Valveless microliter combustion for densely packed arrays of powerful soft actuators.

Existing tactile stimulation technologies powered by small actuators offer low-resolution stimuli compared to the enormous mechanoreceptor density of human skin. Arrays of soft pneumatic actuators initially show promise as small-resolution (1- to 3-mm diameter), highly conformable tactile display strategies yet ultimately fail because of their need for valves bulkier than the actuators themselves. In this paper, we demonstrate an array of individually addressable, soft fluidic actuators that operate without electromechanical valves. We achieve this by using microscale combustion and localized thermal flame quenching. Precisely, liquid metal electrodes produce sparks to ignite fuel lean methane-oxygen mixtures in a 5-mm diameter, 2-mm tall silicone cylinder. The exothermic reaction quickly pressurizes the cylinder, displacing a silicone membrane up to 6 mm in under 1 ms. This device has an estimated free-inflation instantaneous stroke power of 3 W. The maximum reported operational frequency of these cylinders is 1.2 kHz with average displacements of ∼100 µm. We demonstrate that, at these small scales, the wall-quenching flame behavior also allows operation of a 3 × 3 array of 3-mm diameter cylinders with 4-mm pitch. Though we primarily present our device as a tactile display technology, it is a platform microactuator technology with application beyond this one.

Underactuated fluidic control of a continuous multistable membrane.

This work addresses the challenge of underactuated pattern generation in continuous multistable structures. The examined configuration is a slender membrane which can concurrently sustain two different equilibria states, separated by transition regions, and is actuated by a viscous fluid. We first demonstrate the formation and motion of a single transition region and then sequencing of several such moving transition regions to achieve arbitrary patterns by controlling the inlet pressure of the actuating fluid. Finally, we show that nonuniform membrane properties, along with transient dynamics of the fluid, can be leveraged to directly snap through any segment of the membrane.

Microscale Hydrodynamic Cloaking and Shielding via Electro-Osmosis.

We demonstrate theoretically and experimentally that injection of momentum in a region surrounding an object in microscale flow can yield both "cloaking" conditions, where the flow field outside the cloaking region is unaffected by the object, and "shielding" conditions, where the hydrodynamic forces on the object are eliminated. Using field-effect electro-osmosis as a mechanism for injection of momentum, we present a theoretical framework and analytical solutions for a range of geometrical shapes, validate these both numerically and experimentally, and demonstrate the ability to dynamically switch between the different states.

Nonuniform Electro-osmotic Flow Drives Fluid-Structure Instability.

We demonstrate the existence of a fluid-structure instability arising from the interaction of electro-osmotic flow with an elastic substrate. Considering the case of flow within a soft fluidic chamber, we show that above a certain electric field threshold, negative gauge pressure induced by electro-osmotic flow causes the collapse of its elastic walls. We combine experiments and theoretical analysis to elucidate the underlying mechanism for instability and identify several distinct dynamic regimes. The understanding of this instability is important for the design of electrokinetic systems containing soft elements.

Awareness of European practitioners toward uncommon tropical diseases: are we prepared to deal with mass migration? Results of an international survey.

PURPOSE: The recent rise in migration from Africa through the Mediterranean basin into Europe has resulted in an increased incidence of uncommon diseases such as schistosomiasis and genito-urinary tuberculosis, which were previously largely unknown in this region. This study aimed to evaluate the insight of European urologists into diagnosing and managing these disease conditions and to determine whether they were adequately prepared to deal with the changing disease spectrum in their countries. METHODS: A survey including specific questions about the diagnosis and management of 'tropical' urological diseases was distributed among urologists working in Europe and Africa. Multivariate logistic regression models were performed to detect the continent (African or European) effect on knowledge of and insight into tropical urological diseases. RESULTS: A total of 312 surveys were administered. African and European respondents accounted for 109 (36.09%) and 193 (63.91%) respondents, respectively. The multivariate logistic regression analysis demonstrated a significant deficiency in the knowledge of tropical urological diseases in the European cohort compared with the African cohort (p < 0.05). Moreover, in the European cohort, markedly superior knowledge of tropical urological diseases was observed for respondents who had previously worked in a developing country. CONCLUSIONS: Though European urologists are not required to have the same insight as African urologists, they showed a very unsatisfactory knowledge of tropical urological diseases. The experience of working in a developing country could improve the knowledge of European urologists regarding tropical urological diseases.

