soaps and sanitizers compared to enveloped viruses. The capsids of these viruses are highly stable and symmetric protein shells that resist inactivation by commonly employed virucidal agents. This group of viruses include highly transmissible human pathogens such as Rotavirus, Poliovirus, Foot and Mouth Disease Virus, Norovirus and Adenovirus; thus, devising appropriate strategies for chemical disinfection is essential.ResultsIn this study, we tested a mild, hypoallergenic combination of a denaturant, alcohol, and organic acid (3.2% citric acid, 1% urea and 70% ethanol, pH4) on two representative non-enveloped viruses – Human Adenovirus 5 (HAdV5) and Feline Calicivirus (FCV)– and evaluated the pathways of capsid neutralization using biophysical methods. The conformational shifts in the capsid upon chemical treatment were studied using Differential Scanning Calorimetry (DSC), while the morphological alterations were visualized concurrently using Transmission Electron Microscopy (TEM). We found that while treatment of purified HAdV5 particles with a formulation resulted in thermal instability and, large scale aggregation; similar treatment of FCV particles resulted in complete collapse of the capsids. Further, while individual components of the formulation caused significant damage to the capsids, a synergistic action of the whole formulation was evident against both non-enveloped viruses tested.ConclusionsThe distinct effects of the chemical treatment on the morphology of HAdV5 and FCV suggests that non-enveloped viruses with icosahedral geometry can follow different morphological pathways to inactivation. Synergistic effect of whole formulation is more effective compared to individual components. Molecular level understanding of inactivation pathways may result in the design and development of effective mass-market formulations for rapid neutralization of non-enveloped viruses.

Sex Differences in Obstructive Patterns on Drug-Induced Sleep Endoscopy.

To identify and characterize sex differences in collapse patterns on drug-induced sleep endoscopy (DISE) in patients with obstructive sleep apnea (OSA). Retrospective cohort analysis. An outpatient tertiary care academic medical center. A retrospective cohort study at a single tertiary care institution was performed from 2020 to 2023. All adult patients who underwent a DISE were included in this study. Univariate and multivariate analyses were used to compare differences between males and females on DISE. 117 patients who underwent DISE were included in this study, including 30% females (n = 35). The average age was 54.7 years (SD 15.2), mean BMI was 28.6 kg/m2 (SD 4.1), and mean apnea-hypopnea index (AHI) was 32.3 events per hour (SD 21.3). Most patients had severe OSA (48.7%). There was no difference in palatine or lingual tonsil size between sexes. On DISE, a significantly lower proportion of females demonstrated complete oropharyngeal lateral wall collapse (25.7% females vs 51.2% males, P = .008). Multivariate analysis revealed that male sex was independently associated with the presence of complete collapse at the oropharynx (odds ratio [OR] 2.55, 95% confidence interval [CI] [0.005-1.868], P = .048) but not at other levels. Additionally, higher BMI was associated with any collapse (partial or complete) at the oropharynx (OR 1.30, 95% CI [0.131-0.392], P < .001). This study demonstrates that a lower proportion of females have complete oropharyngeal lateral wall collapse even when controlling for BMI and AHI. Additional studies are needed to better understand the differences in OSA physiology between the sexes.

