Displaying publications 1 - 20 of 1701 in total

Abstract:
Sort:
  1. Ng LW, Malhotra R, Lai D, Tai ES, Østbye T
    Asia Pac J Public Health, 2015 Mar;27(2):NP552-61.
    PMID: 23482708 DOI: 10.1177/1010539513479966
    To develop a better understanding of perceived barriers to and ideas for weight loss and maintenance among Malay homemakers in Singapore.
    Matched MeSH terms: Time Factors
  2. Cámara-Leret R, Frodin DG, Adema F, Anderson C, Appelhans MS, Argent G, et al.
    Nature, 2020 08;584(7822):579-583.
    PMID: 32760001 DOI: 10.1038/s41586-020-2549-5
    New Guinea is the world's largest tropical island and has fascinated naturalists for centuries1,2. Home to some of the best-preserved ecosystems on the planet3 and to intact ecological gradients-from mangroves to tropical alpine grasslands-that are unmatched in the Asia-Pacific region4,5, it is a globally recognized centre of biological and cultural diversity6,7. So far, however, there has been no attempt to critically catalogue the entire vascular plant diversity of New Guinea. Here we present the first, to our knowledge, expert-verified checklist of the vascular plants of mainland New Guinea and surrounding islands. Our publicly available checklist includes 13,634 species (68% endemic), 1,742 genera and 264 families-suggesting that New Guinea is the most floristically diverse island in the world. Expert knowledge is essential for building checklists in the digital era: reliance on online taxonomic resources alone would have inflated species counts by 22%. Species discovery shows no sign of levelling off, and we discuss steps to accelerate botanical research in the 'Last Unknown'8.
    Matched MeSH terms: Time Factors
  3. Vincent M, Pometto AL, van Leeuwen JH
    J Microbiol Biotechnol, 2011 Jul;21(7):703-10.
    PMID: 21791956
    Enzymatic saccharification of corn stover using Phanerochaete chrysosporium and Gloeophyllum trabeum and subsequent fermentation of the saccharification products to ethanol by Saccharomyces cerevisiae and Escherichia coli K011 were achieved. Prior to simultaneous saccharification and fermentation (SSF) for ethanol production, solid-state fermentation was performed for four days on ground corn stover using either P. chrysosporium or G. trabeum to induce in situ cellulase production. During SSF with S. cerevisiae or E. coli, ethanol production was the highest on day 4 for all samples. For corn stover treated with P. chrysosporium, the conversion to ethanol was 2.29 g/100 g corn stover with S. cerevisiae as the fermenting organism, whereas for the sample inoculated with E. coli K011, the ethanol production was 4.14 g/100 g corn stover. Corn stover treated with G. trabeum showed a conversion 1.90 and 4.79 g/100 g corn stover with S. cerevisiae and E. coli K011 as the fermenting organisms, respectively. Other fermentation co-products, such as acetic acid and lactic acid, were also monitored. Acetic acid production ranged between 0.45 and 0.78 g/100 g corn stover, while no lactic acid production was detected throughout the 5 days of SSF. The results of our experiment suggest that it is possible to perform SSF of corn stover using P. chrysosporium, G. trabeum, S. cerevisiae and E. coli K011 for the production of fuel ethanol.
    Matched MeSH terms: Time Factors
  4. Whitton C, Ho JCY, Tay Z, Rebello SA, Lu Y, Ong CN, et al.
    Nutrients, 2017 Sep 25;9(10).
    PMID: 28946670 DOI: 10.3390/nu9101059
    The assessment of diets in multi-ethnic cosmopolitan settings is challenging. A semi-quantitative 163-item food frequency questionnaire (FFQ) was developed for the adult Singapore population, and this study aimed to assess its reproducibility and relative validity against 24-h dietary recalls (24 h DR) and biomarkers. The FFQ was administered twice within a six-month interval in 161 adults (59 Chinese, 46 Malay, and 56 Indian). Fasting plasma, overnight urine, and 24 h DR were collected after one month and five months. Intra-class correlation coefficients between the two FFQ were above 0.70 for most foods and nutrients. The median correlation coefficient between energy-adjusted deattenuated FFQ and 24 h DR nutrient intakes was 0.40 for FFQ1 and 0.39 for FFQ2, highest for calcium and iron, and lowest for energy and carbohydrates. Significant associations were observed between urinary isoflavones and soy protein intake (r = 0.46), serum carotenoids and fruit and vegetable intake (r = 0.34), plasma eicosapentaenoic acid and docosahexaenoic acid (EPA + DHA) and fish/seafood intake (r = 0.36), and plasma odd chain saturated fatty acids (SFA) and dairy fat intake (r = 0.25). Associations between plasma EPA + DHA and fish/seafood intake were consistent across ethnic groups (r = 0.28-0.49), while differences were observed for other associations. FFQ assessment of dietary intakes in modern cosmopolitan populations remains feasible for the purpose of ranking individuals' dietary exposures in epidemiological studies.
