Search Results (169)

Although interior-point methods (IPMs) have transformed mathematical programming since 1984, the original projective Karmarkar algorithm is rarely documented step by step on reproducible engineering examples that combine algorithmic transparency with real resource allocation constraints. This article therefore does not propose a new variant of Karmarkar’s algorithm; rather, its scientific contribution is the reproducible MATLAB implementation, canonical-form conversion, and comparative validation of the original projective method against the revised Simplex method and Barnes’ affine scaling variant in two engineering settings. The case studies are (i) the minimum-weight plastic design of a rigid frame with seven candidate plastic hinge locations and six collapse mechanisms and (ii) the optimal allocation of crop patterns in the Caplina Valley (Tacna, Southern Peru), an arid irrigated system with an irrigated command area of 1253 ha, monthly labor availability of 22,239 jornales, and water availability derived from Caplina River discharges at 75% persistence. For Case I, the algorithm reached F = 1.001 in the normalized dual space, which corresponds to F = 4.251 in the original structural objective after applying the scaling factor 17/4; relative to the analytical optimum F* = 4.25, this gives |4.251 − 4.25|/4.25 = 2.4 × 10⁻⁴ after 20 iterations. For Case II, the model yielded the maximum net production value of USD 703,135.92, allocating 948.47 ha among 12 crops while satisfying water, labor, market, and land constraints. The double validation confirms the algorithm’s strictly interior trajectory, polynomial-time rationale, and transparent internal parameters (α = 0.7968, ε = 10⁻⁸), making the implementation a reproducible benchmark for educational use and for future AI–operations research hybrid solvers in regions with limited access to commercial optimization software. Full article

Starch-degrading enzymes are key biocatalysts in industrial applications, particularly when derived from thermophilic microorganisms with potential to operate under elevated temperatures. In this study, three recombinant starch-degrading enzymes were heterologously produced, purified, and biochemically characterized: an α-amylase from Geobacillus kaustophilus, and an α-glucosidase and a type I pullulanase from Geobacillus sp. G4, a thermophilic strain isolated from a geothermal field in southern Peru. The three enzymes were successfully expressed in soluble form in Escherichia coli and purified by one-step affinity chromatography. Biochemical characterization showed that α-glucosidase and α-amylase displayed optimum activity at pH 6–7, whereas pullulanase exhibited a broader pH profile, retaining high activity up to pH 9. All three enzymes reached maximum activity at 60 °C, although their thermal stability profiles differed markedly, with pullulanase showing the highest thermostability. Metal ion assays revealed enzyme-dependent effects, with pullulanase being stimulated by Ca²⁺ and Mg²⁺, while α-amylase and α-glucosidase showed limited responses to divalent ions. Kinetic analysis using soluble potato starch indicated that α-amylase had the most favorable catalytic profile, with the lowest K_m and the highest catalytic efficiency among the three enzymes. Functional hydrolysis assays demonstrated that all enzymes were active on soluble starch and pretreated potato peel, while the enzymatic mixture consistently released the highest concentration of reducing sugars. These results expand the biochemical knowledge of thermophilic amylolytic enzymes from Geobacillus and support their potential use in future enzymatic systems for the conversion of starch-rich residues. Full article

The study investigates the three-dimensional architecture and thermal structure of the Central Andes in centralsouthern Peru, highlighting the interplay between basement structure, Moho geometry, slab configuration, and thermal properties. Basement structural highs and lows acted as zones of weakness that localized deformation during Andean shortening. The Moho exhibits significant lateral heterogeneity, reflecting the combined effects of subduction processes, crustal shortening, magmatic underplating, and lower crustal flow or delamination. Its geometry provides key constraints on crustal thickness, seismic structure, and lithospheric dynamics. The subducting Nazca Plate shows strong along-strike variations in dip and continuity, influenced by plate kinematics and features such as the Nazca Ridge. These variations control mantle wedge development, arc magmatism, and deformation patterns in the overriding plate, contributing to the segmentation of the Andes. Steepslab segments promote mantle melting and volcanic activity, whereas flat-slab regions suppress magmatism. Consistent with these tectonic controls, Qs values increase from northwest to southeast, reflecting a transition from flat-slab conditions with low heat flow and limited geothermal activity to steep subduction zones characterized by active magmatism, elevated heat flow, and significant geothermal potential. This spatial variation underscores the strong coupling between slab geometry, thermal structure, and surface geothermal expression. Full article

