The Role Of Ventriculoatrial Shunts For The Shunt Placement In Modern Medicine : A Case Report

Introduction: Although Ventriculoatrial (VA) shunt is one of the oldest solution for hydrocephalus, after the recognition of serious complication and operative difficulties, VA shunt procedure has fallen into disrepute. Since 1970s, most of neurosurgeons has changed their practice from VA shunt to ventriculoperitoneal (VP) shunt. It provides a prolong relief of intracranial pressure and easy to be performed. However, shunt revision may still be expected due to shunt infection, obstruction, migration and so on. When the peritoneum is precluded and no more available owing to the intra-abdominal adhesions, local sepsis and scarring from the previous surgery, VA shunt can be one of the choices to do the shunt revision. Whenever laparotomy for VP shunt has high possibility of serious complications and operative difficulties due to preexisting peritoneal compolication, VA shunt can be a safe and effective alternative in the neurosurgeon’s armamentarium for the cerebrospinal fluids (CSF) drainage. Case Report: In this case report, we described a case of premature 6-month-old baby boy with hydrocephalus, whose abdominal cavity had the previous history of peritonitis and stoma placement.   Result: Because his abdominal condition excluded placement of a distal catheter for VP shunt, VA shunt was planned as alternative procedure for VP shunt. Conclusion: Role of VA shunt in the era of modern neurosurgery is also discussed based on the literature review

Intraventricular Fluid Injection as a Novel Treatment of Subdural Fluid Collection after VP Shunt Overdrainage: A Case Report

Introduction: Subdural fluid collection is one of many complications of ventriculoperitoneal (VP) shunt. Variety of surgical procedures have been applied for the treatment of the post VP shunt subdural fluid collection, but the ideal surgical treatment remains controversial. Case Report: This is a case report of 14 years old boy who had a history of multiple VP shunt revisions for post hemorrhagic hydrocephalus with subdural fluid collections due to cerebrospinal fluid (CSF) overdrainage. Result: The author performed intraventricular fluid injection via shunt valve to expand the brain mantle and drain the subdural fluid through a small craniotomy. This is the first case report using the novel “fluid infusion” technique for the treatment of intractable subdural fluid collection after the VP shunt overdrainage. Conclusion: The technique can bring potentially great impact for the future treatment of symptomatic subdural fluid collection associated with CSF overdrainage after VP shunt

Quantum gapped state in a spin-1/2 distorted honeycomb-based lattice with frustration

We successfully synthesized ($p$-Py-V)[Cu(hfac)$_2$], a verdazyl-based complex. Molecular orbital calculations revealed five types of intermolecular interactions between the radical spins and two types of intramolecular interactions between the radical and the Cu spins, resulting in a spin-1/2 distorted honeycomb-based lattice. Additionally, competing ferromagnetic and antiferromagnetic (AF) interactions induce frustration. The magnetization curve displayed a multistage increase, including a zero-field energy gap. Considering the stronger AF interactions that form dimers and tetramers, the magnetic susceptibility and magnetization curves were qualitatively explained. These findings demonstrated that the quantum state, based on the dominant AF interactions, was stabilized due to the effects of frustration in the lattice. Hence, the exchange interactions forming two-dimensional couplings decoupled, reducing energy loss caused by frustration and leading to frustration-induced dimensional reduction.Comment: 6 pages, 5 figure

Field-induced quantum phase in a frustrated zigzag-square lattice

This study presents the experimental realization of a spin-1/2 zigzag-square lattice in a verdazyl-based complex, namely ($m$-Py-V-2,6-F$_2$)$[$Cu(hfac)$_2]$. Molecular orbital calculations suggest the presence of five types of frustrated exchange couplings. Our observations reveal an incremental increase in the magnetization curve beyond a critical field, signifying a phase transition from the antiferromagnetic ordered state to a quantum state characterized by a 1/2 plateau. This intriguing behavior arises from the effective stabilization of a zigzag chain by the external fields. These results provide evidence for field-induced dimensional reduction in a zigzag-square lattice attributed to the effects of frustration.Comment: 5 pages, 4 figure

The geomorphology, color, and thermal properties of Ryugu: Implications for parent-body processes

The near-Earth carbonaceous asteroid 162173 Ryugu is thought to have been produced from a parent body that contained water ice and organic molecules. The Hayabusa2 spacecraft has obtained global multi-color images of Ryugu. Geomorphological features present include a circum-equatorial ridge, east/west dichotomy, high boulder abundances across the entire surface, and impact craters. Age estimates from the craters indicate a resurfacing age of ≲ 106 years for the top 1-meter layer. Ryugu is among the darkest known bodies in the Solar System. The high abundance and spectral properties of boulders are consistent with moderately dehydrated materials, analogous to thermally metamorphosed meteorites found on Earth. The general uniformity in color across Ryugu’s surface supports partial dehydration due to internal heating of the asteroid’s parent body.Additional co-authors: N Namiki, S Tanaka, Y Iijima, K Yoshioka, M Hayakawa, Y Cho, M Matsuoka, N Hirata, N Hirata, H Miyamoto, D Domingue, M Hirabayashi, T Nakamura, T Hiroi, T Michikami, P Michel, R-L Ballouz, O S Barnouin, C M Ernst, S E Schröder, H Kikuchi, R Hemmi, G Komatsu, T Fukuhara, M Taguchi, T Arai, H Senshu, H Demura, Y Ogawa, Y Shimaki, T Sekiguchi, T G Müller, T Mizuno, H Noda, K Matsumoto, R Yamada, Y Ishihara, H Ikeda, H Araki, K Yamamoto, S Abe, F Yoshida, A Higuchi, S Sasaki, S Oshigami, S Tsuruta, K Asari, S Tazawa, M Shizugami, J Kimura, T Otsubo, H Yabuta, S Hasegawa, M Ishiguro, S Tachibana, E Palmer, R Gaskell, L Le Corre, R Jaumann, K Otto, N Schmitz, P A Abell, M A Barucci, M E Zolensky, F Vilas, F Thuillet, C Sugimoto, N Takaki, Y Suzuki, H Kamiyoshihara, M Okada, K Nagata, M Fujimoto, M Yoshikawa, Y Yamamoto, K Shirai, R Noguchi, N Ogawa, F Terui, S Kikuchi, T Yamaguchi, Y Oki, Y Takao, H Takeuchi, G Ono, Y Mimasu, K Yoshikawa, T Takahashi, Y Takei, A Fujii, C Hirose, S Nakazawa, S Hosoda, O Mori, T Shimada, S Soldini, T Iwata, M Abe, H Yano, R Tsukizaki, M Ozaki, K Nishiyama, T Saiki, S Watanabe, Y Tsud

