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"Sam Ita"
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Tokyo pop-up book : a comic adventure with Neko the cat
\"Follow Chico, a young shutterbug, and his mischievous cat Neko as they travel to the world's largest city. It doesn't take long for things to go off course! As Chico nods off, Neko becomes restless and decides to do some sightseeing on her own. Then, the race is on to rescue Neko before she gets lost in the mega-city!\"--Back cover.
Book
Stable carbon isotope and n-alkane distributions in sediment cores from saline and freshwater Gabu lakes, southeast Nigeria: environmental implications
Studies on the utilization of molecular and isotopic proxies for the characterization of organic matter (OM) sources and environmental conditions in lakes have been well-documented globally. Nevertheless, inland lacustrine salt basins remain less well-studied, particularly in tropical sub-Saharan Africa. In this study, we quantified OM sources and evaluated the effects of salt deposit and barite mining on the distribution of n -alkanes in saline and freshwater Gabu lakes sediment cores, southeast Nigeria using elemental, bulk carbon isotope ratios and biomarker distributions. Our results indicate a system inundated with comparable proportions of vascular plant leaf waxes (mean = 56.6%) and submerged/floating macrophytes (mean = 41.1%) with minor contribution from algae/photosynthetic bacteria (mean = 2.3%). The scenario indicates a shallow water system that predominantly preserved long chain n-alkanes derived from vascular plant leaf waxes and macrophytes. The capacity of macrophyte to biosynthesize long chain n-alkanes most likely reflects adaptation of these organisms to partial exposure to the atmosphere. The occurrence in moderate abundance of C17 and C19n-alkanes and the near absence of other low molecular weight (LMW) n-alkanes in the saline lake was linked to the effect of salt stress. The absence of LMW n-alkanes in freshwater lake may be associated with slow barite hydrolysis likely to cause acidification. Our results have demonstrated that long chain n -alkanes of terrestrial and submerged/floating macrophyte origins are better preserved under conditions of low salinity and acidification in inland shallow lakes than those derived from algae/bacteria.
Journal Article
Wide-Area Near-Real-Time Monitoring of Tropical Forest Degradation and Deforestation Using Sentinel-1
The use of Sentinel-1 (S1) radar for wide-area, near-real-time (NRT) tropical-forest-change monitoring is discussed, with particular attention to forest degradation and deforestation. Since forest change can relate to processes ranging from high-impact, large-scale conversion to low-impact, selective logging, and can occur in sites having variable topographic and environmental properties such as mountain slopes and wetlands, a single approach is insufficient. The system introduced here combines time-series analysis of small objects identified in S1 data, i.e., segments containing linear features and apparent small-scale disturbances. A physical model is introduced for quantifying the size of small (upper-) canopy gaps. Deforestation detection was evaluated for several forest landscapes in the Amazon and Borneo. Using the default system settings, the false alarm rate (FAR) is very low (less than 1%), and the missed detection rate (MDR) varies between 1.9% ± 1.1% and 18.6% ± 1.0% (90% confidence level). For peatland landscapes, short radar detection delays up to several weeks due to high levels of soil moisture may occur, while, in comparison, for optical systems, detection delays up to 10 months were found due to cloud cover. In peat swamp forests, narrow linear canopy gaps (road and canal systems) could be detected with an overall accuracy of 85.5%, including many gaps barely visible on hi-res SPOT-6/7 images, which were used for validation. Compared to optical data, subtle degradation signals are easier to detect and are not quickly lost over time due to fast re-vegetation. Although it is possible to estimate an effective forest-cover loss, for example, due to selective logging, and results are spatiotemporally consistent with Sentinel-2 and TerraSAR-X reference data, quantitative validation without extensive field data and/or large hi-res radar datasets, such as TerraSAR-X, remains a challenge.
Journal Article
Source Characterization and Historical Trend of Sedimentary PAHs from Refome Lake, South–South Nigeria
Polycyclic aromatic hydrocarbons (PAHs) released from diverse sources passing through water column carry information into the sediment where they can be used to assess the environmental status of an ecosystem over specified geologic time frame. The vertical distributions of PAHs in two recent sediment cores (RS and RC, 30 cm long) from Refome Lake, South–South Nigeria, were investigated using gas chromatography–mass spectrometry in order to evaluate their sources and historical trends of deposition over the last ca. century. The total PAHs (TPAHs—sum of parent and retene) concentrations ranged from 66.99 ng/g dry weight (dw) at the middle layer of RC core (RC3 10–15 cm) to 182.24 ng/g dw at the near-bottom layer of RS core (RS5 20–25 cm) with a mean of 102.21 ± 24.32 ng/g. The elevated TPAH level at the near-bottom layer of the RS core, corresponding to geologic time-frame ca. 1930–1947, coincided with the period of inhabitation of the European settlers along the lake’s catchments when utilization of coal and/or coal products for domestic/recreational activity was at its peak. A decline in TPAH levels up-cores thereafter reflected the periods of gradual evacuation of inhabitants of the lake area hinterland following the departure of the White after the Nigerian independence in 1960. Evaluation of PAH category according to ring size coupled with data from specific molecular ratios revealed inputs dominated by wood/coal combustion with a moderate contribution from petrochemical/liquid fossil fuel exhaust emissions and a minor diagenetic sources. Principal component analysis result not only distinctively separated RS from RC core samples but also revealed that the RS samples were more impacted by wood/coal combustion emissions than the RC, while liquid fossil fuel exhaust emission dominated the RC over the RS samples. Although short-range eolian transport did play a role in the delivery of PAHs to the lake, localization of source contamination was more important.