A study of agricultural yield sensitivity in Peru to climate variations is conducted from 1961 to 2024 to identify climate drivers and statistical tools for early warning and risk management. The statistical basis is year-on-year change in standardized crop yield rate (CYR) across the southeastern highlands of Peru 7–15° S, 70–77° W. Crops favoring La Nina include citrus, cotton, fruit, and sugar-cane. Based on temporal and spatial correlation and composite analysis, our findings indicate that (i) east Pacific and Caribbean sea temperatures and Atlantic upper winds provide advance warning signals of CYR fluctuations; (ii) during El Niño, the subtropical jet subsides over the Peruvian highlands, raising temperatures and lowering humidity; (iii) during La Niña, cooler temperatures conspire with rising motion and beneficial rains; and (iv) CYR fluctuations account for 26% of macro-economic variance, ~$66 B at the current value. Bringing technological information to agricultural decision making will improve resilience and help meet the twin challenges of a growing population and changeable climate. Adaptive measures are suggested to take advantage of Southern Oscillation’s influence on austral summer weather and subsequent annual crop yield. Full article

This study considers ocean–atmosphere influences on marine productivity over the shelf of Peru. Annual fish catch since 1961 and monthly satellite phytoplankton fluorescence (FLH) since 1997 in the area 7–14 S, 80–76 W provide a basis for statistical evaluation of environmental indicators from reanalysis fields. Monthly FLH is correlated with the year-on-year change in (anchovy) fish catch, wherein the autumn season (Mar–Aug) shows optimal association. The temporal record of FLH is regressed onto various fields, and the upper and lower 10 years are identified for composite analysis. Statistical results link the Southern Oscillation to wind patterns and oceanic response, wherein greater anchovy catch tends to follow La Niña. A case study is made of the change from El Niño in 2023 to La Niña in 2024. Composites indicate that cyclonic wind vorticity spreads phytoplankton across the Peruvian shelf under La Niña, resulting in a 33% increase in fluorescence from 0.26 to 0.39. Full article

Water-related ritual practices constitute a central axis through which many Andean communities articulate cosmology, social organization, and collective identity. This study examines the Fiesta del Agua (Layimama), an ancestral ritual cycle celebrated in the inter-Andean valley of Ticsani (Moquegua, southern Peru), focusing on its symbolic structure, social roles, and implications for water governance and cultural continuity. Using a qualitative, interpretive research design based on documentary analysis of ethnographic, historical, and anthropological sources, the study analyzes how ritual practices surrounding water function as mechanisms of social cohesion, moral regulation, and symbolic management of a shared natural resource. The findings show that the Fiesta del Agua operates as a cyclical system composed of four interrelated stages (preparation, ritual performance, festive redistribution, and communal closure) through which water is sacralized as an axis mundi linking cosmology, agricultural production, and social prestige. Far from being a residual tradition, the festival actively reproduces collective identity, regulates communal access to water, and integrates Andean cosmology with Catholic symbolism through dynamic forms of religious syncretism. The article argues that the ritual management of water in Ticsani represents a culturally embedded governance system whose documentation and protection are essential in contexts of increasing hydrosocial stress and cultural erosion, indicating social, ecological, and political relevance of the findings and contributing to broader debates on human–environment relations, intangible cultural heritage, and the role of ritual in sustaining communal resource management. Full article