7762 A Unique Case Of Sepsis-Driven Bilateral Adrenal Hemorrhages In A Patient With HIT

Abstract Disclosure: A. Siddiqui: None. B. Shalit: None. H. Nadeem: None. Z. Khan: None. D. Pinkhasova: None. Introduction: Bilateral adrenal hemorrhages, commonly seen in the setting of sepsis as Waterhouse Friderichsen syndrome, is a rare life-threatening condition. This process is driven by the release of bacterial endotoxins leading to the activation of coagulation, fibrinolysis, and proinflammatory pathways. It is by a similar process that now non-septic hypercoagulable states, including heparin-induced thrombocytopenia (HIT), factor V Leiden and protein C resistance are also being recognized as etiologic for bilateral adrenal hemorrhaging. The following case demonstrates a combination of the two etiologies leading to adrenal insufficiency from bilateral adrenal hemorrhages. Clinical Case: A 48-year-old male presented to the emergency department with right upper quadrant pain, dyspnea, and a low-grade fever. Laboratory results indicated leukocytosis with a predominance of neutrophils. Initial computed tomography imaging revealed a 4 x 3.5 cm right lower lobe multi-loculated lung abscess and multiple right lower lobe segmental/subsegmental pulmonary emboli. The patient was started on a heparin drip and empiric antibiotics. Infectious disease was consulted to help determine the etiology of the lung abscess. Extensive workup including sputum, blood, fungal cultures, and acid-fast bacillus smear testing were negative. The patient improved on routine broad-spectrum antibiotics and was planned to be transitioned to a direct oral anticoagulant until serial imaging revealed incidental bilateral 4 cm adrenal hemorrhages. Endocrinology was emergently consulted; a random cortisol level was drawn and found to be low at 2.7 (3-17 µg/dL) with an elevated Adrenocorticotropic hormone (ACTH) level of 114 (6 - 50 pg/mL) indicative of primary adrenal insufficiency. The patient subsequently became hypotensive and was started on stress-dose steroids. Upon further investigation, the patient was found to be thrombocytopenic, and hematology was involved. Based on his 4T score of 5, concern was raised for HIT and argatroban was initiated. Moreover, the patient was eventually stabilized for discharge with close follow-ups with endocrinology, infectious disease, and hematology as an outpatient. Conclusion: There have been 17 reported cases of bilateral adrenal hemorrhaging in the setting of HIT uniformly presenting with complete hemodynamic collapse. This case serves as even more unique given the added component of sepsis. Both sepsis and HIT respectively have been well established to pose individual risk for developing bilateral adrenal hemorrhages. Hence, we hope to highlight the importance of exploring all potential causes of adrenal insufficiency in the setting of bilateral adrenal hemorrhaging and emphasize the harms of anchoring to a single etiology. Presentation: 6/3/2024

Implementing a Streamlined Hypoglossal Nerve Stimulator Pathway: Cost, Time to Surgery, and Outcomes.

To evaluate the costs, time to surgery, and clinical outcomes associated with implementing a streamlined hypoglossal nerve stimulator (HGNS) implantation pathway. Retrospective cohort study. Single tertiary care center in the United States from 2016 to 2023. Patients with a lack of complete concentric collapse of the velum during volitional snore on in-office laryngoscopy qualified for the streamlined HGNS pathway. This pathway consisted of confirmatory drug-induced sleep endoscopy (DISE) followed immediately by HGNS implantation during the same surgical encounter. Outcomes were compared to patients in the traditional pathway (standalone DISE followed by HGNS implantation on a later date). A total of 68 patients (13 streamlined, 55 traditional) with obstructive sleep apnea who underwent HGNS implantation were included. Patients were predominately male (70.6%) and White (95.6%) and had a mean (SD) age of 63.5 (10.0) years. The streamlined pathway was associated with a significant reduction in both hospital costs (mean difference $9258, 95% confidence interval [CI]: 3690-14,825; P = .002) and time to surgery (mean decrease of 3.82 months, 95% CI: 0.83-6.80 months; P = .013) compared to the traditional pathway. Patients in both groups had reduction in apnea-hypopnea index and Epworth Sleepiness Scale score, with no significant differences in comparisons between groups. In select patients, the streamlined HGNS pathway may expedite time to surgery and reduce hospital costs with comparable clinical outcomes to a traditional 2-stage pathway. Further research is warranted to validate patient selection and better understand longitudinal outcomes.