Penile allotransplantation for penis amputation following ritual circumcision: a case report with 24 months of follow-up.

INTRODUCTION: Ritual circumcision complicated by gangrene is a leading cause of penile loss in young men in South Africa. This deeply rooted cultural tradition is unlikely to be abolished. Conventional reconstructive techniques using free vascularised tissue flaps with penile implants are undesirable in this often socioeconomically challenged group because donor site morbidity can hinder manual labour and vigorous sexual activity might lead to penile implant extrusion. The psychosociological effects of penile loss in a young man are devastating and replacing it with the same organ is likely to produce the maximum benefit. METHODS: We first performed a cadaver-to-cadaver penile transplantation as preparation. After approval from the Human Research Ethics Committee was obtained, we recruited potential recipients. We screened the potential participants for both physical and psychological characteristics, including penile stump length, and emotional suitability for the procedure. A suitable donor became available and the penis was harvested. We surgically prepared the penile stump of the recipient and attached the penile graft. Immunosuppression treatment with antithymyocyte globulin, methylprednisolone, tacrolimus, mycophenolate mofetil, and prednisone were commenced. Tadalafil at 5 mg once per day was commenced after 1 week as penile rehabilitation and was continued for 3 months. We collected on quality-of-life scores (Short Form 36 version 2 [SF-36v2] questionnaires) before surgery and during follow-up and measured erectile function (International Index for Erectile Function [IIEF] score) and urine flow rates at 24 months post transplant. FINDINGS: The warm ischaemia time for the graft after removal was 4 min and the cold ischaemia time was 16 h. The surgery lasted 9 h. An arterial thrombus required urgent revision 8 h after the operation. On post operative day 6, an infected haematoma and an area of proximal skin necrosis were surgically treated. The recipient was discharged after 1 month and first reported satisfactory sexual intercourse 1 week later (despite advice to the contrary). The recipient reported regular sexual intercourse from 3 months after the operation. An episode of acute kidney injury at 7 months was reversed by reducing the tacrolimus dose to 14 mg twice per day. At 8 months after surgery, the patient had a skin infection with phaeohyphomycosis due to Alternaria alternata, which we treated with topical antifungal medication. Quality-of-life scores improved substantially after the operation (SF-36v2 mental health scores improved from 25 preoperatively, to 57 at 6 months and 46 at 24 months post transplant; physical health scores improved from 37 at baseline to 60 at 6 months and 59 at 24 months post-transplant). At 24 months, measured maximum urine flow rate (16·3 mL/s from a volume voided of 109 mL) and IIEF score (overall satisfaction score of 8 from a maximum of 10) were normal, showing normal voiding and erectile function, respectively. INTERPRETATION: Penile transplantation restored normal physiological functions in this transplant recipient without major complications in the first 24 months. FUNDING: Department of Health, Western Cape Government.

Inter-rater reliability in the radiological classification of renal injuries.

INTRODUCTION: Although many radiologists invoke the surgical classification of renal injury proposed by the American Association for Surgery in Trauma (AAST), there has been only limited work on the role of the AAST system as an imaging stratification. The aim was to determine the inter-rater reliability (IRR) amongst radiologists and urologists using the AAST system. METHODS: A 1-year retrospective study of consecutive patients with computed tomography (CT) evidence of renal trauma managed at a Level 1 trauma center. Three radiologists and three urologists independently stratified the presentation CT findings according to the AAST renal trauma classification. Agreement between independent raters and mutually exclusive groups was determined utilizing weighted kappa coefficients. RESULTS: One hundred and one patients were included. Individual inter-observer agreements ranged from 54/101 (53.4%) to 62/101 (61.4%), with corresponding weighted kappa values from 0.61 to 0.69, constituting substantial agreement. Urologists achieved intra-disciplinary agreement in 49 cases (48.5%) and radiologists in 36 cases (35.6%). Six-reader agreement was achieved in 24 cases (23.7%). The AAST grade I injuries had the highest level of agreement, overall. CONCLUSION: The finding of substantial IRR amongst radiologists and urologists utilizing the AAST system supports continued use of the broad parameters of the AAST system, with some modification in specific categories with lower agreement.