    Matched MeSH terms: Time Factors
  5. Jaswir I, Shahidan N, Othman R, Has-Yun Hashim YZ, Octavianti F, bin Salleh MN
    J Oleo Sci, 2014;63(8):761-7.
    PMID: 25007748
    Carotenoids are antioxidants with pharmaceutical potential. The major carotenoids important to humans are α-carotene, β-carotene, lycopene, lutein, zeaxanthin, and β-cryptoxanthin. Some of the biological functions and actions of these individual carotenoids are quite similar to each other, whereas others are specific. Besides genotype and location, other environmental effects such as temperature, light, mineral uptake, and pH have been found affect carotenoid development in plant tissues and organs. Therefore, this research investigated the effects of the season and storage periods during postharvest handling on the accumulation of carotenoid in pumpkin. This study shows that long-term storage of pumpkins resulted in the accumulation of lutein and β-carotene with a slight decrease in zeaxanthin. The amounts of β-carotene ranged from 174.583±2.105 mg/100g to 692.871±22.019 mg/100g, lutein from 19.841±9.693 mg/100g to 59.481±1.645 mg/100g, and zeaxanthin from not detected to 2.709±0.118 mg/100g. The pumpkins were collected three times in a year; they differed in that zeaxanthin was present only in the first season, while the amounts of β-carotene and lutein were the highest in the second and third seasons, respectively. By identifying the key factors among the postharvest handling conditions that control specific carotenoid accumulations, a greater understanding of how to enhance the nutritional values of pumpkin and other crops will be gained. Postharvest storage conditions can markedly enhance and influence the levels of zeaxanthin, lutein, and β-carotene in pumpkin. This study describes how the magnitudes of these effects depend on the storage period and season.
    Matched MeSH terms: Time Factors
  6. Dhabali AA, Awang R, Zyoud SH
    J Clin Pharm Ther, 2012 Aug;37(4):426-30.
    PMID: 22081958 DOI: 10.1111/j.1365-2710.2011.01314.x
    WHAT IS KNOWN AND OBJECTIVE: Drug-drug interactions (DDIs) cause considerable morbidity and mortality worldwide and may lead to hospital admission. Sophisticated computerized drug information and monitoring systems, more recently established in many of the emerging economies, including Malaysia, are capturing useful information on prescribing. Our aim is to report on an investigation of potentially serious DDIs, using a university primary care-based system capturing prescription records from its primary care services.
    METHODS: We retrospectively collected data from two academic years over 20 months from computerized databases at the Universiti Sains Malaysia (USM) from users of the USM primary care services.
    RESULTS AND DISCUSSION: Three hundred and eighty-six DDI events were observed in a cohort of 208 exposed patients from a total of 23,733 patients, representing a 2-year period prevalence of 876·4 per 100,000 patients. Of the 208 exposed patients, 138 (66·3%) were exposed to one DDI event, 29 (13·9%) to two DDI events, 15 (7·2%) to three DDI events, 6 (2·9%) to four DDI events and 20 (9·6%) to more than five DDI events. Overall, an increasing mean number of episodes of DDIs was noted among exposed patients within the age category ≥70 years (P=0·01), an increasing trend in the number of medications prescribed (P<0·001) and an increasing trend in the number of long-term therapeutic groups (P<0·001).
    WHAT IS NEW AND CONCLUSION: We describe the prevalence of clinically important DDIs in an emerging economy setting and identify the more common potentially serious DDIs. In line with the observations in developed economies, a higher number of episodes of DDIs were seen in patients aged ≥70 years and with more medications prescribed. The easiest method to reduce the frequency of DDIs is to reduce the number of medications prescribed. Therapeutic alternatives should be selected cautiously.

