A Customisable Data Acquisition System for Open-Source Hyperspectral Imaging

Hyperspectral imagers, or imaging spectrometers, are used in many remote sensing environmental studies in fields such as agriculture, forestry, geology, and hydrology. In recent years, compact hyperspectral imagers were developed using commercial-off-the-shelf components, but there are not yet any off-the-shelf data acquisition systems on the market to deploy them. The lack of a self-contained data acquisition system with navigation sensors is a challenge that needs to be overcome to successfully deploy these sensors on remote platforms such as drones and aircraft. Our work is the first successful attempt to deploy an entirely open-source system that is able to collect hyperspectral and navigation data concurrently for direct georeferencing. In this paper, we describe a low-cost, lightweight, and deployable data acquisition device for the open-source hyperspectral imager (OpenHSI). We utilised commercial-off-the-shelf hardware and open-source software to create a compact data acquisition device that can be easily transported and deployed. The device includes a microcontroller and a custom-designed PCB board to interface with ancillary sensors and a Raspberry Pi 4B/NVIDIA Jetson. We demonstrated our data acquisition system on a Matrice M600 drone at a beach in Sydney, Australia, collecting timestamped hyperspectral, navigation, and orientation data in parallel. Using the navigation and orientation data, the hyperspectral data were georeferenced. While the entire system including the pushbroom hyperspectral imager and housing weighed 735 g, it was designed to be easy to assemble and modify. This low-cost, customisable, deployable data acquisition system provides a cost-effective solution for the remote sensing of hyperspectral data for everyone.

Paediatric high-grade osteosarcoma and its prognostic factors: a 10-year retrospective study

INTRODUCTION

This retrospective study was conducted to identify the characteristics of paediatric high-grade osteosarcoma and define its prognostic factors.

METHODS

We identified paediatric patients (aged <19 years at diagnosis) diagnosed with high-grade osteosarcoma from 1 January 2009 to 31 December 2018 in two hospitals in Hong Kong, then retrospectively evaluated their medical records to identify prognostic factors.

RESULTS

In total, 52 patients were included in this study (22 girls, 42.3%). Femoral tumour was the most common form of osteosarcoma. Most patients (78.8%) had localised disease at diagnosis. The lung was the most common site of metastasis. Almost half (n=23, 46.9%) of the patients showed a good response to chemotherapy (ie, chemonecrosis >90%). Most patients (n=40, 80%) underwent limb-salvage surgery. The event-free survival and overall survival rates were 55.8% and 71.2%, respectively. Prognostic factors independently associated with poor event-free survival and poor overall survival were the presence of metastasis at diagnosis, poor tumour chemonecrosis, and the need for amputation.

CONCLUSION

This multicentre review of paediatric high-grade osteosarcoma showed that the baseline patient demographics, event-free survival, and overall survival in Hong Kong were similar to previous findings in other countries. Patients with metastatic disease at diagnosis and poor chemonecrosis had worse survival outcomes. Molecular analyses of genetic abnormalities may help to identify targeted therapies in future studies.

Application of smartphone electrocardiogram

No abstract provided.

Experimental Study on Plasmodium knowlesi Normocyte Binding Protein Xa Region II (PkNBPXaII) for Erythrocyte Binding

Normocyte binding protein Xa (NBPXa) has been implied to play a significant role in parasite invasion of human erythrocytes. Previous phylogenetic studies have reported the existence of three types of NBPXa for Plasmodium knowlesi (PkNBPXa). PkNBPXa region II (PkNBPXaII) of type 1, type 2 and type 3 were expressed on mammalian cell surface and interacted with human and macaque (Macaca fascicularis) erythrocytes. The binding activities of PkNBPXaII towards human and macaque erythrocytes were evaluated using erythrocyte-binding assay (EBA). Three parameters were evaluated to achieve the optimal protein expression of PkNBPXaII and erythrocyte binding activity in EBA: types of mammalian cells, post transfection time and erythrocyte incubation time. COS-7, HEK-293, and CHO-K1 cells showed successful expression of PkNBPXaII, despite the protein expression is weak compared to the positive control. COS-7 was used in EBA. All three types of PkNBPXaII showed rosette formation with macaque erythrocytes but not with human erythrocytes. Future studies to enhance the PkNBPXaII expression on surface of mammalian cells is indeed needed in order to elucidate the specific role of PkNBPXaII in erythrocytes invasion.

