Esophageal cooling during ablation of persistent atrial fibrillation is associated with improved freedom from arrhythmia at one-year follow up

Background

Various factors influence successful freedom from atrial arrhythmia after pulmonary vein isolation (PVI) with radiofrequency (RF) ablation for the treatment of atrial fibrillation (AF). Lesion transmurality and continuity (as measured by the Continuity Index) are two important factors, and these can be worsened by pauses in RF energy application due to esophageal overheating. Proactive esophageal cooling precludes the need for premature cessation of power, avoiding partially-formed lesions and the need to “hop-scotch” in the left atrium. The resulting improvement in lesion continuity may improve long-term freedom from atrial arrhythmia after PVI, particularly in patients with persistent AF, where more posterior wall ablation is often necessary.

Purpose

Determine differences in freedom from arrhythmia at one year between patients receiving LET monitoring and those receiving esophageal cooling during PVI for persistent AF.

Methods

We reviewed data from two healthcare systems for patient rhythm status at one-year follow up after PVI for the treatment of persistent or long-standing persistent AF. We then determined Kaplan-Meier estimates of freedom from arrhythmia (AF, atrial flutter, and atrial tachycardia), and compared these between patients receiving esophageal cooling and those treated with traditional LET monitoring.

Results

A total of 252 patients received PVI for persistent or long-standing persistent AF and had data available for review. Of these, 148 received LET monitoring (with either a single or multi-sensor temperature probe), and 104 received active cooling with a dedicated esophageal cooling device. Mean age and gender for each group was similar (67.2, range 21 to 88 years, 36% female for LET monitoring, and 67.8, range 32 to 89 years, 30% female for esophageal cooling). KM estimates for freedom from AF at the one-year follow-up were 44.2% for LET monitored patients and 79.3% for actively cooled patients (P=0.01).

Conclusions

Freedom from atrial arrhythmia at one-year after PVI for persistent AF is associated with significant improvement when using active esophageal cooling rather than LET monitoring.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Attune Medical

Arrhythmia recurrence reduction with an active esophageal cooling device during radiofrequency ablation

Funding Acknowledgements

Type of funding sources: None.

Background

As the burden of atrial fibrillation continues to rise with an aging population, there have been contrasting positions on the efficacy of left atrial ablation. While ablation techniques have continued to improve over the past decades, arrhythmia recurrence rates must be further reduced given the burden of ablation on patients. Since continuity of lesion sets has been associated with greater lesion durability, it has been theorized that the use of active esophageal cooling may facilitate greater freedom from arrhythmia.

Purpose

In order to investigate the association between use of active esophageal cooling and arrhythmia recurrence, we performed a multicenter retrospective study of arrhythmia recurrence rates in patients that received active cooling and compared them to those that received luminal esophageal temperature (LET) monitoring.

Methods

In this study, follow up data were collected from patients that underwent pulmonary vein isolation (PVI) at three separate large medical centers. Data were contained in a prospective hospital registry, a prospective physician registry, or the electronic health record, depending on the center. For each patient included, we recorded whether their ablation utilized LET monitoring or active esophageal cooling, along with their rhythm status at 1-year follow up. Rhythm status at follow-up was determined by either electrocardiogram, Holter monitor, or wearable heart rate monitor. Kaplan-Meier (KM) curves were created for freedom-from-arrhythmia at one year comparing those in the LET monitoring group to those in the active cooling group.

Results

Follow up data were collected from 1035 patients. There were 560 patients that received LET monitoring during their original ablation, and 475 patients that underwent active esophageal cooling. KM estimates for freedom-from-arrhythmia at one year were 42% in the LET monitored group and 65% in the actively cooled group (P<.001).

Conclusion

In this large multicenter study, there is a significant increase in freedom-from-arrhythmia at one year follow-up among patients that received active esophageal cooling as compared to those that underwent LET monitoring.

Effect of a proactive esophageal cooling device on procedure length - a multicenter comparison of persistent and paroxysmal atrial fibrillation

Funding Acknowledgements

Type of funding sources: None.

Background

During left atrial ablation for the treatment of atrial fibrillation (AF), effective esophageal protection is essential for reducing or preventing thermal injury. Traditional methods include luminal esophageal temperature (LET) monitoring that lead to frequent pauses in the procedure when temperature alarms alert operators to dangerous temperature levels. While there have been recent studies that demonstrate an association between active esophageal cooling and a reduction in procedure duration regardless of AF type, these retrospective studies have been conducted at single or joint centers which may lead to confounding from other time-saving variables that have changed over time.

