Symbol Emergence as an Interpersonal Multimodal Categorization.

This study focuses on category formation for individual agents and the dynamics of symbol emergence in a multi-agent system through semiotic communication. In this study, the semiotic communication refers to exchanging signs composed of the signifier (i.e., words) and the signified (i.e., categories). We define the generation and interpretation of signs associated with the categories formed through the agent's own sensory experience or by exchanging signs with other agents as basic functions of the semiotic communication. From the viewpoint of language evolution and symbol emergence, organization of a symbol system in a multi-agent system (i.e., agent society) is considered as a bottom-up and dynamic process, where individual agents share the meaning of signs and categorize sensory experience. A constructive computational model can explain the mutual dependency of the two processes and has mathematical support that guarantees a symbol system's emergence and sharing within the multi-agent system. In this paper, we describe a new computational model that represents symbol emergence in a two-agent system based on a probabilistic generative model for multimodal categorization. It models semiotic communication via a probabilistic rejection based on the receiver's own belief. We have found that the dynamics by which cognitively independent agents create a symbol system through their semiotic communication can be regarded as the inference process of a hidden variable in an interpersonal multimodal categorizer, i.e., the complete system can be regarded as a single agent performing multimodal categorization using the sensors of all agents, if we define the rejection probability based on the Metropolis-Hastings algorithm. The validity of the proposed model and algorithm for symbol emergence, i.e., forming and sharing signs and categories, is also verified in an experiment with two agents observing daily objects in the real-world environment. In the experiment, we compared three communication algorithms: no communication, no rejection, and the proposed algorithm. The experimental results demonstrate that our model reproduces the phenomena of symbol emergence, which does not require a teacher who would know a pre-existing symbol system. Instead, the multi-agent system can form and use a symbol system without having pre-existing categories.

Hierarchical Spatial Concept Formation Based on Multimodal Information for Human Support Robots.

In this paper, we propose a hierarchical spatial concept formation method based on the Bayesian generative model with multimodal information e.g., vision, position and word information. Since humans have the ability to select an appropriate level of abstraction according to the situation and describe their position linguistically, e.g., "I am in my home" and "I am in front of the table," a hierarchical structure of spatial concepts is necessary in order for human support robots to communicate smoothly with users. The proposed method enables a robot to form hierarchical spatial concepts by categorizing multimodal information using hierarchical multimodal latent Dirichlet allocation (hMLDA). Object recognition results using convolutional neural network (CNN), hierarchical k-means clustering result of self-position estimated by Monte Carlo localization (MCL), and a set of location names are used, respectively, as features in vision, position, and word information. Experiments in forming hierarchical spatial concepts and evaluating how the proposed method can predict unobserved location names and position categories are performed using a robot in the real world. Results verify that, relative to comparable baseline methods, the proposed method enables a robot to predict location names and position categories closer to predictions made by humans. As an application example of the proposed method in a home environment, a demonstration in which a human support robot moves to an instructed place based on human speech instructions is achieved based on the formed hierarchical spatial concept.

Cleanliness of Linen and Clothing Items Professionally Laundered or Dry-Cleaned.

We asked 14 professional cleaners (laundry services) to clean various unused (new) linen and clothing items with a microbial contamination level of <1 cfu/cm(2) and then evaluated the bacterial/fungal contamination of the laundered or dry-cleaned items. After laundering, 6 (21.4%) of the 28 samples from 4 of the 14 cleaners (28.6%) were contaminated (1-1,200 cfu/cm(2)). After dry-cleaning, 2 (7.1%) of the 28 samples from 2 (14.3%) of the 14 cleaners were contaminated (7-10 cfu/cm(2)). The main contaminant was Bacillus cereus. No sample of the laundered or dry-cleaned items showed Staphylococcus aureus, Escherichia coli, or Pseudomonas aeruginosa contamination. All 14 cleaners investigated in this study used batch-type washing machines. Therefore, batch-type washing machines can cause contamination of linen and clothing items with B. cereus.

Microbial contamination of surgical instruments used for laparotomy.