An exploratory study of the health harms and utilisation of health services of frequent legal high users under the interim regulated legal high market in central Auckland

AIMS

To explore health problems and the accessing of health services by frequent legal high users under an interim regulated legal market in central Auckland.

METHOD

Frequent legal high users (monthly+) were recruited from outside eight randomly-selected, licensed, legal high stores in central Auckland from 23 April-7 May, 2014. Eligible participants were emailed a unique invitation to complete an on-line survey; 105 completed the survey.

RESULTS

Twenty-seven percent had suffered mental illness during their lifetimes. Eighty percent used synthetic cannabinoids (SC), and 20% 'party pills'. Forty-seven percent of SC users used daily or more often. Other drugs used included alcohol (80%), cannabis (59%), 'ecstasy' (18%) and methamphetamine (15%). Fifty-eight percent of SC users were classified as SC dependent. The most common problems reported from SC use were: insomnia (29%); 'vomiting/nausea' (25%); 'short temper/agitation' (21%); 'anxiety' (21%); 'strange thoughts' (16%); and 'heart palpitations' (14%). The health services most commonly accessed by SC users were: a 'doctor/GP' (9%); 'counsellor' (9%); 'DrugHelp/MethHelp' websites (7%); 'Alcohol & Drug Helpline' (4%); 'ambulance' (3%); 'A&E' (3%); and hospitalisation (3%).

CONCLUSIONS

Frequent use of interim licensed SC products was associated with health problems, including dependency. Further research is required to determine the health risks of these products.

Graphene oxide/polysulfone hollow fiber mixed matrix membranes for gas separation

The application of graphene oxide as a nano-filler in polysulfone asymmetric hollow fiber mixed matrix membranes for CO₂ removal.

Xanthogranulomatous inflammation of terminal ileum: report of a case with small bowel involvement

Xanthogranulomatous inflammation is a rare pathological condition most frequently detected in the kidney and gallbladder. Reported herein is a case of xanthogranulomatous inflammation in a 51-year-old male presenting as a mass-forming lesion in the terminal ileum with mucosal ulceration. Diagnostic laparoscopy followed by ileocecectomy was performed due to intra-operative suspicion of carcinoma of appendix. This is a report of the condition involving the terminal ileum with mucosal ulceration and full-thickness involvement of bowel wall which are uncommon features of xanthogranulomatous inflammation in previously reported lower gastro-intestinal tract lesions.

Thin film nanocomposite embedded with polymethyl methacrylate modified multi-walled carbon nanotubes for CO2 removal

Thin film nanocomposite loaded with milled polymethyl methacrylate grafted multi-walled carbon nanotubes achieved 29%, 47% and 9% increment in CO₂ permeance, CO₂/N₂ and CO₂/CH₄ selectivity respectively compared to its thin film composite counterpart.

Dispersive infrared spectroscopy measurements of atmospheric CO₂ using a Fabry-Pérot interferometer sensor

In this paper, we present the first dispersive infrared spectroscopic (DIRS) measurement of atmospheric carbon dioxide (CO2) using a new scanning Fabry-Pérot interferometer (FPI) sensor. The sensor measures the optical spectra in the mid infrared (3,900 nm to 5,220 nm) wavelength range with full width half maximum (FWHM) spectral resolution of 78.8 nm at the CO2 absorption band (~4,280 nm) and sampling resolution of 20 nm. The CO2 concentration is determined from the measured optical absorption spectra by fitting it to the CO2 reference spectrum. Interference from other major absorbers in the same wavelength range, e.g., carbon monoxide (CO) and water vapor (H2O), was taken out by including their reference spectra in the fit as well. The detailed descriptions of the instrumental setup, the retrieval procedure, a modeling study for error analysis as well as laboratory validation using standard gas concentrations are presented. An iterative algorithm to account for the non-linear response of the fit function to the absorption cross sections due to the broad instrument function was developed and tested. A modeling study of the retrieval algorithm showed that errors due to instrument noise can be considerably reduced by using the dispersive spectral information in the retrieval. The mean measurement error of the prototype DIRS CO2 measurement for 1 minute averaged data is about ±2.5 ppmv, and down to ± 0.8ppmv for 10 minute averaged data. A field test of atmospheric CO2 measurements were carried out in an urban site in Hong Kong for a month and compared to a commercial non-dispersive infrared (NDIR) CO2 analyzer. 10 minute averaged data shows good agreement between the DIRS and NDIR measurements with Pearson correlation coefficient (R) of 0.99. This new method offers an alternative approach of atmospheric CO2 measurement featuring high accuracy, correction of non-linear absorption and interference of water vapor.