    Study site: e Universiti Sains Malaysia (USM
    Matched MeSH terms: Time Factors
  7. Hatim A, Habil H, Jesjeet SG, Low CC, Joseph J, Jambunathan ST, et al.
    Hum Psychopharmacol, 2006 Jul;21(5):313-8.
    PMID: 16856220
    In this open-label pilot study, 20 adult patients hospitalized for acute bipolar mania received oral quetiapine as a single evening dose of 200 mg on day 1, increased by 200 mg/day on days 2, 3, and 4 until 800 mg/day taken in 2 divided doses on day 4. From day 5 onward, patients received a flexible total dose of 400-800 mg/day until completion of 3 weeks of treatment. Safety and tolerability were assessed by adverse-event (AE)-related dropouts in week 1, incidence of AEs including EPS, changes in electrocardiogram, and vital signs. Efficacy was assessed using the YMRS, PANSS, and CGI scales. Nineteen of 20 patients (95%) completed the quetiapine rapid titration during week 1. Significant improvement was observed in YMRS, PANSS, and CGI Severity of Illness scores by day 5, and was maintained throughout the study. A reduction of > or = 50% in YMRS score was achieved by 75% of patients by day 7, and maintained to day 21. Overall, 20% of patients discontinued due to AEs. Agitation was the most common cause of AE-related study discontinuation. Thirty-five per cent of patients required dose adjustment due to AEs after rapid dose administration was completed. Most patients tolerated rapid titration of quetiapine to 800 mg/day by day 4 of therapy, with a significant improvement in manic symptoms by day 7 of treatment.
    Matched MeSH terms: Time Factors
  8. Faisham WI, Sulaiman AR, Zulmni W
    Med J Malaysia, 2006 Feb;61 Suppl A:36-9.
    PMID: 17042227
    Femoral neck fracture non-unions often present with significant difficult treatment decision as regards to surgical options and the risk of complication. We present three cases of femoral neck non-union treated with double screw stabilization technique using sliding compression hip screw and anti-rotational screw. The rationale for opting to these simple implants in our setting is discussed.
    Matched MeSH terms: Time Factors
  9. Rohana J, Hasmawati J, Zulkifli SZ
    Singapore Med J, 2007 Mar;48(3):191-4.
    PMID: 17342285
    We report part of the findings of a study conducted to determine the correlation between bone mineral content (BMC) and biochemical bone markers in very low birth weight (VLBW) infants.
    Matched MeSH terms: Time Factors
  10. Soleimani AF, Kasim A, Alimon AR, Zulkifli I
    Pak J Biol Sci, 2008 Sep 01;11(17):2163-6.
    PMID: 19266934
    A trial was conducted to determine the influence of short-term exposure to high ambient temperature at 28 and 35 days of age on deep body temperatures (Tb) and subsequent growth of birds until 42 days of age. A total of 90 day old chicks were reared in stainless steel battery cages and were assigned at random into 18 pens of 5 birds each, with 9 pens containing males and another 9 pens containing females. Three treatment groups, each represented by 3 male and 3 female pens, were represented by T1 without any heat exposure, T2 with heat exposure starting at day 28 and T3 with heat exposure starting at day 35. Heat stress was defined as 180 min exposure to 35 +/- 1 degrees C. Tb and body weights were measured at 35, 37 and 39 days of age immediately following heat exposure. Heat stress resulted in higher Tb and Onset of heat stress at 28 days resulted in significantly lower Tb than onset of heat stress at 35 days. Lower Tb in T2 than T3 permitted recovery in body weight at 42 days. Sexes responded similarly to heat stress.
    Matched MeSH terms: Time Factors
  11. Rogayah J, Zulkifli A
    Med J Malaysia, 2001 Sep;56(3):324-30.
    PMID: 11732078
    A total of 356 doctors responded to a survey on the timing and stability of choice of medical specialty. The majority of doctors made their final decision while working as a medical officer. One hundred (48.5%) of the doctors had made an earlier choice as medical students, 63 (30.6%) during their internship and 43 (20.9%) made their final choice while they were medical officers. Working experience in the specialty was the most important factor in determining final choice of specialty. Advice from consultants/seniors, better financial prospects and parental influence were more important for the male doctors while marriage and family considerations were more important for the female doctors in making their final choice.
    Matched MeSH terms: Time Factors
  12. Said MA, Musarudin M, Zulkaffli NF
    Ann Nucl Med, 2020 Dec;34(12):884-891.
    PMID: 33141408 DOI: 10.1007/s12149-020-01543-x
    OBJECTIVE: 18F is the most extensively used radioisotope in current clinical practices of PET imaging. This selection is based on the several criteria of pure PET radioisotopes with an optimum half-life, and low positron energy that contributes to a smaller positron range. In addition to 18F, other radioisotopes such as 68Ga and 124I are currently gained much attention with the increase in interest in new PET tracers entering the clinical trials. This study aims to determine the minimal scan time per bed position (Tmin) for the 124I and 68Ga based on the quantitative differences in PET imaging of 68Ga and 124I relative to 18F.