BACKGROUND: The aim of this study was to determine the risk of contamination of surgical instruments according to the type of instrument and the surgical procedure. METHODS: Microbiologic examination was conducted on 140 pairs of forceps used in 24 elective laparotomies. These included 60 pairs of tissue forceps and 80 pairs of DeBakey forceps. Microbes on their surface were recovered using a membrane filter method. Adenosine triphosphate assay was also performed simultaneously in each pair of forceps. RESULTS: A total of 66 strains of microbes was recovered from 44 collected instruments (31%), with microbial counts ranging from 0 to 296 colony-forming units. Among the recovered microbes, gram-positive cocci were dominant [corrected]. The remaining microbes included 6 strains of gram-positive rods and 4 strains of gram-negative rods. The most common organism was Staphylococcus epidermidis, followed by S hominis and S warneri. Residual adenosine triphosphate was not correlated with the number of recovered microbes. CONCLUSION: Surgical instruments tend to be contaminated during operations by microbes that inhabit the skin and organs. Surgical instruments could act as fomites for the pathogens of surgical site infection even if the surgical field is not apparently contaminated, through application of appropriate practices adhering to surgical site infection guidelines.

Comparison of adenosine triphosphate, microbiological load, and residual protein as indicators for assessing the cleanliness of flexible gastrointestinal endoscopes.

BACKGROUND: This study evaluated 3 potential indicators of gastrointestinal endoscope cleanliness: adenosine triphosphate (ATP), microbiological load, and protein. METHODS: Before and after cleaning, ATP and microbiological load were determined from swabs of exterior surfaces and rinses of interior suction/accessory channels. Similarly, before and after cleaning, residual protein was determined from rinses of interior suction/accessory channels. RESULTS: Before cleaning, ATP values were 10,417 relative light units (RLU) from the exterior endoscope surface and 30,281 RLU from the suction/accessory channel rinsates. After cleaning, these ATP values were decreased to 82 RLUs and 104 RLUs, a statistically significant difference. A similar trend was observed with microbiological load, but the change in residual protein from before cleaning to after cleaning was not significant. ATP values reliably reflected microbiological colony counts. CONCLUSIONS: ATP measurement can provide a reliable, rapid and practical assessment of endoscope cleanliness for routine monitoring in the clinical setting.

Evaluation with a focus on both the antimicrobial efficacy and cumulative skin irritation potential of chlorhexidine gluconate alcohol-containing preoperative skin preparations.

BACKGROUND: Important characteristics for ideal skin preparations include long-lasting antimicrobial efficacy and low potential for skin irritation. METHODS: A total of 55 healthy adult subjects were enrolled to evaluate the antimicrobial effects of 3 test formulations applied to inguinal, abdominal, and antecubital sites at post-treatment time points of 30 seconds, 72 hours, and 7 days. To investigate skin irritation potential, the 3 formulations were tested in a 21-day repeat-insult patch test conducted on the skin of the backs of 23 healthy subjects. RESULTS: The mean log(10) reduction (MLR) at 7 days post-treatment produced by a 79% vol/vol ethanol containing 1% wt/vol chlorhexidine gluconate (1% CHG-EtOH) applied to abdominal sites was significantly superior to that produced by a 10% povidone-iodine solution (2.45 MLR vs 0.90 MLR; P < .05). The 1% CHG-EtOH and a 70% vol/vol isopropanol containing 2% wt/vol CHG (2% CHG-IPA) provided statistically equivalent persistence at 72 hours and 7 days post-treatment. The 1% CHG-EtOH had less skin irritation potential than the 2% CHG-IPA and the 10% povidone-iodine solution, although the differences were not statistically significant (P > .05). CONCLUSION: Considering its persistent effect and low skin irritation potential, the 1% CHG-EtOH preparation is expected to perform well in surgical site preparation to reduce the risk of surgery- and catheter-related bloodstream infection.

A comparative clinical study focusing on the antimicrobial efficacies of chlorhexidine gluconate alcohol for patient skin preparations.