Aggressive surgical palliation for advanced girdle tumours

Background:

The surgical management of advanced, incurable, malignant disease presents particular ethical and technical challenges. The clear goal is palliation and the surgical futility must be avoided. This case series presents some particular challenges in end-of-life surgery.

Materials and Methods:

Fifteen patients referred with advanced malignant disease involving a limb girdle were reviewed.

Results:

In one case, a patient pleaded for surgery after initially requesting a delay to seek treatment from a Chinese Traditional Herbalist. The increase in tumour bulk led to problems with surgery and the patient died in a hospital a few weeks later. This case illustrates ‘futility’ not recognized and encountered. The remaining 14 patients exhibited positive palliation with improved quality of dying and appreciation expressed by patients, relatives and staff.

Conclusion:

In selected cases, with a skilled and experienced surgical team, patients with advanced malignant disease can still benefit from aggressive surgical palliation. The margin of error is small between palliation being attempted and futility being achieved. This considerably adds to the challenge of end-of-life surgery.

IS SYMPTOMATOLOGY USEFUL IN DISTINGUISHING BETWEEN CARPAL TUNNEL SYNDROME AND CERVICAL SPONDYLOSIS?

Hand paraesthesia is a common symptom found in patients either with carpal tunnel syndrome or cervical spondylosis. To differentiate between the two conditions, it is important to identify additional diagnostic symptoms. Ninety-two patients with operated carpal tunnel syndrome and 138 patients with spinal surgery for cervical spondylosis were reviewed. After exclusion of cases co-morbid with both cervical spondylosis and carpal tunnel syndrome or other neurological disorders, 44 patients with carpal tunnel syndrome and 41 patients with cervical spondylosis were compared. There were significant differences in the symptomatology between the two groups. In carpal tunnel syndrome, 84% had nocturnal paraesthesia, 82% hand paraesthesia were aggravated by hand activity, and hand pain occurred in 64%. The incidences were only 10%, 7% and 10%, respectively in cervical spondylosis. Neck pain was present in 76% of cervical spondylosis but only in 14% of carpal tunnel syndrome, and lower limb symptoms were present in 44% of cervical spondylosis and only 9% in carpal tunnel syndrome.

A new sesquiterpenoid from the rhizomes of Homalomena sagittifolia

A new sesquiterpenoid, 1α,4β,7β-eudesmanetriol (1), was isolated together with the known compounds 1β,4β,7β-eudesmanetriol (2) and oplopanone (3) from the rhizomes of Homalomena sagittifolia. The structures of these compounds were determined by extensive spectral analyses. The compounds 1 and 2 inhibited growth of Pseudomonas stutzeri with a MIC value of 117 µM when evaluated for antibacterial activity using the minimum concentration assay. Both these compounds showed remarkable activities against acetylcholinesterase enzyme with IC(50) values ranging between 25 and 26 µM. The isolation of these sesquiterpenoids and their biological activities observed in this study support the reported traditional uses of H. sagittifolia for the treatment of microbial related diseases and central nervous system disorders.

Navigation Endoscopic Assisted Tumor (NEAT) surgery for benign bone tumors of the extremities

A novel technique of using both a navigation system and an endoscope in intra-lesional curettage of benign bone tumors enables safe and adequate tumor removal via a minimal access approach. We performed curettage of benign bone tumors in five consecutive patients (4 female, 1 male, mean age 31.4 years) using a commercial CT-based navigation system supplemented by visual guidance through a shoulder arthroscope. The bone defect was filled with bone cement in four patients and with artificial bone substitute in one patient. Mean follow-up time was 8.8 months (range: 7-12 months). Mean duration of surgery was 144 min (range: 120-165 min). Mean wound length of each portal site was 19.5 mm (range: 15-25 mm). All patients could achieve a full range of joint movement and walk unaided at 4 weeks post-surgery. No local recurrence was noted.

