Worm blobs as entangled living polymers: from topological active matter to flexible soft robot collectives.

Recently, the study of long, slender living worms has gained attention due to their unique ability to form highly entangled physical structures, exhibiting emergent behaviors. These organisms can assemble into an active three-dimensional soft entity referred to as the "blob", which exhibits both solid-like and liquid-like properties. This blob can respond to external stimuli such as light, to move or change shape. In this perspective article, we acknowledge the extensive and rich history of polymer physics, while illustrating how these living worms provide a fascinating experimental platform for investigating the physics of active, polymer-like entities. The combination of activity, long aspect ratio, and entanglement in these worms gives rise to a diverse range of emergent behaviors. By understanding the intricate dynamics of the worm blob, we could potentially stimulate further research into the behavior of entangled active polymers, and guide the advancement of synthetic topological active matter and bioinspired tangling soft robot collectives.

Correction: Passive particle transport using a transversely propelling polymer "sweeper".

Correction for 'Passive particle transport using a transversely propelling polymer "sweeper"* by K. R. Prathyusha, Soft Matter, 2023, 19, 4001-4010, https://doi.org/10.1039/d2sm01708c.

Passive particle transport using a transversely propelling polymer "sweeper".

Using Langevin dynamics simulations, we study a system of a transversely propelling polymer and passive Brownian particles. We consider a polymer whose monomers experience a constant propulsion force perpendicular to the local tangents, surrounded by passive particles undergoing thermal fluctuations in two dimensions. We demonstrate that the sideways propelling polymer can act as a sweeper to collect the passive Brownian particles, mimicking a shuttle-cargo system. The number of particles the polymer collects during its motion increases with time and finally saturates to a maximum number. Moreover, the velocity of the polymer decreases as the particles get trapped due to the extra drag they generate. Rather than going to zero, the polymer velocity eventually reaches a terminal value close to the contribution from the thermal velocity when it collects the maximum load. We show that, apart from the length of the polymer, the propulsion strength and the number of passive particles are the deciding factors for the maximum trapped particles. In addition, we demonstrate that the collected particles arrange themselves in a triangular, closed, packed state, similar to what has been observed in experiments. Our study reveals that the interplay between stiffness and active forces induces morphological changes in the polymer during particle transport, suggesting novel ways of designing robophysical models for particle collection and transport.

Labyrinthine Fistula-Our Experience at a Tertiary Hospital.

This study has aimed to determine the anatomical site of labyrinthine fistula in patients of chronic suppurative otitis media at our centre. Labyrinthine fistulae (LF) are caused by abnormal communications between the inner ear and surrounding structures resulting in perilymph leakage and hearing loss. Labyrinthine fistula represents as erosive loss of the enchondral bone overlying the semicircular canals without loss of perilymph. The manifestations of fistula like vertigo, hearing loss vary in severity and complexity, commonly ranging from very mild to incapacitating. Cholesteatoma induced fistula most commonly involves lateral semicircular canal probably because of its close proximity to the middle ear, but can involve other semicircular canals and rarely cochlea. This is a retrospective analysis of 36 patients of chronic suppurative otitis media with history of vertigo undergoing tympanomastoid surgery in whom there was an evidence of labyrinthine fistula on HRCT scan of temporal bone. The incidence of patients with labyrinthine fistula presenting with vertigo, nystagmus, sensorineural hearing loss, history of vertigo were analysed. The anatomical location of the fistula was supported by Radiological evidence. Patients underwent either canal wall down mastoidectomy or cortical mastoidectomy. The anatomical site and length of the labyrinthine fistula were analysed. Amongst the 36 patients of chronic suppurative otitis media with labyrinthine fistula 22 (61.1%) patients had atticoantral disease, 4 (11.1%) patients had chronic otitis media with extensive granulation, 2 (5.5%) patients had Tubotympanic disease with polyps, 4 (11.1%) patients had Tuberculous otitis media, 1 (2.77%) patient had Tubotympanic disease with extensive tympanosclerosis eroding the dome of lateral semicircular canal, 1 (2.77%) patient had extensive cholesteatoma with cerebellar abscess, 1 (2.77%) patient had fistula in the promontory following trauma, 1 (2.77%) patient had extensive tympanosclerosis with erosion of promontory. It was noticed that, in 14 (38.88%) patients the fistula was at the centre, in 17 (47.22%) patients the fistula is towards the ampullary end of horizontal semicircular canal and in 5 (13.88%) patients the fistula was towards the non ampullary end of lateral semicircular canal. The maximum length of fistula noticed was 6 mm and the minimum length of the fistula noticed was 2 mm. Labyrinthine fistula are most commonly noticed in the ampullary end of the lateral semicircular canal. The average length of the fistula was found to be 4 mm. Careful elevation of the cholesteatoma matrix over the endosteal membrane and immediate placement of temporal fascia over the exposed fistula is important to avoid injury to the inner ear. Maximum number of fistula were seen in the atticoantral type of Chronic suppurative otitis media. Prior knowledge of anatomical location of the fistulous tract in HRCT temporal bone is important to address the fistula.