Comparative efficacy study data showed that skin preparations formulated with more than 0.5% chlorhexidine gluconate (CHG) in alcohol produced significant reductions in microbial populations at the inguinal, abdominal, and antecubital sites at each sample time (P < .05) relative to baseline, and there were no significant differences statistically, including persistent effects within 24 hours (P > .05). It would be reasonable to expect that a 1% CHG-ethanol skin preparation (with >0.5% CHG in alcohol) could be chosen in Japan that would perform well and have promising potential for catheter preparation/maintenance preparation with consideration for recommendation of the Centers for Disease Control and Prevention's guideline issued in 2011.

Heterogeneously vancomycin-intermediate Staphylococcus aureus (hVISA) emerged before the clinical introduction of vancomycin in Japan: a retrospective study.

Vancomycin-intermediate Staphylococcus aureus (VISA) and its precursor, heterogeneous VISA (hVISA), are increasingly the cause of vancomycin treatment failure. Prolonged glycopeptide treatment causes the emergence of these pathogens. However, we recently reported that hVISA can be generated by methicillin-resistant S. aureus (MRSA) exposure to imipenem (Katayama et al., Antimicrob Agents Chemother. 53:3190-6). We report here a retrospective prevalence study of VISA and hVISA on 750 MRSA clinical strains isolated from 31 Japanese national university hospitals in 1990, the year before the introduction of injectable vancomycin into clinical use in Japan in 1991. No VISA strain was identified, but population analysis identified 38 hVISA strains (5.1%) from 19 hospitals. We also determined the nucleotide sequences of vraSR, walRK, clpP, and rpoB genes whose mutations are known to be associated with vancomycin resistance. When compared with vancomycin-susceptible MRSA strain N315, six of the 38 hVISA strains possessed nonsynonymous mutations in vraSR, seven in walRK, and two in rpoB genes, Thirteen of 38 (34.2%) hVISA strains possessed at least one of these mutations. Results were consistent with our hypothesis that hVISA was present in Japanese hospitals before the clinical introduction of vancomycin.

Microbiological safety and cost-effectiveness of weekly breathing circuit changes in combination with heat moisture exchange filters: a prospective longitudinal clinical survey.

AIM: To assess the safety and cost effectiveness of a usage for seven days of breathing circuit systems (BCSs) in combination with heat moisture exchanger filters (HMEF) in operation room anesthesia. METHOD: In a prospective longitudinal clinical study, the contamination on high-risk surfaces (HMEF together with inner and outer surface of BCS) was monitored over 1, 2, 5, and 7 days. RESULTS of endogenous respiratory patient flora and contamination flora of BCS, HMEF and bag were compared. Costs of prolonged use of BCS together with HMEF up to 7 days were calculated. RESULTS: Neither physiological respiratory flora nor colonizing pathogens of the oropharynx of the ventilated patients were transmitted through the filters at any time. None of the included patients developed a postoperative pneumonia. Using the BCS for 24 hours provides a cost savings of up to 40% versus single use. Extending the change interval from 24 hours to 48 hours saved over 50% compared to change after each patient, and an additional 19% compared to change after 24 hours. In combination with a HMEF BCS can be used up to 7 days without clinical risk on multiple patients in operation room settings. CONCLUSION: Expanding the usage of berating in combination with usage of moist exchange filters is feasible, microbiologically safe and cost effective, as 41% of material costs per ventilation may be saved. Further research is needed to confirm these results.

Studies on Viral Disinfection: An Evaluation of Moist Heat Disinfection for HBV by Using A0 Concept Defined in ISO 15883-Washer-Disinfectors.