Peptidomic discovery of short open reading frame-encoded peptides in human cells.

The complete extent to which the human genome is translated into polypeptides is of fundamental importance. We report a peptidomic strategy to detect short open reading frame (sORF)-encoded polypeptides (SEPs) in human cells. We identify 90 SEPs, 86 of which are previously uncharacterized, which is the largest number of human SEPs ever reported. SEP abundances range from 10-1,000 molecules per cell, identical to abundances of known proteins. SEPs arise from sORFs in noncoding RNAs as well as multicistronic mRNAs, and many SEPs initiate with non-AUG start codons, indicating that noncanonical translation may be more widespread in mammals than previously thought. In addition, coding sORFs are present in a small fraction (8 out of 1,866) of long intergenic noncoding RNAs. Together, these results provide strong evidence that the human proteome is more complex than previously appreciated.

Kinetics of fast changing intramolecular distance distributions obtained by combined analysis of FRET efficiency kinetics and time-resolved FRET equilibrium measurements.

Detailed studies of the mechanisms of macromolecular conformational transitions such as protein folding are enhanced by analysis of changes of distributions for intramolecular distances during the transitions. Time-resolved Förster resonance energy transfer (FRET) measurements yield such data, but the more readily available kinetics of mean FRET efficiency changes cannot be analyzed in terms of changes in distances because of the sixth-power dependence on the mean distance. To enhance the information obtained from mean FRET efficiency kinetics, we combined the analyses of FRET efficiency kinetics and equilibrium trFRET experiments. The joint analysis enabled determination of transient distance distributions along the folding reaction both in cases where a two-state transition is valid and in some cases consisting of a three-state scenario. The procedure and its limits were tested by simulations. Experimental data obtained from stopped-flow measurements of the refolding of Escherichia coli adenylate kinase were analyzed. The distance distributions between three double-labeled mutants, in the collapsed transient state, were determined and compared to those obtained experimentally using the double-kinetics technique. The proposed method effectively provides information on distance distributions of kinetically accessed intermediates of fast conformational transitions induced by common relaxation methods.

Clinical (non-histological) diagnosis of advanced prostate cancer: Evaluation of treatment outcome after androgen deprivation therapy.

Introduction. Transrectal biopsy in suspected adenocarcinoma of the prostate (ACP) may cause significant morbidity and even mortality. A strong association between serum prostate-specific antigen (PSA) and tumour burden exists. If biopsy can be avoided in advanced disease, much morbidity and cost may be saved.Objective. To evaluate the reliability of using PSA and clinical features to establish a non-histological diagnosis of ACP.Methods. Androgen deprivation therapy (ADT) was used in 825 (56.2%) of 1 467 men with ACP. The diagnosis of ACP was made histologically in 607 patients (73.6%) and clinically alone in 218 (26.4%), based on a serum PSA level of >60 ng/ml, and/or clinical evidence of a T3 - T4 tumour on digital rectal examination, and/or imaging evidence of metastases. We compared two randomly selected groups treated with bilateral orchidectomy (BO) based on a clinical-only (n=90) v. histological (n=96) diagnosis of ACP.Results. There was no significant difference between the groups with regard to mean follow-up (26.1 v. 26.8 months), documented PSA relapse (70% v. 67.7%), and patients alive at last follow-up (91.1% v. 95.8%). ZAR1 068 200 (US$1 = ZAR8) was saved by treating men with advanced ACP on the basis of a clinical (non-histological) diagnosis only, and a total of ZAR24 321 000 was saved by using BO instead of luteinising hormone-releasing hormone agonists as ADT.Conclusion. A reliable clinical (non-histological) diagnosis of advanced ACP can be made based on serum PSA and clinical features. This avoids the discomfort and potentially serious complications of biopsy and saves cost.

Preparation of homogeneous samples of double-labelled protein suitable for single-molecule FRET measurements.