Orthodontic perspectives of obstructive sleep apnea

OSA is defined as a condition in which there is repetitive partial or complete collapse of the pharynx during sleep. An apnea is defined as an almost complete (at least 90%) cessation of airflow, and hypopnea is defined as a reduction in nasal pressure amplitude of at least 50% and/ or a reduction in thoracoabdominal movement of 50% or more for a minimum of 10 seconds. Often, patients first seek an otorhinolaryngologic (ENT) evaluation rather than presenting to a sleep center. Normal sleep involves air passing through and going directly down to the lungs. With an obstructed airway, the structures in the back of the throat (the tongue, the tonsils, and/or adenoids) occlude the airway due to an inadequate motor tone of the tongue and/or airway dilator muscles, and thus, prevent the air from passing. The aetiology is multifactorial, and the main risk factors in children include adenotonsillar hypertrophy, obesity, neuromuscular disorders and craniofacial anomalies. Adenotonsillar hypertrophy is the most commonly reported aetiological factor. Therefore, the treatment of choice for paediatric OSA is adenotonsillectomy. In adulthood, the use of oral appliances is a treatment option in the management of OSA

The BCOR-rearranged sarcoma involving the lung: Diagnosis with clinical outcome and literature review.

BCOR-rearranged sarcomas (BRS) constitute relatively newly described sarcomas, which, within the musculoskeletal sites, usually occur in the bones, followed by soft tissues. Primary BRS involving the visceral organs is very rare, and only a single case is reported in the lung. These tumors share overlapping morphological and immunohistochemical (IHC) features with other neoplasms, such as synovial sarcoma, Ewing sarcoma, as well as carcinosarcoma, the latter especially when occurring in the visceral organs. BCOR immunostaining is useful in triaging a tumor for molecular diagnosis, which constitutes the "essential" diagnostic criterion for these tumors. To report an extremely rare case of a BRS, confirmed by BCOR-rearrangement by fluorescence in situ hybridization (FISH), primarily occurring in the lung, emphasizing the diagnostic approach and management, along with review of literature. An18-year-old boy presented with complaints of left-sided chest pain, along with cough, fever, loss of appetite, and weight. On radio imaging, there was a complete collapse of the left lower lobe of lung with moderate pleural effusion. The biopsy showed a biphasic tumor comprising primitive round cells admixed with spindle cells. Immunohistochemically, the tumor cells were positive for BCOR, TLE1, and p53. FISH showed BCOR gene rearrangement. A diagnosis of primary BRS of lung was offered. The patient had a favorable response to the chemotherapy regime. BRS is an ultra-rare tumor, which rarely involves visceral organs. The lung is an exceptionally rare site, with only single reported case previously. An exact confirmation by molecular testing has treatment-associated implications. A review of similar reported cases is presented herewith.

Seismic Assessment of Masonry Minarets under Different Earthquakes

Minarets are tall and slender structures and form important elements of mosques. Most historical minarets are constructed with masonry (brick or stone units), while modern minarets typically use reinforced concrete. Recent earthquakes have shown that the majority of these structures are highly susceptible to seismic excitation leading to a range of structural damage, from minor cracking to complete collapse. In this paper, the seismic response of a representative masonry minaret was investigated using acceleration records of the 1999 Kocaeli, 2003 Bingöl and 2011 Van earthquakes. All acceleration records were scaled according to the location of the minaret. For this purpose, a representative masonry minaret that is thought to have been built in the city's central part of Elazığ, Turkey was chosen. After the seismic analysis, displacement and stress values obtained on the minaret were presented. It was seen that the displacements were increased along the height of the minaret. Also, the maximum and minimum stress values were obtained between the cylindrical body and transition segment of the minaret in accordance with the damage zones in the past earthquakes.

Baseline Characteristics Associated with Hypoglossal Nerve Stimulation Treatment Outcomes in Patients with Obstructive Sleep Apnea: A Systematic Review.

Hypoglossal nerve stimulation (HGNS) has emerged as an effective treatment for obstructive sleep apnea (OSA). Identifying baseline characteristics that prospectively could predict treatment outcomes even better is crucial for optimizing patient selection and improving therapeutic success in the future. A systematic review was conducted following PRISMA guidelines. Literature searches in Medline, Web of Science, and Cochrane databases identified studies assessing baseline characteristics associated with HGNS treatment outcomes. Inclusion criteria focused on studies with adult patients diagnosed with OSA, treated with HGNS, and assessed using full-night efficacy sleep studies. Risk of bias was evaluated using the NICE tool. Twenty-six studies met the inclusion criteria. Commonly reported baseline characteristics with predictive potential included BMI, site of collapse, and various pathophysiological endotypes. Most studies used the original Sher criteria to define treatment response, though variations were noted. Results suggested that lower BMI, absence of complete concentric collapse at the palatal level, and specific pathophysiological traits were associated with better HGNS outcomes. This review identified several baseline characteristics associated with HGNS outcomes, which may guide future patient selection. Importantly, patients were already preselected for HGNS. Standardizing response criteria is recommended to enhance the evaluation and effectiveness of HGNS therapy in OSA patients.

