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Objective The risk of embolization to distal territory or to new territory in mechanical thrombectomy remains a major issue despite advancements in technological device. This condition can be caused by a large and firm dropped thrombus without passing through a guiding catheter during stent retriever or aspiration catheter withdrawal. This report introduced a novel technique referred to as retrograde angiography to detect dropped thrombus. Methods The retrograde angiography to detect dropped thrombus technique is a kind of retrograde angiography that consists of a contrast medium injection via a distal microcatheter and aspiration through an inflated balloon-guiding catheter. This method was used to detect dropped thrombus at the balloon-guiding catheter tip when back flow was blocked from the balloon-guiding catheter after stent retriever or aspiration catheter withdrawal. We retrospectively reviewed four consecutive patients who underwent the retrograde angiography to detect dropped thrombus technique during mechanical thrombectomy for acute ischemic stroke due to large vessel occlusion in the anterior circulation between January 2018 and January 2021. Results Three of four patients had dropped thrombus, which was diagnosed with the technique and retrieved completely with subsequent procedures while maintaining the balloon-guiding catheter inflated. None of the patients experienced embolization to distal territory/embolization to new territory, and a successful reperfusion was achieved in all four cases. Conclusions The retrograde angiography to detect dropped thrombus is a technique to detect a dropped thrombus at the balloon-guiding catheter tip and allows us to retrieve it with subsequent mechanical thrombectomy procedures while maintaining the balloon-guiding catheter inflated and it may be useful for reducing the risk of embolization to distal territory/embolization to new territory.

Mycobacterium tilburgii, a nonculturable mycobacterium, is an important nontuberculous mycobacterium that occasionally causes serious infections in patients with cellular immune deficiencies. Due to its nonculturable nature, information about its drug susceptibility is not available, and data about its clinical response to antimycobacterial treatment remains insufficient. Here, we report a case of a patient who presented with neck swelling and was finally diagnosed with cervical abscess caused by M. tilburgii carrying anti-interferon gamma autoantibodies using a molecular method. The relevant literature was reviewed in the context of epidemiological and clinical data on M. tilburgii infections. In this report, 15 patients were reported to be infected with M. tilburgii. Almost all patients had a cellular immune deficiency and presented with disseminated infections. Multiple refractory or relapse cases that often required prolonged antimycobacterial treatment have been reported, although a few fatal cases have also been reported. In conclusion, M. tilburgii is an important pathogen in patients with cellular immune deficiency. Physicians should thoroughly investigate cellular immune deficiency, including adult-onset immune deficiency with anti-interferon gamma autoantibodies, in patients with M. tilburgii infection.

Dorsal arachnoid web (DAW) is a rare entity, which has been reported only in the thoracic spine. The authors report the first case of DAW developing in the cervical spine. A 78-year-old man with several-year progressive gait disturbance and bilateral lower-extremity numbness was referred to our hospital on the suspicion of a non-enhancing cystic cervical spinal tumor. Magnetic resonance imaging (MRI) showed a focal indentation along the dorsal surface of the spinal cord at C7 associated with widened cerebrospinal fluid (CSF) space and increased T2-weighted signals in the cord at C5–C7. DAW was suspected, but because of the atypical location for DAW, computed tomography (CT) myelogram was performed and demonstrated an incomplete blockage of the CSF flow at C7 with neither visible abnormal membranes nor a cyst formation. Intraoperative ultrasonography and operative findings revealed that two fluttering membranes disturbed the CSF flow. The pathology of the excised membranes was arachnoid tissues. DAW should be suspected based on the characteristic MRI findings even if the location is in the lower cervical spine. This case seems to support the theory that DAW may be an incomplete or disrupted formation of an arachnoid cyst.

Staphylococcus epidermidis is a common cause of health care-associated bacteremia, especially in patients with an indwelling medical device. However, S. epidermidis is an uncommon causative organism in catheter-associated urinary tract infection, and rare pyelonephritis without any indwelling urinary device. To our knowledge, there are few cases reported of bacteremia secondary to urinary tract infection. We report two cases of pyelonephritis with bacteremia by S. epidermidis in male patients with unilateral nephrolithiasis and review prior case reports.Case 1: 74-year-old man with a history of diabetes and overactive bladder had fever and pyuria with a right nephrolithiasis on abdominal CT scan. Case 2: 79-year-old man with a history of diabetes and post-myocardial infarction status had fever with a left nephrolithiasis on abdominal CT scan. In both cases, both the urine culture collected at ureteral stenting and blood culture were positive for S. epidermidis. We initiated intravenous antibiotics in these patients in addition to ureteral stenting.S. epidermidis is acknowledged as an uncommon pathogen that can cause bacteremia secondary to pyelonephritis without an indwelling urinary device. Clinicians should consider the possibility of pyelonephritis due to S. epidermidis if the pathogen is identified in blood and urine in patients with nephrolithiasis.

Frequent and uncontrolled interruptions by information systems that do not reflect the user’s state can result in fragmented working times and decreased intellectual productivity. To avoid adverse interruptions, interruptibility estimation methods based on PC operation information have been proposed. However, workers who use PCs to accomplish their primary tasks occasionally engage in paperwork. Occasional paperwork activities, which are not reflected in the PC’s operation information, can cause estimation errors. This study focuses on using the position of the head, posture, temporal motion, and continuity of the head position and posture while a worker is at his or her desk as indices to reflect engagement in the task at hand. Based on an analysis of the relationship between the head-related parameters and interruptibility, an interruptibility estimation algorithm is proposed using four head-related indices that reflect interruptibility during PC and non-PC work. Experiments indicate that estimation acc...