Preparation of pure and homogenous site specifically single- and double-labelled biopolymers suitable for spectroscopic determination of structural characteristics is a major current challenge in biopolymers chemistry. In particular, proper analysis of single-molecule Förster resonance energy transfer measurements is based on the spectral characteristics of the probes. Heterogeneity of any of the probes may introduce errors in the analysis, and hence, care must be taken to avoid preparation of inhomogeneous labelled biopolymer samples. When we prepared samples of Escherichia coli adenylate kinase (AK) mutants labelled with either Atto 488 or Atto 647N, the products were spectrally inhomogeneous and the composition of the mixture changed gradually over time. We show here that the inhomogeneity was not a result of variation in the dye interaction with neighbouring side chains. Rather, the slow drift of the spectral characteristics of the probes was a characteristic of an irreversible chemical transformation probably due to the hydrolysis of the succinimide ring of the attached dye into its succinamic acid form. Overnight incubation of the labelled protein in mild basic solution accelerated the interconversion, yielding homogeneous labelled samples. Using this procedure, we obtained stable homogenous AK mutant labelled at residues 142 and 188.

Tracking of thermal microbial shock proteins and genomic variation of Bacillus cereus due to some abiotic stresses.

Bacillus cereus is considered the most potent bacterial strain in terms of the increment in induced proteins during thermal treatment at 52 °C for 90 min. Protein production in food-born microorganism (Bacillus cereus) recovered from contaminated food was investigated in response to heat shock treatment. Bacterial tolerance towards pH, salinity, and temperature at various levels was also investigated. Heat-shock proteins (HSPs) produced when exposed to 52 °C for up to 60 minutes led to significant differences (30%) above the untreated control (37 °C), and the maximum difference was recorded at 52°C at 90 minutes. ISSR detected a higher number of bands/primer than RAPD (13.7 vs. 12.7, respectively), and more polymorphic bands (10.7 vs. 8.4 bands/primer, respectively). The untreated bacterial strain did not grow at pH levels lower than 3, whereas the thermally treated strain grew significantly at pH two. A consistent increase in HSPs was observed, with a gradual increase in salinity of less than 16%. Surprisingly, the gradual increase in temperature did not induce tolerance against higher temperatures. However, a significant growth rate was noticed in response to heat-shocked treatments. The untreated Bacillus cereus demonstrated antibiotic resistance to gentamycin and clindamycin (1.54 and 1.65 cm, respectively), much lower than the corresponding inhibition areas with preheat-treated test pathogen which were recorded (2.37 and 2.49 cm, respectively).

Multistable Metafluid based Energy Harvesting and Storage.

The thermodynamic properties of fluids play a crucial role in many engineering applications, particularly in the context of energy. Fluids with multistable thermodynamic properties may offer new paths for harvesting and storing energy via transitions between equilibria states. Such artificial multistable fluids can be created using the approach employed in metamaterials, which controls macro-properties through micro-structure composition. In this work, the dynamics of such "metafluids" is examined for a configuration of calorically-perfect compressible gas contained within multistable elastic capsules flowing in a fluid-filled tube. The velocity-, pressure-, and temperature-fields of multistable compressible metafluids is studied by both analytically and experimentally, focusing on transitions between different equilibria. The dynamics of a single capsule is first examine, which may move or change equilibrium state, due to fluidic forces. The interaction and motion of multiple capsules within a fluid-filled tube is then studied. It shows that such a system can be used to harvest energy from external temperature variations in either time or space. Thus, fluidic multistability allows specific quanta of energy to be captured and stored indefinitely as well as transported as a fluid, via tubes, at standard atmospheric conditions without the need for thermal isolation.

Powerful, soft combustion actuators for insect-scale robots.

Insects perform feats of strength and endurance that belie their small stature. Insect-scale robots-although subject to the same scaling laws-demonstrate reduced performance because existing microactuator technologies are driven by low-energy density power sources and produce small forces and/or displacements. The use of high-energy density chemical fuels to power small, soft actuators represents a possible solution. We demonstrate a 325-milligram soft combustion microactuator that can achieve displacements of 140%, operate at frequencies >100 hertz, and generate forces >9.5 newtons. With these actuators, we powered an insect-scale quadrupedal robot, which demonstrated a variety of gait patterns, directional control, and a payload capacity 22 times its body weight. These features enabled locomotion through uneven terrain and over obstacles.