Purpose

Consequently, we sought to perform a large-scale multicenter comparison to better elucidate the association between procedure length and the use of active cooling in patients with persistent and paroxysmal atrial fibrillation.

Methods

In this study, we collected data from three large hospital centers, one hospital-maintained registry, one physician-maintained registry, and one through EHR data review and aggregated in groups separated by AF type as well as whether the patients received active cooling or LET monitoring. We then compared median procedure durations in each group.

Results

There were a total of 753 patients included in this study. Of the 360 patients with paroxysmal AF, 179 received active esophageal cooling while 181 underwent LET monitoring. In the persistent AF group with 393 patients, 157 received active esophageal cooling and 236 underwent LET monitoring. Among patients with paroxysmal AF, the median mean procedure duration was 137 minutes in the LET monitored group, and 90 minutes in the actively cooled group with an overall reduction of 47 minutes (P<.001). In patients with persistent AF, the median procedure duration was 148 minutes in the LET monitored group and 94 minutes in the actively cooled group with an overall reduction of 54 minutes (P<.001). The relative reduction as a percent of total procedure time was 34%, and 36%, for paroxysmal and persistent AF cases, respectively.

Conclusion

In this large multicenter review, there is a significant reduction in procedure length when using active esophageal cooling, regardless of AF type.

Radio-Pathomic Maps of Cell Density Identify Brain Tumor Invasion beyond Traditional MRI-Defined Margins

BACKGROUND AND PURPOSE

Currently, contrast-enhancing margins on T1WI are used to guide treatment of gliomas, yet tumor invasion beyond the contrast-enhancing region is a known confounding factor. Therefore, this study used postmortem tissue samples aligned with clinically acquired MRIs to quantify the relationship between intensity values and cellularity as well as to develop a radio-pathomic model to predict cellularity using MR imaging data.

MATERIALS AND METHODS

This single-institution study used 93 samples collected at postmortem examination from 44 patients with brain cancer. Tissue samples were processed, stained with H&E, and digitized for nuclei segmentation and cell density calculation. Pre- and postgadolinium contrast T1WI, T2 FLAIR, and ADC images were collected from each patient's final acquisition before death. In-house software was used to align tissue samples to the FLAIR image via manually defined control points. Mixed-effects models were used to assess the relationship between single-image intensity and cellularity for each image. An ensemble learner was trained to predict cellularity using 5 × 5 voxel tiles from each image, with a two-thirds to one-third train-test split for validation.

RESULTS

Single-image analyses found subtle associations between image intensity and cellularity, with a less pronounced relationship in patients with glioblastoma. The radio-pathomic model accurately predicted cellularity in the test set (root mean squared error = 1015 cells/mm²) and identified regions of hypercellularity beyond the contrast-enhancing region.

CONCLUSIONS

A radio-pathomic model for cellularity trained with tissue samples acquired at postmortem examination is able to identify regions of hypercellular tumor beyond traditional imaging signatures.

Improving Patient Outcomes in the Dual Crises of Climate Change and COVID-19: Proceedings of the Third Annual Clinical Climate Change Meeting, January 8, 2021

The tremendous global toll of the COVID-19 pandemic does not fall equally on all populations. Indeed, this crisis has exerted more severe impacts on the most vulnerable communities, spotlighting the continued consequences of longstanding structural, social, and healthcare inequities. This disparity in COVID-19 parallels the unequal health consequences of climate change, whereby underlying inequities perpetuate adverse health outcomes disproportionately among vulnerable populations. As these two crises continue to unfold, there is an urgent need for healthcare practitioners to identify and implement solutions to mitigate adverse health outcomes, especially in the face of global crises. To support this need, the 2021 Clinical Climate Change Conference held a virtual meeting to discuss the implications of the convergence of the climate crisis and COVID-19, particularly for vulnerable patient populations and the clinicians who care for them. Presenters and panelists provided evidence-based solutions to help health professionals improve and adapt their practice to these evolving scenarios. Together, participants explored the community health system and national solutions to reduce the impacts of COVID-19 and the climate crisis, to promote community advocacy, and foster new partnerships between community and healthcare leaders to combat systemic racism and achieve a more just and equitable society.

