32 research outputs found

    A fully programmable 100-spin coherent Ising machine with all-to-all connections

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    Unconventional, special-purpose machines may aid in accelerating the solution of some of the hardest problems in computing, such as large-scale combinatorial optimizations, by exploiting different operating mechanisms than those of standard digital computers. We present a scalable optical processor with electronic feedback that can be realized at large scale with room-temperature technology. Our prototype machine is able to find exact solutions of, or sample good approximate solutions to, a variety of hard instances of Ising problems with up to 100 spins and 10,000 spin-spin connections

    A fully programmable 100-spin coherent Ising machine with all-to-all connections

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    Unconventional, special-purpose machines may aid in accelerating the solution of some of the hardest problems in computing, such as large-scale combinatorial optimizations, by exploiting different operating mechanisms than those of standard digital computers. We present a scalable optical processor with electronic feedback that can be realized at large scale with room-temperature technology. Our prototype machine is able to find exact solutions of, or sample good approximate solutions to, a variety of hard instances of Ising problems with up to 100 spins and 10,000 spin-spin connections

    Cyanobacterial Cell Lineage Analysis of the Spatiotemporal hetR Expression Profile during Heterocyst Pattern Formation in Anabaena sp. PCC 7120

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    Diazotrophic heterocyst formation in the filamentous cyanobacterium, Anabaena sp. PCC 7120, is one of the simplest pattern formations known to occur in cell differentiation. Most previous studies on heterocyst patterning were based on statistical analysis using cells collected or observed at different times from a liquid culture, which would mask stochastic fluctuations affecting the process of pattern formation dynamics in a single bacterial filament. In order to analyze the spatiotemporal dynamics of heterocyst formation at the single filament level, here we developed a culture system to monitor simultaneously bacterial development, gene expression, and phycobilisome fluorescence. We also developed micro-liquid chamber arrays to analyze multiple Anabaena filaments at the same time. Cell lineage analyses demonstrated that the initial distributions of hetR::gfp and phycobilisome fluorescence signals at nitrogen step-down were not correlated with the resulting distribution of developed heterocysts. Time-lapse observations also revealed a dynamic hetR expression profile at the single-filament level, including transient upregulation accompanying cell division, which did not always lead to heterocyst development. In addition, some cells differentiated into heterocysts without cell division after nitrogen step-down, suggesting that cell division in the mother cells is not an essential requirement for heterocyst differentiation

    Transvenous embolization through the ipsilateral deep facial vein: A novel approach route for treatment of a cavernous sinus dural arteriovenous fistula

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    The superior ophthalmic vein (SOV) approach through the facial vein is usually preferred for transvenous embolization of a cavernous sinus dural arteriovenous fistula (CS DAVF) when the ipsilateral inferior petrosal sinus is angiographically occluded. However, navigating the microcatheter can sometimes be difficult because of stenosis or tortuous angulation at the junction between the angular vein and SOV. We present a novel transvenous access route to treat a CS DAVF using the ipsilateral deep facial vein through the SOV to reach the cavernous sinus. A 66-year-old woman presented with left-sided chemosis, exophthalmos, and external ophthalmoplegia. Angiography showed a left CS DAVF associated with a dilated SOV and retrograde cortical venous reflux. A dilated drainage vein, which branched from the SOV, ran through the lateral aspect of the orbit and exited the orbit through the inferior orbital fissure. This vein connected with the ipsilateral deep facial vein draining into the facial and internal jugular veins. We performed transvenous embolization via the SOV approach through the deep facial vein and achieved complete obliteration, by placing 3 platinum coils, without complications. Ophthalmic veins may connect with the cavernous sinus and pterygoid plexus, passing through the superior and inferior orbital fissures, respectively. Our case suggests that the deep facial vein may provide access to the SOV through the inferior orbital fissure without passing the difficult tortuous angle between the angular vein and SOV

    Brain abscess associated with ethmoidal sinus osteoma: A case report

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    Osteoma of the paranasal sinus is uncommon, and the occurrence of brain abscess associated with ethmoidal osteoma is particularly rare. We report here a case of a brain abscess complicating an ethmoidal osteoma in a 68-year-old man who presented with high-grade fever and disturbance in the level of consciousness. Computed tomography scanning and magnetic resonance imaging revealed a ring-enhancing mass in the left frontal lobe with surrounding edema and a bony mass in the ethmoidal sinus. We scheduled a two-stage operation. First, emergency aspiration and drainage of the abscess via the forehead were performed to reduce the abscess volume. These were followed by a left frontal craniotomy to totally remove both the brain abscess and the bony mass. The bony mass had breached the dura mater. After removing the bony mass, we repaired the anterior skull base using a pericranial flap. Pathological findings of the bony tumor were consistent with osteoma. The postoperative course was uneventful. In the case of a huge brain abscess associated with an ethmoidal osteoma, volume reduction by drainage followed by surgical removal of both lesions may help to control infection and achieve a cure. Use of a vascularized pericranial flap is important to prevent direct communication between the paranasal sinuses and the cranial cavity

    Intradural Facial Nerve Schwannoma: Diagnostic and Therapeutic Problems

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    Objectives: To define characteristics of intradural facial schwannoma (FS) and discuss management strategies. Method: Retrospective review of clinical charts. Results: Six patients were diagnosed, based on surgical findings, as having intradural FS. None of the patients complained initially of facial weakness, but all showed severe disturbance of hearing function assessed on admission. FS was suspected in four of our six patients because of imaging findings or facial palsy caused by a small tumor. Total removal was performed in five cases followed by facial nerve reconstruction, and nearly total removal was performed in one case. Most patients recovered to Grade II or III palsy during the follow-up, and long-lasting palsy before surgery showed poor recovery. Conclusion: Imaging findings such as tumor extension to the middle fossa and clinical findings such as facial palsy caused by a small tumor strongly suggest a diagnosis of FS. Facial function can be restored satisfactorily for most patients after appropriate surgery
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