Background/Objectives: Colorectal cancer (CRC) is a leading cause of cancer-related mortality worldwide. Emerging evidence highlights the role of the gut microbiota in the development and progression of CRC. Microbial dysbiosis is hypothesized to contribute to chronic inflammation through a variety of mechanisms, such as the production of free radicals, which induce mutagenesis and immune dysregulation in the host, ultimately leading to diseases such as cancer. Methods: Tumor tissue samples or healthy mucosa tissue were collected for bacterial DNA extraction. The V3–V4 region of the 16S rRNA gene was amplified and sequenced using the Illumina MiSeq platform. Bioinformatics analysis was performed with QIIME2, including quality control, DADA2 denoising, alpha and beta diversity calculation, and taxonomic classification using the SILVA database. Results: Differences in microbial composition were observed between groups. The healthy controls exhibited high relative abundances of beneficial genera such as Faecalibacterium, Bacteroides, and Asteroleplasma, whereas the patients with CRC showed enrichment of atypical genera including Novosphingobium, Bradyrhizobium, and Undibacterium. Alpha diversity was lower in the CRC group, and clear clustering by group was observed in the beta diversity analysis. LEfSe analysis identified potential bacterial biomarkers associated with CRC at both the species and genus levels. Conclusions: The findings of this study support the hypothesis that colorectal cancer is associated with distinct alterations in gut microbiota composition, such as an increase in the Novosphingobium genus and a decrease in the Bacteroides genus. An exploratory description of these microbial profiles may aid in the development of microbiome-based diagnostic and therapeutic strategies and contribute to current knowledge of the role of the gut microbiota in CRC in southern Peru. Full article

Background/Objectives: The coronavirus disease 2019 (COVID-19) pandemic profoundly disrupted global respiratory virus circulation, with sharp declines during 2020–2021, followed by a resurgence after the relaxation of public health measures. In South America, post-pandemic respiratory virus dynamics remain insufficiently characterized, particularly in ecologically diverse regions. Arequipa, a high-altitude city in southern Peru, has unique environmental conditions, including marked seasonal temperature variability, that may influence viral transmission. Methods: We performed a cross-sectional analysis of 21,784 nasopharyngeal swabs collected from symptomatic patients at four major hospitals between June 2021 and September 2023. All samples were tested for SARS-CoV-2 by RT-qPCR. Because routine screening for other respiratory viruses was implemented only in SARS-CoV-2-negative cases during the study period, a subset of SARS-CoV-2-negative samples was subsequently analyzed for influenza A virus (IAV), influenza B virus (IBV), and respiratory syncytial virus (RSV) using VIASURE assays. Viral circulation patterns were evaluated by year, month, and epidemiological week. Meteorological data were obtained from the SENAMHI–La Pampilla station. Logistic regression models were used to assess epidemiological and climatic predictors of viral detection. Results: SARS-CoV-2 positivity declined from 20.0% in 2021 to 8.8% in 2023. Conversely, detection of other respiratory viruses among SARS-CoV-2-negative samples increased from 0.8% in 2021 to 29.0% in 2023 (p < 0.01). Temporal increases in detection were observed during 2022–2023, particularly for IAV and RSV. In exploratory analyses, calendar year and relative humidity were associated with IAV and RSV detection, while age and temperature variables were associated with IBV. Conclusions: Climatic and demographic variables were associated with changes in viral detection for IAV, IBV, and RSV during the post-pandemic transition period in Arequipa. These findings describe patterns of viral detection within SARS-CoV-2-negative symptomatic patients and should be interpreted as surveillance-based observations rather than population-level estimates. Strengthened integrated epidemiological and genomic surveillance will be essential for vaccine planning and outbreak preparedness in the post-pandemic era. Full article

High Andean lagoons in southern Peru have critical hydrological and ecological functions; however, long-term time series integrating trophic, integral quality, and metal contamination metrics to support adaptive management are lacking. A total of 1846 records (2015–2024) from four systems (3100–4600 m a.s.l.) were analyzed using seven indices assessing trophic status (TSItsr, TRIX), general water quality (OWQI, WQIHA, CCME-WQI), and metal contamination (HPI, CD). Temporal trends were assessed using Mann–Kendall and Theil–Sen slope; spatial heterogeneity using Kruskal–Wallis and Dunn–Bonferroni comparisons; controlling factors using distance-based redundancy analysis (999 permutations); and functional typology using Ward’s hierarchical clustering on Z-standardized data. 93% of the series lacked monotonic trends (52/56 lagoon–stratum × index combinations), demonstrating high interannual stability; spatial variance was marked (ε² = 0.73 in CCME-WQI). Distance-based redundancy analysis (db-RDA) explained 24.6% of total variability, with lake identity as the dominant driver (~45%), followed by temporal change (~8%). Four functional archetypes emerged, including a metal-eutrophic hotspot (HPI ≈ 213; CD ≈ 19) and recovering reservoirs with intermediate water quality indicators. Joint thresholds (TSItsr ≥ 60 + HPI ≥ 100) establish early-warning criteria, with Paucarani (HPI = 213) approaching the critical domain where metal-driven stress may facilitate cyanobacterial dominance. Systems show temporal resilience but strong spatial divergence induced by local pressures. The proposed typology and thresholds provide an operational basis for early warnings and prioritization of remediation actions in high-mountain ecosystems subject to increasing anthropogenic stress. Full article