Tracheal Stent Placement In A Difficult Airway In A Patient With Central Airway Obstruction With Anterior Mediastinal Mass –A Case Report

Central airway obstruction due to benign and malignant aetiologies can result in life-threatening airway emergencies. Tracheal stenting is one of the definitive approaches for symptomatic relief in inoperable case scenarios. We report a case of papillary thyroid carcinoma with an anterior mediastinal mass presenting with dyspnoea and stridor for emergency tracheal stent placement. Awake stent placement using a video laryngoscope was performed after adequate airway topicalisation, followed by fibreoptic bronchoscope (FOB)-guided negotiation. Although rigid bronchoscopy is the gold standard, it often requires general anaesthesia, which could predispose to complete airway collapse in this patient.

Combination Tonsillectomy and Hypoglossal Nerve Stimulation for Sleep Apnea Patients With Oropharyngeal Lateral Wall Collapse.

The efficacy of hypoglossal nerve stimulation (HGNS) therapy is limited by obstruction of the oropharyngeal lateral walls (OLWs). Our objective was to investigate the effect of palatine tonsillectomy on HGNS efficacy in obstructive sleep apnea (OSA)patients with OLW collapse. Case-control study of patients with moderate-to-severe OSA, complete-or-partial OLW collapse, and small tonsils (1 - 2+). Concomitant palatine tonsillectomy and HGNS (HGNS+T) were compared against a control group of patients who underwent HGNS alone. Single academic institution. Study outcomes were measures of HGNS efficacy defined asa %reduction in apnea-hypopnea index (AHI) (primary) and successful treatment response (50% AHI reduction to <15/h, logistic regression), respectively. Regression analyses quantified the additional effect of tonsillectomy (HGNS+T vsHGNS alone, independent variable) on HGNS efficacy. Analyses were adjusted for OLW collapse severity (complete vspartial), tonsil size, age, sex, body mass index, and baseline AHI. Nineteen patients underwent HGNS+T and had follow-up sleep testing for the current analysis. The control group (HGNS alone) consisted of 78 patients. Baseline demographics and OSA severity were similar between the groups, except HGNS+T group had increased prevalence of complete OLW collapse. Linear regression demonstrated that adding tonsillectomy resulted in an additional 22.9% [7.5, 35.2] reduction in AHI [95% confidence interval, CI] (P = .006), and 8.6 [1.7,43.4] (P = .010) greater odds [95% CI] of a successful treatment response with HGNS. Compared to historically poorer outcomes of HGNS in patients with OLW collapse, these early results suggest combining tonsillectomy with HGNS may represent a promising strategy to improve success rates.

Fabrication of highly heterogeneous precipitate microstructure in an α/β titanium alloy