Coming Together for Climate and Health: Proceedings of the Second Annual Clinical Climate Change Meeting, January 24, 2020

Climate change is imposing increasingly severe impacts on public health. Addressing these impacts requires heightened awareness of climate-driven health conditions and appropriate clinical practices to manage these conditions. Within this context, the 2nd Annual Clinical Climate Change Conference, held January 24, 2020 at the New York Academy of Medicine, brought together more than 150 allied health practitioners from across the United States for a one-day conference showcasing the state of the science on the climate and health. Eight platform presentations—including a keynote address from Karenna Gore of the Center for Earth Ethics at Union Theological Seminary—covered a range of environmentally induced, climate-related disease areas as well as topics related to environmental justice. Additionally, key workshops engaged participants in the clinical management of climate-related health conditions. Communicating the existing evidence base for climate change-driven impacts on human health is crucial for preparing practitioners to identify and address these impacts. Further partnership between researchers and practitioners to extend and disseminate this evidence base will yield important advancements toward protecting patients and improving health outcomes in an era of climate crisis.

The 2020 report of The Lancet Countdown on health and climate change: responding to converging crises

For the Chinese, French, German, and Spanish translations of the abstract see Supplementary Materials section.

Performance analysis of portable HEPA filters and temporary plastic anterooms on the spread of surrogate coronavirus

The outbreak of COVID-19, and its current resurgence in the United States has resulted in a shortage of isolation rooms within many U.S. hospitals admitting COVID-19-positive cases. As a result, hospital systems, especially those at an epicenter of this outbreak, have initiated task forces to identify and implement various approaches to increase their isolation capacities. This paper describes an innovative temporary anteroom in addition to a portable air purifier unit to turn a general patient room into an isolation space. Using an aerosolization system with a surrogate oil-based substance, we evaluated the effectiveness of the temporary plastic anteroom and the portable air purifier unit. Moreover, the optimal location of the portable unit, as well as the effect of negative pressurization and door opening on the containment of surrogate aerosols were assessed. Results suggested that the temporary anteroom alone could prevent the migration of nearly 98% of the surrogate aerosols into the adjacent corridor. Also, it was shown that the best location of a single portable air purifier unit is inside the isolation room and near the patient's bed. The outcome of this paper can be widely used by hospital facilities managers when attempting to retrofit a general patient room into an airborne infection isolation room.

Sustainability in Dentistry: A Multifaceted Approach Needed

This article provides an introduction to environmentally sustainable dentistry and offers perspectives on managing drivers to reduce carbon emissions and make dentistry more environmentally sustainable. A sustainable world must meet the needs of the present without compromising the ability of future generations to meet their own needs. Global commitment to sustainability and demands for a sustainable world are growing. Within dentistry, travel creates the highest carbon emissions and also contributes to human health damage. Internally, there are a number of ways to reduce impact by decreasing travel and energy use, as well as carefully considering the types of items purchased (and how they are disposed of). Larger dental organizations can influence their suppliers and industry by choosing to purchase from sustainable companies with environmentally friendly products. From an external driver perspective policy, guidance and research are essential. Governments need to reevaluate decontamination policy from an environmental perspective. Decontamination documents need revision to consider both planetary and public health. Dental organizations need to support dental teams in this area. Insurance providers and health care purchasers should review policies to influence the sustainability of dental providers. Sustainability education needs to be considered as part of the curriculum of undergraduate and postgraduate students. Guidance could also be developed for the dental industry to produce sustainable products. Research needs to be prioritized. Identifying hot spots or areas of high environmental contributions using other assessments such as life cycle analysis (LCA) would allow dentistry to identify products or practices that have a disproportionate adverse impact on the environment and might be prioritized for change. This should include an analysis of single-use instruments, chemicals, and products. Building research capacity by training students and creating virtual or physical centers for sustainability is essential. Financial support is needed for priority areas of research.

Temporary mechanical support of left ventricular failure following open heart surgery

Patients coming to open heart surgery with advanced cardiac dysfunction may require mechanical cardiac support to avoid life-threatening low cardiac output in the postoperative period. 15 patients who could not be withdrawn from cardiopulmonary bypass because of low cardiac output were supported with a left heart bypass system (left atrium to ascending aorta). Ten were ultimately separated from the device, 6 were dismissed from the hospital and 4 remain well (the longest 2.6 years postoperative). A major asset of the device is that thoracic reentry is not required when support is discontinued.