    METHODS: The European Association of Nuclear Medicine (EANM) procedure guidelines version 2.0 for FDG-PET tumor imaging has adhered for this purpose. A NEMA2012/IEC2008 phantom was filled with tumor to background ratio of 10:1 with the activity concentration of 30 kBq/ml ± 10 and 3 kBq/ml ± 10% for each radioisotope. The phantom was scanned using different acquisition times per bed position (1, 5, 7, 10 and 15 min) to determine the Tmin. The definition of Tmin was performed using an image coefficient of variations (COV) of 15%.

    RESULTS: Tmin obtained for 18F, 68Ga and 124I were 3.08, 3.24 and 32.93 min, respectively. Quantitative analyses among 18F, 68Ga and 124I images were performed. Signal-to-noise ratio (SNR), contrast recovery coefficients (CRC), and visibility (VH) are the image quality parameters analysed in this study. Generally, 68Ga and 18F gave better image quality as compared to 124I for all the parameters studied.

    CONCLUSION: We have defined Tmin for 18F, 68Ga and 124I SPECT CT imaging based on NEMA2012/IEC2008 phantom imaging. Despite the long scanning time suggested by Tmin, improvement in the image quality is acquired especially for 124I. In clinical practice, the long acquisition time, nevertheless, may cause patient discomfort and motion artifact.