To obtain a synergistic combination of high strength and high ductility in titanium alloys, design and creation of heterogenous precipitate microstructure have attracted increasing attention. Herein, using Ti-3Al-5Mo-4.5V (wt.%, an α/β titanium alloy) as a model alloy, we demonstrated that a highly heterogenous α-phase precipitate microstructures with well-controlled length scale of spatial heterogeneity (i.e., micron-sized primary α and nano-scale secondary α precipitates), can be synthesized through activating the ω-assisted α nucleation transformation pathway that operates in metastable β titanium alloy alone. A detailed analysis of transformation pathway for ω phase and the underlying ω-assisted α nucleation mechanisms is carried out using the integrated advanced characterizations, theoretical calculations and simulations based on DFT, and phase-field modeling. Experimental results show unambiguously that the embryonic ω particles (also known as athermal ω) with partially collapsed structure are incapable of refining secondary α (αs). In contrast, the isothermal ω particles with a complete structural collapse play an important role in assisting αs nucleation, resulting in the formation of the ultrafine αs lamellae at nanoscales after two-step aging heat treatments. The contributions from the isothermal ω particles are then quantified using first-principles calculations and phase-field simulations. It is found that, even though the solute partitioning between a growing isothermal ω particle reduces the αs nucleation driving force in the surrounding β matrix, the elastic interaction between the ω particles and the αs nucleus provides more driving force for αs nucleation at specific locations of the ω/β interface. Our work extends the microstructure design strategy based on ω-assisted α nucleation mechanism from metastable β to α/β Ti-alloys, thereby significantly widening the application space of the strategy.

Novel Thermoreversible Reverse-Phase-Shift Foam With Deployment System for Treatment of Penetrating Globe Trauma in a Newly Described Porcine Model.

The initial management of penetrating ocular injuries is a major sight-threatening problem for both civilian and military medicine. A novel device (Eye-Aid) temporarily tamponades leakage from such injuries while being easy to remove upon arrival to specialized ophthalmologic care. Eye-Aid consists of a protective eye shield with an adhesive backing that connects to a portable canister containing rapidly deployable thermoresponsive foam. The aim of this study was to compare the use of the novel Eye-Aid device to control in a new live swine ocular injury model. Bilateral penetrating ocular injuries were created on 14 male Yorkshire swine in a standardized manner using a 16-gauge needle device to puncture the central cornea and cause a full-thickness wound. Researchers randomized eye intervention side, with the contralateral eye used as paired control. Two minutes after the injury, the eye shield components of the Eye-Aid system, which has a sticky pad for attachment to the skin and a luer-lock for foam deployment, were placed bilaterally. Eight minutes after the injury, foam was deployed for the intervention eye according to the device instructions for use. For the control eye, no additional procedures were performed. Six hours post-injury, end A-scan and intraocular pressure (IOP) were measured. Primary study outcome was change in axial length of the globe. Secondary outcomes were as follows: (1) Presence of full anterior chamber collapse, defined as a lack of measurable anterior lens capsule-reflex (ALC-reflex) on A-scan and (2) change in IOP. Outcomes were analyzed as paired intra-animal data, with intervention and control data for each animal. A paired t-test was used to analyze the difference in axial length change and IOP change between treatment groups, whereas a conditional logistic regression was used to analyze dichotomous ALC-reflex outcome and estimate the odds ratio associated with the Eye-Aid device. A significant difference (P < .0001) in mean change in axial length between intervention (-210 μm) and control (-1,202 μm) groups was found. There was a significant difference in ALC-reflex presence, with 79% of eyes having an ALC-reflex in the intervention group, compared to 14% in the control (P = .008). IOP remained higher in the intervention group, with a mean change of -1.5 mmHg for the intervention group compared to -4.0 mmHg in the control (P = .0001). This study describes the first development of an in vivo large animal ocular injury model that realistically approximates the emergent time course and pathophysiology of patients with full-thickness corneal open globe injuries. It also gives the first description of using thermoreversible hydrogel foam for such injuries. Eye-Aid was found to be significantly better than control for treatment of such injuries, based on measurements of both structure and pressure. Assuming that the absence of an ALC-reflex demonstrates complete anterior chamber collapse, the Eye-Aid group demonstrated a 79% eye "save" rate compared to only 14% in the control group, as described earlier. This results in a Number Needed to Treat of 3 for this finding. Eye-Aid additionally demonstrated several characteristics that would be beneficial in a device targeted for emergent deployment by non-ophthalmologists.