Integration of CAD/CAM planning into computer assisted orthopaedic surgery

Modern Computer Aided Design/Modeling (CAD/CAM) software allows complex surgical simulations, but it is often difficult to transfer and execute precisely the planned scenarios during actual operations. We describe a new method of integrating CAD/CAM surgical plans directly into a computer surgical navigation system, and demonstrate its use to guide three complex orthopaedic surgical procedures: a periacetabular osteotomy of a dysplastic hip, a corrective osteotomy of a post-traumatic tibial deformity, and a multi-planar resection of a distal femoral tumor followed by reconstruction with a CAD custom prosthesis.

Focused ion beam characterization of bicomponent polymer fibers

Previous work has shown that focused ion beam (FIB) nanomachining can be effectively utilized for the cross-sectional analysis of polymers such as core-shell solid microspheres and hollow latex nanospheres. While these studies have clearly demonstrated the precise location selection and nanomachining control provided by the FIB technique, the samples studied consisted of only a single polymer. In this work, FIB is used to investigate bicomponent polymeric fiber systems by taking advantage of the component's differing sputter rates that result from their differing physical properties. An approach for cross sectioning and thus revealing the cross-sectional morphology of the polymeric components in a bicomponent polymeric fiber with the island-in-the-sea (I/S) structure is presented. The two I/S fibers investigated were fabricated using the melt spinning process and are composed of bicomponent combinations of linear low density polyethylene (LLDPE) and nylon 6 (PA6) or polylactic acid (PLA) and an EastONE proprietary polymer. Topographical contrast as a result of differential sputtering and the high surface specificity and high signal-to-noise obtained using FIB-induced secondary electron imaging is shown to provide a useful approach for the rapid characterization of the cross-sectional morphology of bicomponent polymeric fibers without the necessity of staining or other sample preparation.

Initial presentation and management of osteosarcoma, and its impact on disease outcome

OBJECTIVE

To evaluate the initial presenting symptoms and management of osteosarcoma in Hong Kong Chinese children, in relation to any possible impact on disease outcomes.

DESIGN

Retrospective study.

SETTING

A tertiary referral centre of bone cancer in a university teaching hospital in Hong Kong.

PATIENTS

All children aged younger than 18 years with a diagnosis of osteosarcoma who received treatment from March 1994 to October 2005.

RESULTS

A total of 51 children were studied. The median age of onset was 13 (range, 3-20) years; 61% were males. The tumours were located in the distal femur and proximal tibia, which accounted for 45% and 22% of the cases, respectively; 24% of patients had metastatic disease at presentation. Swelling (76%) and pain (90%) were the most common presenting complaints. Approximately one third of the patients had a preceding history of trauma. The median duration of initial symptoms to first medical consultation of any sort was 30 (range, 0-360) days. The median time from the first consultation to a definitive diagnosis was 21 (range, 0-350) days; 25% were diagnosed more than 52 days after presentation. Bonesetters were initially consulted by 37% of these patients. From presentation to diagnosis, the median duration was 61 (range, 4-361) days. Analysis of the duration of pre-diagnosis symptoms did not correlate significantly with the development of metastatic disease, response to chemotherapy, feasibility of limb salvage surgery, relapse rates, or survival rates.

CONCLUSIONS

In Hong Kong, initial consultation to bonesetters was common. A relatively long delay in between symptom onset and diagnosis of osteosarcoma was encountered. The public and medical practitioners should be made aware of this disease, especially in adolescents.

catena-Poly[[sodium-di-μ-β-d-glucose] chloride]

The asymmetric unit of the title compound, {[Na(C(6)H(12)O(6))(2)]Cl}(n), contains six glucose mol-ecules, three Na(+) ions and three Cl(-) ions, i.e. three independent {[Na(C(6)H(12)O(6))(2)]Cl} units. Each of these units forms polymeric chains along the c axis. Each Na(+) ion is surrounded by six O atoms from four glucose mol-ecules, forming a distorted octa-hedral geometry. All glucose mol-ecules adopt chair conformations. The constituent units are linked into a three-dimensional framework by O-H⋯Cl and O-H⋯O hydrogen bonds, utilizing all the O-H groups.