On the origin and evolution of the asteroid Ryugu: A comprehensive geochemical perspective

Presented here are the observations and interpretations from a comprehensive analysis of 16 representative particles returned from the C-type asteroid Ryugu by the Hayabusa2 mission. On average Ryugu particles consist of 50% phyllosilicate matrix, 41% porosity and 9% minor phases, including organic matter. The abundances of 70 elements from the particles are in close agreement with those of CI chondrites. Bulk Ryugu particles show higher δ18O, Δ17O, and ε54Cr values than CI chondrites. As such, Ryugu sampled the most primitive and least-thermally processed protosolar nebula reservoirs. Such a finding is consistent with multi-scale H-C-N isotopic compositions that are compatible with an origin for Ryugu organic matter within both the protosolar nebula and the interstellar medium. The analytical data obtained here, suggests that complex soluble organic matter formed during aqueous alteration on the Ryugu progenitor planetesimal (several 10’s of km), <2.6 Myr after CAI formation. Subsequently, the Ryugu progenitor planetesimal was fragmented and evolved into the current asteroid Ryugu through sublimation

A pristine record of outer Solar System materials from asteroid Ryugu’s returned sample

Volatile and organic-rich C-type asteroids may have been one of the main sources of Earth’s water. Our best insight into their chemistry is currently provided by carbonaceous chondritic meteorites, but the meteorite record is biased: only the strongest types survive atmospheric entry and are then modified by interaction with the terrestrial environment. Here we present the results of a detailed bulk and microanalytical study of pristine Ryugu particles, brought to Earth by the Hayabusa2 spacecraft. Ryugu particles display a close compositional match with the chemically unfractionated, but aqueously altered, CI (Ivuna-type) chondrites, which are widely used as a proxy for the bulk Solar System composition. The sample shows an intricate spatial relationship between aliphatic-rich organics and phyllosilicates and indicates maximum temperatures of ~30 °C during aqueous alteration. We find that heavy hydrogen and nitrogen abundances are consistent with an outer Solar System origin. Ryugu particles are the most uncontaminated and unfractionated extraterrestrial materials studied so far, and provide the best available match to the bulk Solar System composition

A dehydrated space-weathered skin cloaking the hydrated interior of Ryugu

Without a protective atmosphere, space-exposed surfaces of airless Solar System bodies gradually experience an alteration in composition, structure and optical properties through a collective process called space weathering. The return of samples from near-Earth asteroid (162173) Ryugu by Hayabusa2 provides the first opportunity for laboratory study of space-weathering signatures on the most abundant type of inner solar system body: a C-type asteroid, composed of materials largely unchanged since the formation of the Solar System. Weathered Ryugu grains show areas of surface amorphization and partial melting of phyllosilicates, in which reduction from Fe3+ to Fe2+ and dehydration developed. Space weathering probably contributed to dehydration by dehydroxylation of Ryugu surface phyllosilicates that had already lost interlayer water molecules and to weakening of the 2.7 µm hydroxyl (–OH) band in reflectance spectra. For C-type asteroids in general, this indicates that a weak 2.7 µm band can signify space-weathering-induced surface dehydration, rather than bulk volatile loss

Development of Numerical Model of the Thermal State of an Asteroid with Locally Rough Surface and Its Application

We present a numerical method for simulating a disk-resolved thermal image of an asteroid with small-scale roughness. In our method, we carry out numerical thermal evolution model of a small but rough area taking into account its latitude, shadowing effect, and re-absorption of the thermal radiation by neighbor. By visualization of the resulting temperature distribution for an observation direction, we obtain the thermal flux from the area as a function of the observation direction. Then thermal image of an asteroid with random topography is constructed. The resulting daytime temperature evolution profile is different from the well-known parabolic shape due to the surface roughness, implying that the daytime temperature evolution profile is a diagnostic to evaluate the surface roughness. Although this model is inapplicable to a morphologically complex asteroid such as Itokawa, the target body of Hayabusa2, Ryugu is generally convex and suitable for application of our model. Furthermore, the study presents predictions of the location shift of Ryugu trajectory after one orbital rotation due to the thermal moment caused by the rebound force from thermally emitted photons known as the Yarkovsky effect. This model is thus verifiable by precise calculation of the ephemeris of Ryugu