    Matched MeSH terms: Time Factors
  13. Rafiqul IS, Sakinah AM, Zularisam AW
    Appl Biochem Biotechnol, 2015 Jun;176(4):1071-83.
    PMID: 25904039 DOI: 10.1007/s12010-015-1630-2
    Xylose-rich sawdust hydrolysate can be an economic substrate for the enzymatic production of xylitol, a specialty product. It is important to identify the process factors influencing xylitol production. This research aimed to screen the parameters significantly affecting bioxylitol synthesis from wood sawdust by xylose reductase (XR). Enzymatic bioxylitol production was conducted to estimate the effect of different variables reaction time (2-18 h), temperature (20-70 °C), pH (4.0-9.0), NADPH (1.17-5.32 g/L), and enzyme concentration (2-6 %) on the yield of xylitol. Fractional factorial design was followed to identify the key process factors. The screening design identified that time, temperature, and pH are the most significant factors influencing bioxylitol production among the variables with the values of 12 h, 35 °C, and 7.0, respectively. These conditions led to a xylitol yield of 71 % (w/w). This is the first report on the statistical screening of process variables influencing enzyme-based bioxylitol production from lignocellulosic biomass.
    Matched MeSH terms: Time Factors
  14. Mahendran HA, Singam P, Ho C, Goh EH, Tan GH, Zuklifli MZ
    Med J Malaysia, 2012 Apr;67(2):169-72.
    PMID: 22822637 MyJurnal
    Iatrogenic ureteric injuries are rare complications of abdomino-pelvic surgery but associated with high morbidity from infection and possible loss of renal function. A successful repair is related to the timing of diagnosis, site of injury and method of repair. This study was a retrospective review of outcomes of iatrogenic ureteric injury and factors contributing to successful operative repair. Twenty consecutive cases referred to the Urology Unit of the UKM Medical Center during an 11-year period from 1998 to 2009 were reviewed. Thirteen patients were diagnosed intraoperatively and underwent immediate repair. Seven patients had delayed diagnosis but also underwent immediate repair. In our series, there was no significant difference in outcome between injuries diagnosed intraoperatively versus injuries with delayed diagnosis. There was significant difference in the outcomes between methods of ureteric repair where ureter reimplantation via psoas hitch or Boari flap yielded better results than primary end-to-end anastomosis Three patients suffered loss of renal function from unsuccessful ureter repair. We conclude that all iatrogenic ureteric injury should be repaired immediately in the absence of overt sepsis. Ureter reimplantation using a Boari flap or psoas hitch is preferred to the end-to-end anastomosis especially when there is delayed diagnosis
    Matched MeSH terms: Time Factors
  15. Venkatason P, Zubairi YZ, Wan Ahmad WA, Hafidz MI, Ismail MD, Hadi MF, et al.
    BMJ Open, 2019 05 05;9(5):e025734.
    PMID: 31061031 DOI: 10.1136/bmjopen-2018-025734
    OBJECTIVES: Cardiogenic shock (CS) complicating ST-elevation myocardial infarction (STEMI) carries an extremely high mortality. The clinical pattern of this life threatening complication has never been described in Malaysian setting. This study is to investigate the incidence, clinical characteristics and outcome of STEMI patients with CS in our population.

    DESIGN: A retrospective analysis of STEMI patients from 18 hospitals across Malaysia contributing to the Malaysian National Cardiovascular Database-acute coronary syndrome) registry (NCVD-ACS) year 2006-2013.

    PARTICIPANTS: 16 517 patients diagnosed of STEMI from 18 hospitals in Malaysia from the year 2006 to 2013.

    PRIMARY OUTCOME MEASURES: In-hospital and 30 day post-discharge mortality.

    RESULTS: CS complicates 10.6% of all STEMIs in this study. They had unfavourable premorbid conditions and poor outcomes. The in-hospital mortality rate was 34.1% which translates into a 7.14 times mortality risk increment compared with STEMI without CS. Intravenous thrombolysis remained as the main urgent reperfusion modality. Percutaneous coronary interventions (PCI) in CS conferred a 40% risk reduction over non-invasive therapy but were only done in 33.6% of cases. Age over 65, diabetes mellitus, hypertension, chronic lung and kidney disease conferred higher risk of mortality.

    CONCLUSION: Mortality rates of CS complicating STEMI in Malaysia are high. In-hospital PCI confers a 40% mortality risk reduction but the rate of PCI among our patients with CS complicating STEMI is still low. Efforts are being made to increase access to invasive therapy for these patients.

    Matched MeSH terms: Time Factors
  16. Xia W, Tang N, Kord-Varkaneh H, Low TY, Tan SC, Wu X, et al.
    Pharmacol Res, 2020 11;161:105113.
    PMID: 32755613 DOI: 10.1016/j.phrs.2020.105113
    BACKGROUND AND AIM: Previous studies lack consistent conclusions as to whether astaxanthin is actually linked to various health benefits as claimed. Here, we attempt to unravel the association of astaxanthin consumption with selected health benefits by performing a systematic review and meta-analysis.