Epigenetic inheritance is unfaithful at intermediately methylated CpG sites.

DNA methylation at the CpG dinucleotide is considered a stable epigenetic mark due to its presumed long-term inheritance through clonal expansion. Here, we perform high-throughput bisulfite sequencing on clonally derived somatic cell lines to quantitatively measure methylation inheritance at the nucleotide level. We find that although DNA methylation is generally faithfully maintained at hypo- and hypermethylated sites, this is not the case at intermediately methylated CpGs. Low fidelity intermediate methylation is interspersed throughout the genome and within genes with no or low transcriptional activity, and is not coordinately maintained between neighbouring sites. We determine that the probabilistic changes that occur at intermediately methylated sites are likely due to DNMT1 rather than DNMT3A/3B activity. The observed lack of clonal inheritance at intermediately methylated sites challenges the current epigenetic inheritance model and has direct implications for both the functional relevance and general interpretability of DNA methylation as a stable epigenetic mark.

Significance of histological prostatitis in patients with urinary retention and underlying benign prostatic hyperplasia or adenocarcinoma of the prostate.

OBJECTIVE: To compare the clinical features of patients having urinary retention and benign prostatic hyperplasia (BPH) with those having adenocarcinoma of the prostate (ACP) and to evaluate the significance of histological prostatitis. PATIENTS AND METHODS: The clinical data and histopathology reports of patients with retention admitted to Tygerberg Hospital between September 1998 and June 2007 were evaluated. Statistical analysis was performed with Student's t-test, Mann-Whitney test and Fisher's exact test where appropriate and P < 0.05 was considered to indicate statistical significance. RESULTS: Prostatic histology was available in 405 patients, 204 with BPH and 201 with ACP. Comparing those with BPH and those with ACP showed statistically significant differences in mean age (69.5 vs 71.9 years), serum prostate-specific antigen (PSA) level (18.6 vs 899.5 ng/mL) and histological prostatitis (48 vs 25%) but not duration of catheterization, prostate volume or urinary tract infection (UTI). Comparing those with BPH only and those with BPH plus prostatitis showed significant differences in mean age (71.9 vs 67.1 year) and PSA level (14.6 vs 22.8 ng/mL) but not prostate volume, UTI or duration of catheterization. Comparing those with ACP only and those with ACP plus prostatitis showed significant differences in stage T4 cancer (68.1 vs 35.4%) and PSA level (1123.4 vs 232.4 ng/mL) but not age, prostate volume, UTI or duration of catheterization. CONCLUSIONS: Histological prostatitis was almost twice as common in patients with urinary retention associated with underlying BPH than in patients with ACP, but there was no significant difference in the duration of catheterization, prostatic volume or presence of UTI, suggesting that histological prostatitis more often contributes to the development of retention in patients with underlying BPH than in those with ACP. In patients with BPH, histological prostatitis was associated with urinary retention at a significantly younger age and with higher serum PSA levels. In patients with ACP, histological prostatitis was associated with urinary retention at an earlier stage of cancer.

Prevalence of histological prostatitis in men with benign prostatic hyperplasia or adenocarcinoma of the prostate presenting without urinary retention.