This study analyzes the evolution of rural welfare vulnerability among agricultural households in Peru under the influence of extreme climate events, particularly those associated with the El Niño–Southern Oscillation. The research employs a Socio-Climatic Vulnerability Index (SCVI) constructed from microdata of the National Household Survey (ENAHO) covering the period 2000–2018. Using a longitudinal and territorial perspective, the study evaluates how climate shocks affect household welfare dynamics across Peru’s major geographic regions. The results show that extreme weather events systematically increase rural vulnerability in the years they occur, followed by partial recovery in subsequent periods, indicating temporary but recurrent welfare disruptions. Significant regional heterogeneity is observed. Coastal departments exhibit increasing vulnerability linked to hydro-meteorological exposure and rapid territorial expansion. The Andean region shows the highest and most volatile vulnerability levels due to geographic isolation, infrastructure constraints, and persistent socioeconomic inequalities. Amazonian regions present relatively lower initial vulnerability but display gradual increases associated with climate variability and limited connectivity. Decomposition of the SCVI reveals that improvements in demographic and educational conditions contribute positively to resilience, whereas the productive-economic dimension remains highly sensitive to climatic shocks. Although agricultural households demonstrate adaptive responses and coping strategies, structural gaps hinder full welfare recovery. These findings highlight the need for territorially differentiated climate adaptation policies that strengthen human capital, diversify rural livelihoods, and improve institutional support to enhance long-term resilience in vulnerable rural communities. Full article

Tuberculosis (TB) remains a major public health challenge in Peru, where interindividual variability in treatment response and drug-induced hepatotoxicity may be influenced by host genetic background. This study aimed to characterize clinically relevant polymorphisms in NAT2, CYP2E1, and SLCO1B1 in a cohort of TB patients from Southern Peru, a genetically underrepresented Andean population. Thirty-five adults receiving first-line therapy (isoniazid and rifampicin) underwent targeted Sanger sequencing of key functional variants among these three genes. NAT2 acetylator phenotypes were predominantly intermediate (68.6%), followed by rapid (20%) and slow (11.4%) profiles, with high minor allele frequencies for rs1041983 and rs1801280. CYP2E1 functional promoter variants were infrequent, whereas SLCO1B1 exhibited notable allelic heterogeneity, suggesting potential variability in rifampicin transport. Comparative analysis with previously reported Peruvian data revealed regional differences in acetylator distribution, supporting population-specific pharmacogenomic stratification. Although clinical toxicity outcomes were not evaluated, the high prevalence of reduced acetylation genotypes suggests a substantial proportion of patients may benefit from genotype-informed isoniazid dosing strategies. These findings provide foundational data for implementing precision medicine approaches using affordable and targeted technologies in TB management within Andean populations and support the integration of pharmacogenomics into national TB control programs. Full article

The pronounced heterogeneity of high-Andean soils constitutes a critical constraint to the sustainable productivity of quinoa in southern Peru, where current yields (1.6 t ha⁻¹) remain well below potential (>5 t ha⁻¹). This study aimed to develop a spatially predictive model of a weighted soil quality index (SQIw), the edaphic supply of nitrogen (N), phosphorus (P) and potassium (K), and the agricultural gypsum requirement by integrating edaphoclimatic covariates through regression–kriging. A total of 198 quinoa-cultivated soil samples were analysed; a minimum data set (MDS) was defined using correlation and principal component analyses, and regression–kriging was applied to map SQIw and the variables of interest. The MDS comprised electrical conductivity (EC), organic matter (OM), available P, exchangeable Na, sand, clay, and effective cation exchange capacity (ECEC); exchangeable Na (Wi = 0.160) and available P (Wi = 0.158) received the largest weights in the SQIw. SQIw values ranged from 0.22 to 0.84 and supported a five-class soil quality taxonomy; spatial modelling revealed a dominance of moderate-quality soils across the territory (85.21% of the agricultural area, 13,461.19 ha). The model achieved R² = 0.56, RMSE = 0.05, and MAE = 0.04 for SQIw. Most of the area (12,175.65 ha; 77%) exhibited an intermediate gypsum requirement (9.73–14.33 t ha⁻¹). Nitrogen and phosphorus showed the greatest territorial limitations, whereas potassium was largely non-limiting (84.82–570.17 kg ha⁻¹). These results indicate that sodicity and N–P deficiencies are the primary functional constraints; the generated maps enable prioritisation of gypsum amendments and targeted variable-rate fertilisation strategies to optimise the sustainability of quinoa production in the Altiplano. Full article