    METHODS: Online literature search databases including Scopus, Web of Science, PubMed/Medline, Embase and Google Scholar were searched to discover relevant articles available up to 17 March 2020. We used mean changes and SD of the outcomes to assess treatment response from baseline and mean difference, and 95 % CI were calculated to combined data and assessment effect sizes in astaxanthin and control groups.

    RESULTS: 14 eligible articles were included in the final quantitative analysis. Current study revealed that astaxanthin consumption was not associated with FBS, HbA1c, TC, LDL-C, TG, BMI, BW, DBP, and SBP. We did observe an overall increase in HDL-C (WMD: 1.473 mg/dl, 95 % CI: 0.319-2.627, p = 0.012). As for the levels of CRP, only when astaxanthin was administered (i) for relatively long periods (≥ 12 weeks) (WMD: -0.528 mg/l, 95 % CI: -0.990 to -0.066), and (ii) at high dose (> 12 mg/day) (WMD: -0.389 mg/dl, 95 % CI: -0.596 to -0.183), the levels of CRP would decrease.

    CONCLUSION: In summary, our systematic review and meta-analysis revealed that astaxanthin consumption was associated with increase in HDL-C and decrease in CRP. Significant associations were not observed for other outcomes.

    Matched MeSH terms: Time Factors
  17. Oxford J, Berezin EN, Courvalin P, Dwyer DE, Exner M, Jana LA, et al.
    Am J Infect Control, 2014 Apr;42(4):423-5.
    PMID: 24679569 DOI: 10.1016/j.ajic.2013.10.016
    We investigated the survival of a pandemic strain of influenza A H1N1 on a variety of common household surfaces where multiple samples were taken from 4 types of common household fomite at 7 time points. Results showed that influenza A H1N1sw virus particles remained infectious for 48 hours on a wooden surface, for 24 hours on stainless steel and plastic surfaces, and for 8 hours on a cloth surface, although virus recovery from the cloth may have been suboptimal. Our results suggest that pandemic influenza A H1N1 can survive on common household fomites for extended periods of time, and that good hand hygiene and regular disinfection of commonly touched surfaces should be practiced during the influenza season to help reduce transmission.
    Matched MeSH terms: Time Factors
  18. Lee YS, Oh YS, Choi EK, Chern AKC, Jiampo P, Chutinet A, et al.
    Open Heart, 2021 12;8(2).
    PMID: 34857666 DOI: 10.1136/openhrt-2021-001745
    PURPOSE: Dabigatran is a direct thrombin inhibitor approved for stroke prophylaxis in patients with non-valvular atrial fibrillation (NVAF). Real-world data about patient preference, satisfaction and convenience in patients in Asia are not available. The study aimed to explore the perception of patients with newly diagnosed NVAF regarding dabigatran versus vitamin K antagonists (VKAs), when used for stroke prevention.

    PATIENTS AND METHODS: This was a multinational, multicentre, non-interventional study involving 49 sites across 5 countries in South East Asia and South Korea where 934 patients newly diagnosed with NVAF were initiated on either dabigatran (N=591) or VKA (N=343). Data were collected at baseline and over two follow-up visits across 6 months. Treatment satisfaction and patient convenience were evaluated using the Perception on Anticoagulant Treatment Questionnaire-2 (PACT-Q2).

    RESULTS: The mean age of the patients was 65.9±10.4 years, and 64.2% were male. Mean CHA2DS2-VASc score was 2.4±1.5, and mean HAS-BLED score was 1.2±0.9. At baseline, patients initiated on dabigatran had higher stroke risk, bleeding risk, creatinine clearance and proportion of patients with concomitant illnesses compared with patients initiated on VKAs. Treatment convenience was perceived to be significantly better with dabigatran versus VKAs at visits 2 and 3 (p=0.0423 and 0.0287, respectively). Treatment satisfaction was significantly better with dabigatran compared with VKAs at visit 3 (p=0.0300).

    CONCLUSION: In this study, dabigatran is associated with better patient perception in terms of treatment convenience and satisfaction compared with VKAs when used for stroke prevention in newly diagnosed NVAF patients from South East Asia and South Korea.