International Organization for Standardization (ISO) 15883 for washer-disinfectors has introduced the A(0) concept to allow comparison of the lethality of moist heat processes. The A(0) value is the equivalent disinfection time in seconds at 80 °C calculated on the basis of microbial killing kinetics when the disinfection temperature is over 65 °C. Hepatitis B virus (HBV), transmissible only to humans and chimpanzees, is an important heat-resistant, blood-borne pathogen. Therefore, it is mandatory to disinfect HBV thoroughly in the washer-disinfectors employed for surgical instruments. Additionally, it has become extremely difficult to use chimpanzees as experimental models or to perform human volunteer studies. Therefore, it is considered worthwhile to re-evaluate the reported data on the moist heat disinfection of HBV using the A(0) value. In the voluntary active immunization to humans in 1973, HBV serum (infectivity titer: 10(6.5) CID(50)/mL) underwent moist heat disinfection at 98 °C for 1 min in a flask over an electric burner (conservatively estimated A(0) value: 3786). Then, 0.1 mL was inoculated to each of 29 volunteers. No one revealed evidence of infection clinically or in the laboratory tests available at the time. In 1979, a more sensitive test appeared and revealed three sub-clinically infected volunteers. In the 1980s, there were two chimpanzee experimental models using HBV serum (infectivity titer: 10(5) CID(50)/mL). In one model, the serum underwent moist heat disinfection at 98 °C for 2 min in a thermostat bath (conservatively estimated A(0) value: 7571). One milliliter was inoculated to each of two chimpanzees, and both of them revealed no evidence of infection. In another model, the serum underwent moist heat disinfection using two conditions in a thermostat bath, respectively: at 103 °C for 90 s (A(0) value: 24865) and at 65 °C for 10 h (A(0) value: 1138). Ten milliliters of each sample were mixed. Then, the mixture was inoculated to each of two chimpanzees. Both of them revealed no evidence of infection. In the human volunteer study, the serum infectivity titer was more than 30 times (10(1.5) times) higher than that used in the two chimpanzee experimental models. Moreover, the serum was heated in the flask over an electric burner, which is considered less reliable than the thermostat baths to realize uniform heat distribution. It is assumed that these factors were predisposed to the result that a conservatively estimated A(0) value of 3786 failed to inactivate the HBV serum of 10(6.5) CID(50)/mL. In the two chimpanzee models, it was suggested that A(0) value not less than 1138 was able to inactivate the HBV serum of 10(5) CID(50)/mL.

Factors affecting performance of hospital infection control in Japan.

BACKGROUND: In Japan, hospital infection control (IC) programs are frequently underresourced, and their improvement is considered a pressing issue. METHODS: In 2005, we conducted a questionnaire survey of 638 teaching hospitals (most with 300 or more beds) and 882 nonteaching hospitals (most with fewer than 300 beds) in Japan. We analyzed associations among resources, infrastructures, activities, and performance related to IC. RESULTS: A total of 423 teaching hospitals (66.3%) and 377 nonteaching hospitals (50.2%) responded to the survey. The teaching hospitals had more IC infrastructure, such as full-time infection control practitioners (ICPs), link nurses, and infection control teams (ICTs), compared with the nonteaching hospitals. Infection surveillance was more likely to be implemented in hospitals with more ICP full-time equivalents (FTEs). IC performance scores were significantly higher in the teaching hospitals than in the nonteaching hospitals. In multivariate analyses, greater IC infrastructure, such as ICP FTEs, full-time IC nurses, and regular ICT rounds were significantly associated with IC performance. Hospital accreditation and hospital size also were significantly associated with higher IC performance scores. CONCLUSION: Given the strong associations found among IC infrastructure and performance, a new framework for evaluating IC infrastructure and for providing financial support may be effective in enhancing IC programs.

Impact of hospital accreditation on infection control programs in teaching hospitals in Japan.

BACKGROUND: In Japan, hospital infection control (IC) programs are frequently under-resourced, whereas their improvement is considered a pressing issue. Hospital accreditation may have a positive impact on IC program performance. The Japan Council for Quality Health Care (JCQHC) is a hospital accreditation organization that now prescribes broad elements of IC as part of its accreditation standards. METHODS: We sent questionnaire surveys to all teaching hospitals in Japan to characterize the current situation of hospital IC activities and identify the impact of accreditation on IC infrastructure and performance. The self-administered questionnaire that we used was developed based on the JCQHC accreditation standards. Surveys were sent to all institutions in 2004 and again in 2005. RESULTS: Of the 638 hospitals surveyed, 335 (52%) answered in both years. Most IC practitioners in Japanese teaching hospitals were working part time and spent limited hours performing IC duties. Surveillance was poorly implemented in Japan, and IC activities without evidence of effectiveness were widely performed. Surveillance was implemented more frequently in hospitals with adequate IC staffing. Improvement in IC infrastructure and performance between the surveys was larger in the newly accredited hospitals than the others. CONCLUSIONS: Hospital accreditation had a significant impact on hospitals' IC infrastructure and performance.