This study investigates the extreme wave event that caused damage to the main breakwater at Chancay Port, Peru, on 24 August 2025 (the 824 event), through high-resolution nested numerical wave simulations. The research reveals the underlying mechanisms and causation of the damage. Results indicate that the extreme waves originated from a powerful storm in the Southern Pacific’s Roaring Forties around 20 August. The storm generated long-period swell that propagated to Chancay Port, resulting in significant wave heights of 4.2–4.4 m offshore, exceeding the 475-year return period design standard and ranking as the most severe wave event in the past 30 years. Localized modeling further demonstrates that the swells induced nonlinear transformations in front of the breakwater, with wave heights reaching up to 7 m along the structure and generating complex standing waves near the bend. Comprehensive analysis concludes that the damage was caused by the combined effects of this rare extreme remote swell and localized hydrodynamic interactions with the breakwater. Full article

Groundwater is a critical resource in the arid Chili River sub-basin (3246 km²) in Arequipa, southern Peru, yet the aquifer systems, their recharge mechanisms, and chemical evolution remain poorly characterized. This study integrates hydrogeological mapping, major-ion hydrochemistry (31 samples from springs and wells), and stable-isotope tracing (δ¹⁸O and δ²H, 11 sources) to delineate aquifer types, groundwater flow systems, and recharge dynamics across an elevation gradient of 2000–4000 m a.s.l. Three principal aquifer groups were identified: unconsolidated porous aquifers beneath the Arequipa urban area, fracture-controlled volcanic aquifers associated with the Chachani, Misti, and Pichupichu volcanic complexes, and sedimentary fractured aquifers of the Yura Group. Piper and Stiff diagrams reveal a chemical evolution from calcium-bicarbonate waters at high elevations to sodium-chloride waters in the lowlands, while scatter-plot analysis distinguishes local, intermediate, and regional flow systems. Elevated boron concentrations linked to borate deposits on Pichupichu volcano pose a potential health risk in supply springs such as La Bedoya. Isotopic signatures confirm that wells are recharged predominantly by high-altitude rainfall (>4000 m a.s.l.), whereas springs integrate water from multiple elevations through fractured volcanic formations. These findings provide a scientific basis for recharge-zone protection, abstraction planning, and water-quality monitoring to sustain groundwater supply under increasing urbanization and climatic variability. Full article

The spatial–temporal impact of the El Niño–Southern Oscillation (ENSO) phenomenon in Peru is characterised by marked regional variability, affecting the economy and general well-being. This study focuses on the Piura region, which is highly sensitive to ENSO events, with the aim of determining the implications for land management and climate adaptation in the Peruvian coastal region, particularly in the context of ENSO events. The objective of the study is to ascertain the correlation between sea surface temperature (SST) anomalies and the Normalised Difference Vegetation Index (NDVI) in the region. The researchers employed a machine learning approach to model and predict monthly NDVI behaviour, incorporating spatial and seasonal variables from the Moderate Resolution Imaging Spectroradiometer (MODIS) during two periods of ENSO occurrence on the Peruvian coast (2017; 2023) and the one-year post-occurrence periods (2018; 2024). The results demonstrated a correlation between NDVI and SST anomalies in coastal provinces such as Sechura and Morropón, indicating sensitivity to oceanic conditions. In contrast, high Andean provinces such as Ayabaca and Huancabamba exhibited more moderate values, indicating a weaker dependence on SST variability. The study also found that the NDVI exhibited a marked monthly variation associated with altitudinal gradients and climatic conditions. This research demonstrates the potential of remote sensing and GIS technologies in capturing climate-sensitive land-use dynamics and provides a framework for operational monitoring and decision support. Full article