Journal Article
Molecular Detection and Clinical Impact of Helicobacter pylori Virulence Genes in Gastric Diseases: A Study in Arequipa, Peru
Background: Helicobacter pylori is a globally prevalent pathogen and a major contributor to gastric diseases, including chronic gastritis, peptic ulcer disease, and gastric cancer. This study investigates the prevalence, distribution, and clinical relevance of its key virulence genes, vacA and cagA, in a Peruvian patient cohort. Materials and Methods: Fifty-one gastric biopsies were collected from patients with a presumptive diagnosis of H. pylori-induced gastritis at Hospital Carlos Alberto Seguín Escobedo in Arequipa, Peru, in March 2024. Two biopsies per patient—one from the antrum and one from the gastric body—were obtained during endoscopy. DNA extraction was performed using the Quick-DNA Fungal/Bacterial Kit (Zymo Research, USA). Molecular identification of H. pylori was conducted via PCR targeting the glmM gene, while the vacA and cagA virulence genes were detected using specific primers. Statistical analyses, including Pearson’s chi-square and Mann–Whitney tests, were applied to assess associations between virulence gene presence and clinical or histopathological variables. Results: Among the gastric biopsies, the vacA gene was detected in 37.3% of samples, while cagA was present in 17.6%. Statistical analysis revealed significant associations between vacA and specific clinical and endoscopic features, including erythematous gastropathy, nodular gastritis, and emetic syndrome, suggesting its localized role in disease pathogenesis. Additionally, the presence of cagA was significantly linked to moderate inflammatory intensity in gastric body biopsies, indicating its association with more severe histopathological outcomes. Chronic gastritis was the most common histopathological finding, with moderate intensity correlating strongly with the presence of virulence genes. Conclusions: These findings highlight substantial regional variability in the distribution and pathogenicity of H. pylori genotypes. This study underscores the importance of incorporating molecular diagnostics into routine clinical practice to improve diagnostic accuracy and inform region-specific therapeutic strategies. This is particularly crucial in endemic regions like Peru, where unique environmental and genetic factors may influence infection dynamics and disease outcomes.
Journal Article
Natural and anthropogenic biomarkers in recent dated sediment cores from Refome Lake, SE Nigeria: environmental implications
Natural and anthropogenic biomarkers characteristics of two recent sediment cores collected toward the shoreline and center of Refome Lake (RS and RC; 30 cm long), southeastern Nigeria, were investigated in order to reconstruct past environmental conditions and asses humans-induced changes on the local ecosystem over the last century. Results from sediment bulk properties such as total organic carbon (TOC; 0.12–0.54%; mean—0.26 ± 0.9%), total nitrogen (TN; 0.01–0.05%; mean—0.03 ± 0.7%) and total inorganic carbon (TIC; 0.03–0.37%; mean—0.14 ± 1.0%) contents as well as TOC/TN (5–25; mean—11.55 ± 1.4) suggested slightly higher contribution from allochthonous over autochthonous organic matter (OM), lowered by low primary production and the characteristic Niger Delta sheltered basin morphology predominated by sandy lithology. Evaluation of molecular proxies such as carbon preference index (CPI
(
C
24
–C
35)
; 1.23–1.74: mean—1.58 ± 0.4), carbon maxima (C
max
—17, 19, 26, 27, 29), long-chain/short-chain hydrocarbons (LHC/SH-C; 0.77–2.25, mean—1.52 ± 0.3) and
P
aq,
(0.21–0.61, mean–0.45 ± 0.3) as well as C
29
/C
27
(0.89–2.67; mean—1.53 ± 0.2) indicated an admixture slightly predominated by microbial OM (algae/bacteria) in the most recent top layer (RC1, 0–5 cm) of RC core and slightly more enhanced terrestrially derived OM in the middle layer (RS4, 15–20 cm) of RS core. The later sediment layer deposited at ca. 1947–1964 coincided with the period of greater wash-in of land-derived OM (associated with tree logging/forest clearing for foot path extension and farmland preparation authorized by the European settlers) occasioned by intense rainfall. The occurrence of gammacerane and 18α-oleanane in low levels in the lower and upper layers revealed trace contamination by petroleum hydrocarbons imported into the Nigerian economy prior to independence in 1960 and utilization of Niger Delta oil after 1960 following departure of the colonial masters (the British), respectively.
Journal Article
Intestinal Microbiota in Children with Anemia in Southern Peru through Next-Generation Sequencing Technology
Knowledge of the sequencing of the 16S rRNA gene constitutes a true revolution in understanding the composition of the intestinal microbiota and its implication in health states. This study details microbial composition through next-generation sequencing (NGS) technology in children with anemia. Anemia is the most frequent hematological disorder that affects human beings. In Peru, it is one of the conditions that presents the most significant concern due to the adverse effects that cause it, such as delayed growth and psychomotor development, in addition to a deficiency in cognitive development.
Journal Article