OBJECTIVE: To determine the prevalence of prostatitis on histopathological evaluation of prostatic tissue in men without urinary retention. DESIGN, SETTING AND SUBJECTS: The clinical data and histopathology reports of men seen from January 1999 through March 2009 at our institution were analysed using Student's t-test, the Mann-Whitney test and Fisher's exact test where appropriate. Values were expressed as means, medians and ranges (p<0.05 accepted as statistically significant). OUTCOME MEASURES: Data collected included patient age, duration of lower urinary tract symptoms and hospitalisation, findings on digital rectal examination, prostate volume, haemoglobin concentration, serum creatinine and prostate-specific antigen (PSA) levels, and histological findings. RESULTS: Prostatic tissue of 385 men without urinary retention at presentation was obtained via biopsy (48.3% of cases), transurethral prostatectomy (62.9%), retropubic prostatectomy (6.8%) or radical prostatectomy (28.3%). On histological examination, benign prostatic hyperplasia (BPH) was found to be present in 213 patients (55.3%) and adenocarcinoma of the prostate (ACP) in 172 (44.7%). Histological prostatitis was present in 130 patients (61.0%) with BPH and 51 (29.7%) with ACP (p<0.001). A previous study of 405 men presenting with urinary retention at our institution showed histological prostatitis in 98/204 (48.0%) with BPH and in 51/201 (25.4%) with ACP. The group of men with BPH alone had a significantly lower mean serum PSA at presentation (4.5 ng/ml, range 0.3 - 20.8 ng/ml) compared with the group with BPH and prostatitis (11.2 ng/ml, range 0.2 - 145 ng/ml, p=0.011). The mean PSA level at presentation did not differ significantly between the group with ACP only (40.9 ng/ml, range 0 - 255 ng/ml) and the group with ACP plus prostatitis (1 672 ng/ml, range 0.3 - 38 169 ng/ml, p=0.076). CONCLUSIONS: Among men presenting without urinary retention, histological prostatitis was significantly more prevalent in those with BPH than in those with ACP (61% v. 30%), similar to the previous study of men presenting with retention at our institution, in which histological prostatitis was significantly more prevalent in BPH than in ACP (48% v. 25%). This finding suggests that histological prostatitis is not significantly associated with the causation of ACP or urinary retention. Serum PSA at presentation was significantly higher in the group with BPH plus prostatitis compared with BPH alone, but not in the group with ACP plus prostatitis compared with ACP alone.

Fluid-Driven Traveling Waves in Soft Robots.

Many marine creatures, gastropods, and earthworms generate continuous traveling waves in their bodies for locomotion within marine environments, complex surfaces, and inside narrow gaps. In this work, we study theoretically and experimentally the use of embedded pneumatic networks as a mechanism to mimic nature and generate bidirectional traveling waves in soft robots. We apply long-wave approximation to theoretically calculate the required distribution of pneumatic network and inlet pressure oscillations needed to create desired moving wave patterns. We then fabricate soft robots with internal pneumatic network geometry based on these analytical results. The experimental results agree well with our model and demonstrate the propagation of moving waves in soft robots, along with locomotion capabilities. The presented results allow fabricating soft robots capable of continuous moving waves using the common approach of embedded pneumatic networks and requiring only two input controls.

The role of intra-operative void score during transurethral resection of prostate as a marker of efficacy: a feasibility study.

BACKGROUND: To assess the feasibility of a novel intra-operative void scoring technique. To determine if intra-operative void score (VS) could act as a marker for post-operative success following TURP. METHODS: Fifteen patients undergoing TURP were included in this single-centre feasibility study. All patients had indwelling urinary catheters for recurrent retention due to benign prostatic hyperplasia (BPH). In theatre, immediately before- and after TURP, an intra-operative VS was measured and graded 0-5. Primary outcomes were the feasibility of measuring intra-operative VS and its accuracy in predicting surgical outcome. RESULTS: A combined pre- and post-score with a threshold ≥6 correctly predicted 82% of those who were catheter free (sensitivity) and 100% of those who were not catheter free (specificity) at follow up and the positive predictive value was 100% and negative predictive value 60%. CONCLUSION: Intra-operative void score during TURP is simple, reproducible, fast and requires minimal resources. In TURP it may predict successful outcomes by identifying patients who will be catheter free post-operatively as opposed to those who will be catheter dependent despite the procedure.

A metafluid with multistable density and internal energy states.

Investigating and tailoring the thermodynamic properties of different fluids is crucial to many fields. For example, the efficiency, operation range, and environmental safety of applications in energy and refrigeration cycles are highly affected by the properties of the respective available fluids. Here, we suggest combining gas, liquid and multistable elastic capsules to create an artificial fluid with a multitude of stable states. We study, theoretically and experimentally, the suspension's internal energy, equilibrium pressure-density relations, and their stability for both adiabatic and isothermal processes. We show that the elastic multistability of the capsules endows the fluid with multistable thermodynamic properties, including the ability of capturing and storing energy at standard atmospheric conditions, not found in naturally available fluids.