Environmental impacts of surgical procedures: life cycle assessment of hysterectomy in the United States

The healthcare sector is a driver of economic growth in the U.S., with spending on healthcare in 2012 reaching $2.8 trillion, or 17% of the U.S. gross domestic product, but it is also a significant source of emissions that adversely impact environmental and public health. The current state of the healthcare industry offers significant opportunities for environmental efficiency improvements, potentially leading to reductions in costs, resource use, and waste without compromising patient care. However, limited research exists that can provide quantitative, sustainable solutions. The operating room is the most resource-intensive area of a hospital, and surgery is therefore an important focal point to understand healthcare-related emissions. Hybrid life cycle assessment (LCA) was used to quantify environmental emissions from four different surgical approaches (abdominal, vaginal, laparoscopic, and robotic) used in the second most common major procedure for women in the U.S., the hysterectomy. Data were collected from 62 cases of hysterectomy. Life cycle assessment results show that major sources of environmental emissions include the production of disposable materials and single-use surgical devices, energy used for heating, ventilation, and air conditioning, and anesthetic gases. By scientifically evaluating emissions, the healthcare industry can strategically optimize its transition to a more sustainable system.

Observing signs of pain in relation to self-injurious behaviour among individuals with intellectual and developmental disabilities

BACKGROUND

Self-injurious behaviour is a chronic condition among people with intellectual and developmental disabilities for which there is no known cure. The pain hypothesis suggests that individuals who engage in self-injury have altered or diminished pain perception. The purpose of the present study was to assess how frequently individuals diagnosed with an intellectual and developmental disability who engage in chronic self-injury displayed non-verbal signs of pain in relation to their self-injury.

METHODS

We videotaped four participants (aged 28-50 years) in their homes during times when they were likely to engage in self-injury. Using continuous recording measures, we coded videotapes for the frequency and duration of self-injury and expressions of non-verbal pain-related behaviours. Sequential analyses were conducted to identify temporal relations between pain-related behaviours and self-injury.

RESULTS

Our data suggest that the existing measures of pain may be systematically related to instances of self-injury. The relationships, however, appear to vary depending on the person who engages in self-injury, the environmental contexts in which the self-injury occurs, and perhaps, the type of self-injury in which the person engages.

CONCLUSIONS

These results support some of the findings of Symons et al. and they raise questions about the blunted nociception hypothesis of self-injury.

Comparative life cycle assessment of disposable and reusable laryngeal mask airways

BACKGROUND

Growing awareness of the negative impacts from the practice of health care on the environment and public health calls for the routine inclusion of life cycle criteria into the decision-making process of device selection. Here we present a life cycle assessment of 2 laryngeal mask airways (LMAs), a one-time-use disposable Unique™ LMA and a 40-time-use reusable Classic™ LMA.

METHODS

In life cycle assessment, the basis of comparison is called the "functional unit." For this report, the functional unit of the disposable and reusable LMAs was taken to be maintenance of airway patency by 40 disposable LMAs or 40 uses of 1 reusable LMA. This was a cradle-to-grave study that included inputs and outputs for the manufacture, transport, use, and waste phases of the LMAs. The environmental impacts of the 2 LMAs were estimated using SimaPro life cycle assessment software and the Building for Environmental and Economic Sustainability impact assessment method. Sensitivity and simple life cycle cost analyses were conducted to aid in interpretation of the results.

RESULTS

The reusable LMA was found to have a more favorable environmental profile than the disposable LMA as used at Yale New Haven Hospital. The most important sources of impacts for the disposable LMA were the production of polymers, packaging, and waste management, whereas for the reusable LMA, washing and sterilization dominated for most impact categories.

DISCUSSION

The differences in environmental impacts between these devices strongly favor reusable devices. These benefits must be weighed against concerns regarding transmission of infection. Health care facilities can decrease their environmental impacts by using reusable LMAs, to a lesser extent by selecting disposable LMA models that are not made of certain plastics, and by ordering in bulk from local distributors. Certain practices would further reduce the environmental impacts of reusable LMAs, such as increasing the number of devices autoclaved in a single cycle to 10 (-25% GHG emissions) and improving the energy efficiency of the autoclaving machines by 10% (-8% GHG emissions). For both environmental and cost considerations, management and operating procedures should be put in place to ensure that reusable LMAs are not discarded prematurely.

Life cycle greenhouse gas emissions of anesthetic drugs

BACKGROUND

Anesthesiologists must consider the entire life cycle of drugs in order to include environmental impacts into clinical decisions. In the present study we used life cycle assessment to examine the climate change impacts of 5 anesthetic drugs: sevoflurane, desflurane, isoflurane, nitrous oxide, and propofol.