To relieve the cognitive impact of interruptions caused by email delivery notifications, we propose an automatic email delivery mediation system based on the user interruptibility, which is estimated from the PC operation activity. A prototype system has been developed to be compatible with existing email clients and to deliver emails at higher estimated interruptibility times, especially at application switching moments that are considered as breakpoints in PC tasks. Trial use by eight participants in ordinary working environments suggested that email notifications were delivered at moments with lower levels of operation activity and the feelings of hindrance were decreased. Further study is to be conducted to investigate the effect of automatic email delivery mediation on the cognitive cost and work efficiency.

In order to manage interruptions adequately, the prediction of an office worker’s uninterruptible duration is desired. We assumed three factors that may affect this uninterruptible duration: the type of work, the person’s level of concentration, and the frequency with which the person is disturbed by others. For features related to the type of work, we adopted category of using application and determined the ratio of key-to-mouse usage. The rates of keystroke and mouse operation and the application-switching frequency were selected to reflect a person’s concentration at work. A time of day was selected as an index which reflects the disturbance frequency. We then analyzed the relationship between these indices and the uninterruptible duration using 1200-h data. The results showed that, except for the time of day, a significant relationship exists between the uninterruptible duration and these indices. The combination of these indices appears promising for predicting the uninterruptible duration.

To eliminate the distraction caused by inappropriately timed e-mail delivery notification, we constructed a prototype e-mail delivery mediation system. The system was designed to mediate incoming e-mails based on user interruptibility, which is estimated from PC operational activities of the user. The system delivers e-mails at higher interruptibility times, especially at application switching moments, which are considered a substitute for task breakpoints in work which uses PC. A trial experiment with eight participants in an ordinary working environment was conducted. The experiment results suggested that e-mails were delivered at higher estimated interruptibility times and decreased feelings of hindrance regarding incoming e-mails. However, there were e-mail deliveries at low interruptibility moments even though participants were using the system. Therefore, further study must be conducted to improve the system and to conduct analysis on work efficiency.

Experiments performed in controlled environments have revealed that interruptions occurring at application switching (AS), which correspond to task breakpoints in the computer field, are more subjectively acceptable and require shorter resumption lags (RL), which indicate the cognitive cost. Therefore, in this study, we investigate RLs in uncontrolled office environment. The interruptions at more acceptable ASs were expected to show shorter RLs, because the cognitive costs of the interruption are less. However, contrary to the expected result, the RLs were longer. This implies that factors other than cognitive cost may affect interruptibility in a realistic environment.

The chances of being interrupted by online communication systems, such as email, instant messenger, and micro-blog, are rapidly increasing. For the adequate control of interruption timing, the real-time estimation of the interruptibility of the user is required. In this study, we propose an interruptibility estimation method using PC activity and conversational voice detection based on the wavelet transform. The offline estimation was applied to a dataset of 50 hours obtained from 10 users. The results indicated the feasibility of improving the interruptibility estimation accuracy by the automatic detection of the existence and end of conversations.

Decision rules in if-then form are highly readable and suitable for the situations in which users need to understand the rules intuitively. When we suppose the situation in which someone reads rules, a set of decision rules is desired to satisfy the following three conditions: 1) They can explain most of possible situations as a rule set, 2) The size of a rule set is small and thus memorable, 3) Description of each rule is simple and easily understood. In general, however, it is difficult to achieve both 2) and 3) under the condition 1). In addition to typical reduction of attributes, we consider reduction of attribute domains, the number of possible attribute values in each attribute, aiming at obtaining simpler but more readable rules. It brings a large variety of granularity in data representation. Using previously proposed some criteria on the basis of 1) through 3), we rated rule sets obtained at specified levels of granularity in some real-life datasets. The rating was almost consistent to that by a human inspector in readability.

Tree-type expression of multi-class problems is known to be useful for drawing several insights from a given problem and for improving the performance of classifiers. The authors have already proposed a bottom-up procedure to construct such a tree, called a “class decision tree”, but a top-down procedure is still worth studying. In this paper, we propose a simple top-down procedure, and compare those two procedures. In addition, we discuss the effectiveness of classifier selection and feature selection applied to every node in class decision trees, and the preferable order of them as well.

Feature selection is an important technique in pattern recognition. By removing features that have little or no discriminative information, it is possible to improve the predictive performance of classifiers and to reduce the measuring cost of features. In general, feature selection algorithms choose a common feature subset useful for all classes. However, in general, the most contributory feature subsets vary depending on classes relatively to the other classes. In this study, we propose a classifier as a decision tree in which each leaf corresponds to one class and an internal node classifies a sample to one of two class subsets. We also discuss classifier selection in each node.

In pattern recognition, feature selection is an important technique for reducing the measurement cost of features or for improving the performance of classifiers, or both. Removal of features with no discriminative information is effective for improving the precision of estimated parameters of parametric classifiers. Many feature selection algorithms choose a feature subset that is useful for all classes in common. However, the best feature subset for separating one group of classes from another may depend on groups. In this study, we investigate the effectiveness of choosing feature subsets depending on groups of classes (class-dependent features), and propose a classifier system that is built as a decision tree in which nodes have class-dependent feature subsets.