Extensive Cholesteatomas: Presentation, Complications and Management Strategy.

To document the clinical presentation, complications, management strategy and post-operative outcomes of extensive cholesteatomas. Cholesteatoma is a well demarcated cystic lesion derived from an abnormal growth of keratinizing squamous epithelium in the temporal bone. Cholesteatomas commonly involve the middle ear, epitympanum, mastoid antrum and air cells and can remain within these confines for a considerable period. Bony erosion is present confined to ossicular chain and scutum initially, but as the cholesteatoma expands, erosion of the otic capsule, fallopian canal and tegmen can occur. Erosion of the tegmen tymapani or tegmen mastoideum may lead to development of a brain hernia or cerebrospinal fluid leakage. Invasion of jugular bulb, sigmoid sinus, internal carotid artery are noticed in extensive cholesteatoma and are quite challenging and requires expertise. Neurosurgical intervention should be considered along with the otological management in the same sitting in all possible cases. A retrospective review of 12 patients were carried out to assess the clinical presentation, complications, surgical management and postoperative outcomes of extensive cholesteatomas presenting at our centre between January 2017 and December 2019. CT or MRI findings, extent of cholesteatoma intra-operatively along with the status of major neurovascular structures and disease clearance, and the post-operative outcomes including morbidity and mortality were noted. All patients underwent canal wall down mastoidectomy with or without ossiculoplasty. Post operatively all patients were treated with intravenous antibiotics and if required intravenous steroids. Amongst the 12 patients of extensive cholesteatoma (EC), all of them (100%) presented with foul smelling, purulent ear discharge. 9 (75%) patients presented with otalgia. 4 (33.33%) patients had temporal headache. 10 (83.33%) patients complained of hard of hearing. 7 (58.33%) patients gives history of vertigo at the time of presentation. In 8 (66.66%) patients there was tegmen plate erosion noticed in CT scan. In 3 (25%) patients, the disease was invading the sigmoid sinus and in 1 (8.33%) patient jugular bulb was involved. In 3 (25%) cases of EC, blind sac closure was performed. In two patients who developed cerebellar abscess, drainage procedure was performed. 2 (16.66%) patients developed sigmoid sinus thrombosis, 1 (8.33%) patient had petrositis.

Emergent conformational properties of end-tailored transversely propelling polymers.

We study the dynamics and conformations of a single active semiflexible polymer whose monomers experience a propulsion force perpendicular to the local tangent, with the end beads being different from the inner beads ("end-tailored"). Using Langevin simulations, we demonstrate that, apart from sideways motion, the relative propulsion strength between the end beads and the polymer backbone significantly changes the conformational properties of the polymers as a function of bending stiffness, end-tailoring and propulsion force. Expectedly, for slower ends the polymer curves away from the moving direction, while faster ends lead to opposite curving, in both cases slightly reducing the center of mass velocity compared to a straight fiber. Interestingly, for faster end beads there is a rich and dynamic morphology diagram: the polymer ends may get folded together to 2D loops or hairpin-like conformations that rotate due to their asymmetry in shape and periodic flapping motion around a rather straight state during full propulsion is also possible. We rationalize the simulations using scaling and kinematic arguments and present the state diagram of the conformations. Sideways propelled fibers comprise a rather unexplored and versatile class of self-propellers, and their study will open novel ways for designing, e.g. motile actuators or mixers in soft robotics.

Modification of lipid membrane compressibility induced by an electric field.