    TRIAL REGISTRATION NUMBER: NCT02849509.

    PLAIN LANGUAGE SUMMARY: Patient satisfaction with dabigatran versus VKAs in South East Asia. Patients with atrial fibrillation are at high risk of stroke and require anticoagulants for stroke prevention. Two such anticoagulants are dabigatran and VKAs. We wanted to compare the extent of satisfaction and treatment convenience among newly diagnosed patients with atrial fibrillation from the South East Asian region when they were given either dabigatran or VKAs. Consenting patients filled out a standardised questionnaire called the PACT-Q2 over three visits after they were started on either dabigatran (591 patients) or VKAs (343 patients). We found that satisfaction and convenience were significantly higher when patients received dabigatran than when they received VKAs.

    Matched MeSH terms: Time Factors
  19. Hussain H, Yusoff MK, Ramli MF, Abd Latif P, Juahir H, Zawawi MA
    Pak J Biol Sci, 2013 Nov 15;16(22):1524-30.
    PMID: 24511695
    Nitrate-nitrogen leaching from agricultural areas is a major cause for groundwater pollution. Polluted groundwater with high levels of nitrate is hazardous and cause adverse health effects. Human consumption of water with elevated levels of NO3-N has been linked to the infant disorder methemoglobinemia and also to non-Hodgkin's disease lymphoma in adults. This research aims to study the temporal patterns and source apportionment of nitrate-nitrogen leaching in a paddy soil at Ladang Merdeka Ismail Mulong in Kelantan, Malaysia. The complex data matrix (128 x 16) of nitrate-nitrogen parameters was subjected to multivariate analysis mainly Principal Component Analysis (PCA) and Discriminant Analysis (DA). PCA extracted four principal components from this data set which explained 86.4% of the total variance. The most important contributors were soil physical properties confirmed using Alyuda Forecaster software (R2 = 0.98). Discriminant analysis was used to evaluate the temporal variation in soil nitrate-nitrogen on leaching process. Discriminant analysis gave four parameters (hydraulic head, evapotranspiration, rainfall and temperature) contributing more than 98% correct assignments in temporal analysis. DA allowed reduction in dimensionality of the large data set which defines the four operating parameters most efficient and economical to be monitored for temporal variations. This knowledge is important so as to protect the precious groundwater from contamination with nitrate.
    Matched MeSH terms: Time Factors
  20. Stephenson NL, Das AJ, Condit R, Russo SE, Baker PJ, Beckman NG, et al.
    Nature, 2014 Mar 6;507(7490):90-3.
    PMID: 24429523 DOI: 10.1038/nature12914
    Forests are major components of the global carbon cycle, providing substantial feedback to atmospheric greenhouse gas concentrations. Our ability to understand and predict changes in the forest carbon cycle--particularly net primary productivity and carbon storage--increasingly relies on models that represent biological processes across several scales of biological organization, from tree leaves to forest stands. Yet, despite advances in our understanding of productivity at the scales of leaves and stands, no consensus exists about the nature of productivity at the scale of the individual tree, in part because we lack a broad empirical assessment of whether rates of absolute tree mass growth (and thus carbon accumulation) decrease, remain constant, or increase as trees increase in size and age. Here we present a global analysis of 403 tropical and temperate tree species, showing that for most species mass growth rate increases continuously with tree size. Thus, large, old trees do not act simply as senescent carbon reservoirs but actively fix large amounts of carbon compared to smaller trees; at the extreme, a single big tree can add the same amount of carbon to the forest within a year as is contained in an entire mid-sized tree. The apparent paradoxes of individual tree growth increasing with tree size despite declining leaf-level and stand-level productivity can be explained, respectively, by increases in a tree's total leaf area that outpace declines in productivity per unit of leaf area and, among other factors, age-related reductions in population density. Our results resolve conflicting assumptions about the nature of tree growth, inform efforts to undertand and model forest carbon dynamics, and have additional implications for theories of resource allocation and plant senescence.
    Matched MeSH terms: Time Factors
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links