METHODS

A full cradle-to-grave approach was used, encompassing resource extraction, drug manufacturing, transport to health care facilities, drug delivery to the patient, and disposal or emission to the environment. At each stage of the life cycle, energy, material inputs, and emissions were considered, as well as use-specific impacts of each drug. The 4 inhalation anesthetics are greenhouse gases (GHGs), and so life cycle GHG emissions include waste anesthetic gases vented to the atmosphere and emissions (largely carbon dioxide) that arise from other life cycle stages.

RESULTS

Desflurane accounts for the largest life cycle GHG impact among the anesthetic drugs considered here: 15 times that of isoflurane and 20 times that of sevoflurane on a per MAC-hour basis when administered in an O(2)/air admixture. GHG emissions increase significantly for all drugs when administered in an N(2)O/O(2) admixture. For all of the inhalation anesthetics, GHG impacts are dominated by uncontrolled emissions of waste anesthetic gases. GHG impacts of propofol are comparatively quite small, nearly 4 orders of magnitude lower than those of desflurane or nitrous oxide. Unlike the inhaled drugs, the GHG impacts of propofol primarily stem from the electricity required for the syringe pump and not from drug production or direct release to the environment.

DISCUSSION

Our results reiterate previous published data on the GHG effects of these inhaled drugs, while providing a life cycle context. There are several practical environmental impact mitigation strategies. Desflurane and nitrous oxide should be restricted to cases where they may reduce morbidity and mortality over alternative drugs. Clinicians should avoid unnecessarily high fresh gas flow rates for all inhaled drugs. There are waste anesthetic gas capturing systems, and even in advance of reprocessed gas applications, strong consideration should be given to their use. From our results it appears likely that techniques other than inhalation anesthetics, such as total i.v. anesthesia, neuraxial, or peripheral nerve blocks, would be least harmful to the environment.

How to dig deeper? Improved enrichment methods for mucin core-1 type glycopeptides

Two different workflows were tested in order to develop methods that provide deeper insight into the secreted O-glycoproteome. Bovine serum samples were subjected to lectin affinity-chromatography both at the protein- and peptide-level in order to selectively isolate glycopeptides with the most common, mucin core-1 sugar. This enrichment step was implemented with either protein-level mixed-bed ion-exchange chromatography or with peptide-level electrostatic repulsion hydrophilic interaction chromatography. Both methods led to at least 65% of the identified products being glycopeptides, in comparison to ≈ 25% without the additional chromatography steps [Darula, Z., and Medzihradszky, K. F. (2009) Affinity enrichment and characterization of mucin core-1 type glycopeptides from bovine serum. Mol. Cell. Proteomics 8, 2515-2526]. In order to improve not only the isolation but also the characterization of the glycopeptides exoglycosidases were used to eliminate carbohydrate extensions from the directly peptide-bound GalNAc units. Consequent tandem MS analysis of the mixtures using higher-energy collision-dissociation and electron-transfer dissociation led to the identification of 124 glycosylation sites in 51 proteins. While the electron-transfer dissociation data provided the bulk of the information for both modified sequence and modification site assignment, the higher-energy collision-dissociation data frequently yielded confirmation of the peptide identity, and revealed the presence of some core-2 or core-3 oligosaccharides. More than two-thirds of the sites as well as the proteins have never been reported modified.

Two-generation reproductive toxicity study of inhaled acrylonitrile vapors in Crl:CD(SD) rats

To assess the effects of acrylonitrile (AN) exposure on reproduction, Sprague-Dawley rats (25/sex/group) were exposed to vapor atmospheres of AN via whole-body inhalation at concentrations of 0, 5, 15, 45 (two offspring generations) and 90 ppm (one offspring generation), 6 h daily, 1 litter/generation, through F2 weanlings on postnatal day 28. After approximately 3 weeks of direct exposure following weaning, exposure of the F1 animals at 90 ppm was terminated due to excessive systemic toxicity in the males. There were no exposure-related mortalities in adult animals, no functional effects on reproduction or effects on reproductive organs, and no evidence of cumulative toxicity or of enhanced toxicity in pregnant and lactating dams or in developing animals. Adult systemic toxicity was limited to body weight and/or food consumption deficits in both sexes and generations (greater in males) at 45 and 90 ppm and increased liver weights in the 90 ppm F0 males and females and 45 ppm F1 males. Neonatal toxicity was expressed by F1 offspring weight decrements at 90 ppm. Clinical signs of local irritation during and immediately following exposure were observed at 90 ppm. Microscopic lesions of the rostral nasal epithelium, representing local site-of-contact irritation, were observed in some animals at 5 to 45 ppm. The no-observed-adverse-effect level (NOAEL) for reproductive toxicity over two generations and neonatal toxicity of AN administered to rats via whole-body inhalation was 45 ppm. The NOAEL for reproduction was 90 ppm for the first generation. The NOAEL for parental systemic toxicity was 15 ppm.