Melting of Totten Glacier, East Antarctica since the Last Glacial Maximum Revealed by Beryllium Isotope Ratios of Marine Sediment

The Totten Glacier of East Antarctica drains a basin containing about 3.5 m of sea-level rise equivalent ice. While Totten Glacier is generally considered somewhat more stable than the rapidly retreating sectors of the West Antarctic Ice Sheet, such as the Amundsen Sea Embayment and Getz Ice Shelf, our understanding of its intricate dynamics and interaction with the Southern Ocean since the Last Glacial Maximum remains incomplete. Situated in a precarious position grounded below sea level, Totten Glacier represents a critical yet enigmatic component of East Antarctic ice dynamics. Its susceptibility to marine ice sheet instability raises concerns, as positive feedback from grounding line retreat could trigger irreversible ice discharge or even complete collapse. A meticulous reconstruction of the retreat history of the Totten Glacier is imperative to comprehensively grasp the glacier's response to present and future climate changes.Here, we present a beryllium isotope ratio analysis of marine sediment from the continental slope proximal to Totten Glacier, the first such record from this location, supplemented by grain size data from the same sediment core. The results, when evaluated together with nearby proxy records, reveal that the initial deglaciation of the Totten Glacier sector of the East Antarctic Ice Sheet began at ca. 21 ka BP. The rapid deglaciation from ca. 7 ka BP that followed is determined to be caused by the intrusion of modified Circumpolar Deep Water, leading to melting at the grounding zone of the Totten Glacier and causing instability of the glacier system. The southward shift and intensification of Antarctic easterlies may be one of the causes of this intrusion. These results contribute to the body of knowledge regarding the dynamical response of marine-terminating glaciers to climate variability during the last deglaciation.

Collapse of the Dharahara Tower During the April 25, 2015 Nepal Earthquake: A New Interpretation Based on Video-Camera Footage

ABSTRACT Among the various important monuments impacted by the April 25, 2015 Mw7.8 Nepal earthquake, the Dharahara Tower located in Kathmandu suffered complete collapse. The collapse of the tower, a slender 60-meter-high old brick masonry structure with an almost cylindrical hollow shape, was captured by a low-quality video camera, which nonetheless helped to identify the critical moments. Initially, the tower descended more than 10 m vertically after a rupture at the base. After a few seconds, it overturned, disintegrating upon impact on the ground. At a distance of 1.3 km, an accelerometric station recorded the strong motion which was used as input of a discrete element model of the structure. Mechanical properties were taken from lab tests made on similar building materials. The Dharahara Tower had previously been analysed by other researchers using various methods. However, since they were apparently not aware of the mechanism observed in the video footage, their collapse models do not agree with this new evidence. For the initial phase of the collapse, the present model explains with great accuracy the observations of the video footage, but the final phase is dependent on various details, and modelling is not so robust.

Pressure Induced Nonmonotonic Evolution of Superconductivity in 6R-TaS_{2} with a Natural Bulk Van der Waals Heterostructure.

The natural bulk Van der Waals heterostructure compound 6R-TaS_{2} consists of alternate stacking 1T- and 1H-TaS_{2} monolayers, creating a unique system that incorporates charge-density-wave (CDW) order and superconductivity (SC) in distinct monolayers. Here, after confirming that the 2D nature of the lattice is preserved up to 8GPa in 6R-TaS_{2}, we documented an unusual evolution of CDW and SC by conducting high-pressure electronic transport measurements. Upon compression, we observe a gradual suppression of CDW within the 1T layers, while the SC exhibits a dome-shaped behavior that terminates at a critical pressure P_{c} around 2.9GPa. By taking account of the fact that the substantial suppression of SC is concomitant with the complete collapse of CDW order at P_{c}, we argue that the 6R-TaS_{2} behaves like a stack of Josephson junctions and thus the suppressed superconductivity can be attributed to the weakening of Josephson coupling associated with the presence of CDW fluctuations in the 1T layers. Furthermore, the SC reversely enhances above P_{c}, implying the development of emergent superconductivity in the 1T layers after the melting of T-layer CDW orders. These results show that the 6R-TaS_{2} not only provides a promising platform to explore emergent phenomena but also serves as a model system to study the complex interactions between competing electronic states.