National hospital infection surveillance on methicillin-resistant Staphylococcus aureus.

National hospital infection surveillances on methicillin-resistant Staphylococcus aureus (MRSA) had been carried out in 1995 and 1996. Recently, in the UK and the USA, the prevalence of MRSA has increased and strict precautions against MRSA are recommended. In Japan, hospital infection rates of MRSA have appeared to be stable in recent years, but a reevaluation is required to confirm this assumption. In a nationwide surveillance, the incidences of MRSA hospital infections per 100 admissions remained stable at between 0.7 and 0.8 from 1999 to 2003, with a tendency towards a slight decline being observed. This study shows that the precautions against MRSA infection in Japan may prove to be an effective preventive measure.

Effects of applying povidone-iodine just before skin closure.

Many surgeons apply povidone-iodine (PVP-I) to the skin around an incision before closing a wound to reduce wound infection rates. However, the effectiveness of this procedure has not been proven. Forty-seven cases of gastric surgery and 60 cases of colorectal surgery performed at Kanto Medical Center between July 2004 and December 2004 were randomly assigned to the group with PVP-I or the group without PVP-I. Wound infection and surgical site infection (SSI) rates were compared between these two groups. Applying PVP-I was effective in eliminating skin contamination, as cultures became negative in all cases after applying PVP-I. However, this study could not demonstrate the reduction of wound infection or SSI in the group with PVP-I, possibly because the number of cases in this study was too small to make a difference. Subcutaneous tissue contamination was considered a more important factor than skin contamination in causing wound infection.

[Evaluation of patient entrance dose rate of interventional X-ray equipment].

Because interventional radiology (IVR) procedures are being performed with increasing frequency, patient X-ray exposure dose for X-ray fluoroscopic and radiographic procedures should not be ignored. In order to avoid excessive X-ray exposure, exposure dose rate limits are specified in the Japanese Industrial Standards (JIS) and by civil law at 50 mGy/min for usual fluoroscopy and 125 mGy/min for high-dose fluoroscopy. In the present study, we examined the difference in patient incident dose rate before and after using an X-ray generator that satisfied the above requirements. For incident dose to the image intensifier (I.I.), we investigated the differences between continuous and pulsed fluoroscopy, the effects of additional filters (Ta: tantalum, Al: aluminum), and the form of the X-ray spectrum. For pulsed fluoroscopy using PMMA (polymethyl-methacrylate), the maximum patient incident dose rates of usual and high-dose fluoroscopy were 59 mGy/min and 151 mGy/min, respectively. With regard to I.I. incident dose, saturation was observed beginning at a PMMA of 20 cm, and the X-ray dose was insufficient. In terms of the difference in patient incident dose rate with Ta and Al filters, the dose rate with the Ta filter was approximately 50% lower than that with the Al filter except for the saturation area. Concerning the X-ray spectrum, it was considered that a Ta filter not only minimizes patient X-ray exposure (because Ta reduces soft X-rays more effectively than Al) but also minimizes scattered X-rays because it filters out hard X-rays, leading to improved image quality. However, the use of the filter is appropriate only when a sufficient I.I. incident dose can be ensured. Specifically, the use of the filter under saturation conditions can lead to deterioration in image quality. Therefore, IVR X-ray systems must be equipped with an appropriate filter for reducing X-ray exposure while maintaining a sufficient I.I. incident dose rate.

Using surveillance data to direct infection control efforts to reduce surgical-site infections following clean abdominal operations in Japan.

We initiated surveillance for surgical-site infections (SSIs) in a Japanese hospital using Centers for Disease Control and Prevention definitions and the approach of the National Nosocomial Infections Surveillance (NNIS) System. Patients were observed following clean and clean-contaminated abdominal operations. SSI rates were higher than those of the NNIS System, but there was a trend toward decreased SSI rates in the latter half of the study period.