Characteristics of ovarian cancer in women residing in Aotearoa, New Zealand: 1993-2004

BACKGROUND

Few studies have compared ovarian cancer rates between different ethnic groups in the same country. The aim of this study was to describe ethnic patterns in the incidence and mortality of ovarian cancer in New Zealand, and to investigate ethnic and socioeconomic differences in the grade and stage of ovarian cancer.

METHODS

Data on all women registered with ovarian cancer on the New Zealand Cancer Registry (1993-2004) were analysed. Population data were taken from the 1996 and 2001 census. Logistic regression was used to estimate associations between ethnicity, deprivation and tumour characteristics.

RESULTS

Age-standardised incidence rates were highest in Pacific women, intermediate in Māori women, and lowest in non-Māori, non-Pacific women. Age-standardised mortality rates showed the same pattern. Ovarian cancer subtypes differed by ethnic group. There was no significant association between socioeconomic deprivation and tumour grade or stage. Age-adjusted models showed that Māori women were more likely to have well-differentiated tumours and less likely to present at a later stage compared to non-Māori, non-Pacific women. These patterns were partly explained by socioeconomic deprivation, and were not apparent for Pacific women.

CONCLUSIONS

Pacific and Māori women experience higher incidence of ovarian cancer and mortality, compared to non-Māori, non-Pacific women. Māori women seemed to have better prognostic factors (local stage and well-differentiated tumours) than non-Māori, non-Pacific women. More work is needed to improve current cancer prevention strategies, particularly in Pacific women.

Differential fadE28 expression associated with phenotypic virulence of Mycobacterium tuberculosis

Ability to persist in human macrophages is central to the virulence of Mycobacterium tuberculosis and is not invariable among various strains. Differential gene expression that is associated with phenotypic virulence may provide additional information of virulent genes involved in the pathogenesis of M. tuberculosis, which is not fully elucidated. Three hypervirulent strains of M. tuberculosis isolated from patients suffering with tuberculous meningitis were shown to grow more rapidly inside human macrophages in a previous study. In the current investigation, expression of 7 mycobacterial genes (fadE28, mce1A, mymA, acr, sigA, sugC, and Rv3723) of these strains during ex vivo macrophage challenge and in vitro acid shock was quantified by real-time PCR. Using rrs gene as a normalisation gene, fadE28 gene exhibited differential gene expression that is associated with phenotypic virulence, whereas the other 6 genes showed indistinguishable expression patterns. Up-regulation of fadE28 gene in the hypervirulent strains may account for virulence by increasing the efficiency of beta-oxidation, which is important for the persistence in macrophages as M. tuberculosis uses fatty acids preferably inside phagosome of macrophages. The fadE28 gene, together with its adjacent genes may also be critical in the process of lipid modification that could facilitate parasitism in human macrophages.

Precision tumour resection and reconstruction using image-guided computer navigation

The use of a navigation system in musculoskeletal tumour surgery enables the integration of pre-operative CT and MRI images to generate a precise three-dimensional anatomical model of the site and the extent of the tumour. We carried out six consecutive resections of musculoskeletal tumour in five patients using an existing commercial computer navigation system. There were three women and two men with a mean age of 41 years (24 to 47). Reconstruction was performed using a tumour prosthesis in three lesions and a vascularised fibular graft in one. No reconstruction was needed in two cases. The mean follow-up was 6.9 months (3.5 to 10). The mean duration of surgery was 28 minutes (13 to 50). Examination of the resected specimens showed clear margins in all the tumour lesions and a resection that was exactly as planned.

Molecular characterization of clinical isolates of Mycobacterium tuberculosis and their association with phenotypic virulence in human macrophages

Among 125 clinical isolates of Mycobacterium tuberculosis collected in Hong Kong and Shanghai, China, between 2002 and 2004, IS6110 typing revealed that 71 strains (57%) belonged to the Beijing family. The intracellular growth of the strains in human peripheral blood monocyte-derived macrophages was measured ex vivo on days 0, 3, 6, and 10. Among all tested strains, three hypervirulent strains showed significant increases in intracellular growth after 10 days of incubation. With an initial bacterial load of 10(4) CFU, most of the clinical isolates and H37Ra (an avirulent strain) exhibited no intracellular survival on day 10, while the three hypervirulent strains together with H37Rv (a virulent strain) showed on average a two- to fourfold rise in CFU count. These three hypervirulent strains belonging to a non-Beijing family were isolated from patients suffering from tuberculosis meningitis. Cytokines secreted by gamma interferon-activated macrophages were measured daily after challenge with selected strains of M. tuberculosis. The levels of tumor necrosis factor alpha were elevated after 24 h of infection among all strains, but the levels were significantly lower among the three hypervirulent strains, whereas interleukin 10 (IL-10) and IL-12 were not detected. Results were concordant with the differential expression of the corresponding cytokine genes in activated macrophages, as monitored by real-time PCR. Our findings highlighted that these three hypervirulent strains may possess an innate mechanism for escaping host immunity, which accounts for their characteristic virulence in patients presenting with a more severe form of disease.