Robotic system for prostate brachytherapy

In contemporary brachytherapy procedures, needle placement at the desired target is challenging for a variety of reasons. A robot-assisted brachytherapy system can potentially improve needle placement and seed delivery, resulting in enhanced therapeutic outcome. In this paper we present a robotic system with 16 degrees of freedom (DOF) (9 DOF for the positioning module and 7 DOF for the surgery module) that has been developed and fabricated for prostate brachytherapy. Strategies to reduce needle deflection and target movement were incorporated after extensive experimental validation. Provision for needle motion and force feedback was included in the system to improve robot control and seed delivery. Preliminary experimental results reveal that the prototype system is sufficiently accurate in placing brachytherapy needles.

Needle insertion force estimation model using procedure-specific and patient-specific criteria

Placement accuracy of different types of surgical needles in soft biological tissues depends on a variety of factors. The needles used for prostate brachytherapy procedures are typically about 200 mm in length and 1.27-1.47 mm in diameter. These needles are prone to deflection and thereby depositing the seeds at a location other than the planned one. Thus tumorous tissues may not receive the planned dose whereas the critical organs may be over-dosed. A significant amount of needle deflection and target movement is related to some procedure-specific criteria and some patient-specific criteria. In this paper we have developed needle insertion force models taking both procedure-specific criteria and patient-specific criteria. These statistical models can be used to estimate the force that the needle will experience during insertion and thereby control the needle to reduce the needle deflection and enhance seed delivery accuracy.

Spatial random tree grammars for modeling hierarchal structure in images with regions of arbitrary shape

We present a novel probabilistic model for the hierarchal structure of an image and its regions. We call this model spatial random tree grammars (SRTGs). We develop algorithms for exact computation of likelihoods and MAP estimates and exact EM updates for model-parameter estimation. We collectively call these algorithms the center-surround algorithm. We use the center-surround algorithm to automatically estimate the ML parameters of SRTGs, classify images based on their likelihood and based on the MAP estimate of the associated hierarchal structure. We apply our method to the task of classifying natural images and demonstrate that the addition of hierarchal structure significantly improves upon the performance of a baseline model that lacks such structure.

Arsenic in Oregon community water systems: demography matters

Recently, the maximum contaminate level (MCL) for arsenic was lowered to 10 microg/L in community water systems (CWS) throughout the United States. In this study, CWS in Oregon were assessed for the occurrence and magnitude of arsenic >10 microg/L between the effective and compliance dates for the new MCL. Ten CWS, with a combined population of 49,395, met the criteria for this study. Arsenic levels above the new MCL ranged from 11-25 microg/L. The demographic characteristics of these systems were queried and considered in the context of risk, exposure and outreach. A disproportionate percent of residents in affected CWS were of Hispanic origin (35%) compared to the statewide average (8%). Residents in these CWS had a lower median household income (20% less than the statewide average), a lower median age (32.5 vs. 36.3) and a higher percent of a second language spoken in the home besides English (34.6% vs. 12.1%) compared to the statewide census. These community characteristics have implications for exposure, risk and outreach associated with the occurrence of arsenic in drinking water. Consequently, demographic parameters are informative for risk management and communication and ultimately, beneficial to the affected public.

Effects of velocity modulation during surgical needle insertion

Precise interstitial intervention is essential for many medical diagnostic and therapeutic procedures. But accurate insertion and placement of surgical needle in soft tissue is quite challenging. The understanding of the interaction between surgical needle and soft tissue is very important to develop new devices and systems to achieve better accuracy and to deliver quality treatment. In this paper we present the effects of velocity (linear, rotational, and oscillatory) modulation on needle force and target deflection. We have experimentally verified our hypothesis that needle insertion with continuous rotation reduces target movement and needle force significantly. We have observed little changes in force and target deflection in rotational oscillation (at least at lower frequency) of the needle.