The Jajarkot Earthquake: Revealed the Vulnerability of Load Bearing Structures in Western Nepal

The Jajarkot Earthquake, which occurred on 3rd November, 2023 of magnitude 5.7 (Mw) exposed Nepal’s longstanding vulnerability to seismic activity. This paper presents damage assessments derived from both on-site field observations and secondary resources to evaluate the damages sustained by load bearing masonry structures. In the region, 95% of the building structures are based on masonry construction. The damage status of structures in Jajarkot and Rukum East highlighted that about 50% of the building structures were partially and complete damage. The evaluation encompassed various aspects, including the types, mechanisms, and underlying causes of the damage incurred by structures. The observed damage was categorized using an established catalogue originally developed for the identification of failure mechanisms and vulnerability assessment. The common types of damage encompassed features like cracks in the load bearing external walls and corners, diagonal cracks originating from door and window corners, vertical out-of-plane displacement of external walls, collapse of external walls, and partial collapse of load bearing internal walls, fracturing of window and door lintels and complete collapse of structure. Some special forms of damage which was of new nature and distinct from those observed in prior seismic events such as the Gorkha earthquake included ruptures in the outer surfaces of loadbearing external walls, partial roof structure collapses, out-of-plane fragmentation or disintegration as well as rupture. The causes underlying this general damage were attributed to irregular bonding systems, weak mortar, stone block formation, size of stone blocks, absence of tie beams, weakly connected corners, insufficient connections of wall-roof and wall-floor systems, and differing internal wall systems. The mechanisms of damage varied based on the number and specifics of these causative factors, as well as certain structural attributes.

Predictors of surgical intervention in first episode primary spontaneous pneumothorax requiring chest drain insertion.

Primary spontaneous pneumothorax occurs in patients with no underlying lung disease and guidelines recommend chest tube drainage for the first episode, with surgical intervention reserved for recurrent episodes, persistent air leak or failure of lung re-expansion. Modern surgical management is associated with reduced length of hospital stay and superior freedom from recurrence compared with chest tube drainage alone. The objective of this study was to identify risk factors for failed chest tube drainage in patients who present with first episode primary spontaneous pneumothorax. A retrospective analysis of patients who presented to Royal Prince Alfred Hospital, Australia with first episode PSP and underwent chest tube insertion was performed. Patient demographics and size of pneumothorax were examined in relation to the primary outcome, a composite of failed chest tube drainage and recurrent ipsilateral pneumothorax. Fifty-five patients underwent chest tube drainage for first episode primary spontaneous pneumothorax between 1st January 2017 and 31st December 2020. Complete lung collapse on admission chest x-ray was associated with an increased risk of the primary outcome (63% versus 19%, OR 7.3 [96% CI 2.0-27.4), P = 0.004). This small retrospective study found that patients that undergo chest drain insertion for first episode primary spontaneous pneumothorax who present with complete lung collapse on admission are at high risk of requiring pleurodesis and therefore may benefit from early surgical referral.

Mapping rockfall hazard and detecting precursory damage in rock slopes with passive seismic: Lessons from the La Praz case-study

We conducted repeated successive passive seismic surveys on the La Praz unstable rock slope (∼13,000–15,000 m3, Savoie, France), spanning over more than ten years. The last survey was conducted two months before its complete collapse in August 2023. We used the amplitude of Horizontal to Vertical Spectral Ratio at peak (aHVSR(fp)) to discriminate stable from unstable areas and delineate the fractures with major mechanical decoupling effect. We also classified the compartments in terms of rockfall hazard: the most prone-to-fall areas showed the highest aHVSR(fp) (in the range [26–157]), compared to [7.5–19] on intermediate areas and 2.7 on adjacent stable rock mass.The frequency of HVSR main peak (fp) on three unstable rock compartments showed unambiguous −15%, −14% and −11% drops prior to the collapse. These drops significantly exceed the range of environmentally driven resonance frequency wandering observed on site and generally reported as a limitation in the literature. These drops were interpreted as progressive in-depth slope damage. Interestingly, fp losses were detected solely on the three most prone-to-fall rock compartments showing the highest aHVSR(fp). The unveiling of in-depth damage processes on such a complex, heterogenous and highly fractured rock slope using passive seismic is a first.