Urine protein-to-creatinine ratio in an untimed urine collection is a reliable measure of proteinuria in lupus nephritis

OBJECTIVE

To evaluate the accuracy of urine protein-to-creatinine (P/C) ratio in an untimed urine specimen as compared with 24 h total protein excretion for measurement of proteinuria in patients with lupus nephritis.

METHODS

Proteinuria in patients with lupus nephritis was assessed by 24 h total protein excretion and spot urine P/C ratio. Correlation and limits of agreement between the two methods were evaluated. The discriminant cutoff values for spot urine P/C ratio in predicting 24 h protein 'threshold' excretion of > or =0.3, > or =0.5, > or =1.0 and > or =3.5 g/day were determined using receiver operating characteristic curves.

RESULTS

A total of 165 samples were available for assessment with 21.8% excluded due to inadequate collection. A strong correlation (r = 0.91, P < 0.0001) was found between spot urine P/C ratio and 24 h urine protein excretion. Bland-Altman plot showed the two tests had acceptable limits of agreement in low level of protein excretion (-0.86 to +0.92 g/day when protein excretion was <2.0 g/day). The limits became wider as the protein excretion increased. The spot urine P/C ratios of 0.45 (sensitivity 0.92; specificity 0.88), 0.7 (0.92; 0.89) and 1.84 (1.0; 0.86) mg/mg reliably predicted 24 h urine total protein equivalent 'thresholds' at > or =0.5, 1.0 and 3.5 g/day.

CONCLUSION

This study supports the recommendation of using spot urine P/C ratio in screening and monitoring proteinuria in patients with lupus nephritis. However, in assessing the exact amount of proteinuria, the urine P/C ratio may have unacceptably wide limits of agreement in high protein excretion range.

Transvenous embolisation of a carotid-trigeminal cavernous fistula

A carotid cavernous fistula is an abnormal communication between the internal carotid artery and the cavernous sinus. Rarely, this communication is associated with a persistent primitive trigeminal artery, with or without a trigeminal artery aneurysm. We report a case of spontaneous carotid-trigeminal cavernous fistula in which the persistent trigeminal artery was shown only on vertebral artery injection. The absence of an associated trigeminal artery aneurysm allowed a transvenous approach for endovascular treatment with coils and complete obliteration of the cavernous fistula.

Application of the mixed venous blood concentration equation in desflurane anesthesia

BACKGROUND

We have previously proposed an equation derived from Fick's law and Lin's concept of effective blood concentration (EBC) to calculate the mixed venous blood concentration (MVBC) of isoflurane. Desflurane has a lower blood/air partition coefficient than isoflurane and, as such, promotes a faster induction and recovery from anesthesia. In this study, we investigated the application of the MVBC equation to predict the MVBC of desflurane.

METHODS

We maintained anesthesia with a fixed inspired concentration (CI) of desflurane (10%) during cardiac anesthesia in 11 patients. In order to measure the real concentrations of desflurane in mixed venous blood, pulmonary arterial blood samples were collected at different time points via a Swan-Ganz catheter for gas chromatographic-mass spectrometric determination. The relationship between the calculated concentrations and the actual blood sample concentrations of desflurane in mixed venous blood was investigated. Lin's EBC method was also used and the results were compared with those of MVBC.

RESULTS

The calculations from our derived MVBC equation and the actual blood concentrations showed a similar kinetic pattern; the concentration levels were approximately the same and correlated well (r = 0.89) during anesthesia. However, the EBC method failed to accurately estimate the actual blood concentrations.

CONCLUSIONS

The results demonstrate that our equation, but not the EBC method, may be useful for estimating pulmonary blood concentrations of desflurane. The clinical significance and the importance of the method merit further investigation.