Changes in membrane deformation and compressibility, induced by an external electric field, are investigated using coarse-grained martini force field simulations in a salt-free environment. We observe changes in the area of the membrane above a critical electric field. Below this value, the membrane compressibility modulus is found to decrease monotonically. For higher electric fields, the membrane projected area remains constant while the net interfacial area increases, with the corresponding compressibility moduli, show the opposite behavior. We find that the mechanical parameters, surface tension and bending modulus, of a freely floating membrane in the absence of explicit ions, are unaffected by the presence of the electric field. We believe these results have a bearing on our understanding of the electroformation of uncharged lipids in a salt-free environment.

Fronto Ethmoidal Mucocele Associated with Type 4 Kuhn Cells.

A mucocele is an epithelial lined mucous containing sac completely filling the sinus and capable of expansion. We report a case with unilateral frontoethmoidal mucocele in relation with type IV Kuhn cell. A 26 year old man came to the ENT department at SDUMC, Tamaka, Kolar, presenting complaints of proptosis of left eye since 3 years. After detailed examination and investigations patient was Diagnosed to have mucocele of left frontoethmoidal region. Intraoperatively we found a rare picture of type IV kuhn cells completely seated in the frontal sinus. After externally assisted modified Lothrop's approach, marsupialization of mucocele was done in the nasal cavity and symptoms of the patient relieved. We state that, in cases of frontoethmoidal mucocele, externally assisted modified Lothrop procedure offers an alternative for endoscopic management of frontoethmoidal mucocele for the complete clearance of disease.

Comparison of prevalence of life style risk factors and 10 year risk of CVD event among rural and tribal population of Kollegal Taluk, Chamrajanagar district, South India.

CONTEXT: Cardiovascular diseases have been recognized as leading cause of death. Three-fourths of CVD deaths occur in low and middle income countries. Surveillance of CVD risk factors is a key strategy for effective CVD prevention. AIMS: To identify the extent of CVD risk factors and 10 year risk of developing Cardiovascular Disease events among rural and tribal population. SUBJECTS AND METHODS: This community based cross sectional study was conducted on a total of 482 rural and 415 tribal subjects aged above 30 years from Kollegal taluk, Chamrajanagar, Karnataka, India. Tobacco and alcohol consumption, BMI, blood pressure and capillary blood glucose were estimated. WHO/ISH risk prediction chart was used to predict 10 year risk of MI/stroke. RESULTS: Tobacco consumption was 15.4% (rural) and 90.8% (tribal). Alcohol consumption was 10.8% (rural) and 21.9% (tribal), Obesity was 40.2% (rural) and 14.0% (tribal). Prevalence of Hypertension was 49.8% (rural) and 32.2% (Tribal) and diabetes 8.3% (rural) and 2.9% (tribal). Nearly one fourth of the population are at moderate risk (10-30%) and one tenth are at high risk (30%) of MI/Stroke within 10 years. CONCLUSIONS: High prevalence of tobacco consumption among tribal and high prevalence of hypertension and diabetes among rural predisposes 10% of population to moderate to high risk of stroke/MI within 10 years.

Dynamically generated patterns in dense suspensions of active filaments.

We use Langevin dynamics simulations to study dynamical behavior of a dense planar layer of active semiflexible filaments. Using the strength of active force and the thermal persistence length as parameters, we map a detailed phase diagram and identify several nonequilibrium phases in this system. In addition to a slowly flowing melt phase, we observe that, for sufficiently high activity, collective flow accompanied by signatures of local polar and nematic order appears in the system. This state is also characterized by strong density fluctuations. Furthermore, we identify an activity-driven crossover from this state of coherently flowing bundles of filaments to a phase with no global flow, formed by individual filaments coiled into rotating spirals. This suggests a mechanism where the system responds to activity by changing the shape of active agents, an effect with no analog in systems of active particles without internal degrees of freedom.

Personal authentication using hand vein triangulation and knuckle shape.

This paper presents a new approach to authenticate individuals using triangulation of hand vein images and simultaneous extraction of knuckle shape information. The proposed method is fully automated and employs palm dorsal hand vein images acquired from the low-cost, near infrared, contactless imaging. The knuckle tips are used as key points for the image normalization and extraction of region of interest. The matching scores are generated in two parallel stages: (i) hierarchical matching score from the four topologies of triangulation in the binarized vein structures and (ii) from the geometrical features consisting of knuckle point perimeter distances in the acquired images. The weighted score level combination from these two matching scores are used to authenticate the individuals. The achieved experimental results from the proposed system using contactless palm dorsal-hand vein images are promising (equal error rate of 1.14%) and suggest more user friendly alternative for user identification.