Variation in Avian Predation Pressure as a Driver for the Diversification of Periodical Cicada Broods.

AbstractPeriodical cicadas live 13 or 17 years underground as nymphs, then emerge in synchrony as adults to reproduce. Developmentally synchronized populations called broods rarely coexist, with one dominant brood locally excluding those that emerge in off years. Twelve modern 17-year cicada broods are believed to have descended from only three ancestral broods following the last glaciation. The mechanisms by which these daughter broods overcame exclusion by the ancestral brood to synchronously emerge in a different year, however, are elusive. Here, we demonstrate that temporal variation in the population density of generalist predators can allow intermittent opportunities for new broods to invade, even though a single brood remains dominant most of the time. We show that this mechanism is consistent, in terms of the type and frequency of brood replacements, with the distribution of periodical cicada broods throughout North America today. Although we investigate one particularly charismatic case study, the mechanisms involved (competitive exclusion, Allee effects, trait variation, predation, and temporal variability) are ubiquitous and could contribute to patterns of species diversity in a range of systems.

Periodical Cicada Emergences Affect Masting Behavior of Oaks.

AbstractOaks (Quercus spp.) are masting species exhibiting highly variable and synchronized acorn production. We investigated the hypothesis that periodical cicadas (Magicada spp.), well known to have strong effects on the ecosystems in which they occur, affect acorn production of oaks through their xylem feeding habits as nymphs, the oviposition damage they inflict as adults during emergences, or the nutrient pulse resulting from the decomposition of their bodies following breeding. We found negative effects on acorn production during emergence years and the year following emergences and enhanced acorn production 2 years after emergence. We also found evidence indicating a significant effect of cicada emergences on spatial synchrony of acorn production by trees growing within the range of the same cicada brood compared with different broods. These results demonstrate that periodical cicadas act as a trophic environmental "veto" depressing acorn production during and immediately following emergences, after which the nutrient pulse associated with the cicada's demise enhances oak reproduction.

Histologic findings of Massospora cicadina infection in periodical cicadas (Magicicada septendecim).

Massospora cicadina, an obligate fungal pathogen in the subphylum Entomophthoromycotina (Zoopagomycota), infects periodical cicadas (Magicicada spp.) during their adult emergence and modifies their sexual behavior to maximize fungal spore dissemination. In this study, 7 periodical cicadas from the Brood X emergence in 2021 infected by M. cicadina were histologically examined. In 7 of 7 cicadas, fungal masses replaced the posterior portion of the abdominal cavity, effacing portions of the body wall, reproductive organs, alimentary tract, and fat bodies. No appreciable inflammation was noted at the intersections of the fungal masses and host tissues. Fungal organisms were present in multiple morphologies including protoplasts, hyphal bodies, conidiophores, and mature conidia. Conidia were clustered into eosinophilic membrane-bound packets. These findings help uncover the pathogenesis of M. cicadina by suggesting there is evasion of the host immune response and by providing a more in-depth description of its relationship with Magicicada septendecim than previously documented.

Do adult Magicicada (Hemiptera: Cicadidae) feed? Historical perspectives and evidence from molecular gut content analysis.

The periodical cicadas in the genus Magicicada are remarkable for their unusual life histories and dramatic synchronized emergences every 13 or 17 years. While aspects of their evolution, mating behaviors, and general biology have been well-characterized, there is surprising uncertainty surrounding the feeding habits of the short-lived adult stage. Despite a tentative scientific consensus to the contrary, the perception that adult Magicicada do not feed has persisted among the general public, and recent studies are lacking. We directly investigated the feeding behavior of Magicicada spp. through high-throughput sequencing (HTS)-based dietary analysis of nymphs, freshly molted (teneral) adults, and fully sclerotized adults collected from orchard and wooded habitats during the 2021 emergence of Brood X. Identifiable plant DNA (trnF, ITS amplicons) was successfully recovered from nymphs and adults. No plant DNA was recovered from teneral adults, suggesting that all DNA recovered from sclerotized adults was ingested during the post-teneral adult stage. Both nymphs and adults were found to have ingested a range of woody and herbaceous plants across 17 genera and 14 families. Significantly more plant genera per individual were recovered from adults than from nymphs, likely reflecting the greater mobility of the adult stage. We hypothesize that the demonstrated ingestion of plant sap by Magicicada adults is driven by a need to replace lost water and support specialized bacteriome-dwelling endosymbionts that cicadas depend upon for growth and development, which constitutes true feeding behavior.

Using a hybrid approach to apportion potential source locations contributing to excess cancer risk of PM2.5-bound PAHs during heating and non-heating periods in a megacity in the Middle East.

Polycyclic aromatic hydrocarbons (PAHs) represent one of the major toxic pollutants associated with PM2.5 with significant human health and climate effects. Because of local and long-range transport of atmospheric PAHs to receptor sites, higher global attentions have been focused to improve PAHs pollution emission management. In this study, PM2.5 samples were collected at three urban sites located in the capital of Iran, Tehran, during the heating and non-heating periods (H-period and NH-period). The US EPA 16 priority PAHs were analyzed and the data were processed to the following detailed aims: (i) investigate the H-period and NH-period variations of PM2.5 and PM2.5-bound PAHs concentrations; (ii) identify the PAHs sources and the source locations during the two periods; (iii) carry out a source-specific excess cancer risk (ECR) assessment highlighting the potential source locations contributing to the ECR using a hybrid approach. Total PAHs (TPAHs) showed significantly higher concentrations (1.56-1.89 times) during the H-period. Among the identified PAHs compounds, statistically significant periodical differences (p-value < 0.05) were observed only between eight PAHs species (Nap, BaA, Chr, BbF, BkF, BaP, IcdP, and DahA) at all three sampling sites which can be due to the significant differences of PAHs emission sources during H and NH-periods. High molecular weight (HMW) PAHs accounted for 52.7% and 46.8% on average of TPAHs during the H-period and NH-period, respectively. Positive matrix factorization (PMF) led to identifying four main PAHs sources including industrial emissions, petrogenic emissions, biomass burning and natural gas emissions, and vehicle exhaust emissions. Industrial and petrogenic emissions exhibited the highest contribution (19.8%, 27.2%, respectively) during the NH-period, while vehicle exhaust and biomass burning-natural gas emissions showed the largest contribution (40.7%, 29.6%, respectively) during the H-period. Concentration weighted trajectory (CWT) on factor contributions was used for tracking the potential locations of the identified sources. In addition to local sources, long-range transport contributed to a significant fraction of TPHAs in Tehran both during the H- and NH-periods. Source-specific carcinogenic risks assessment apportioned vehicle exhaust (44.2%, 2.52 × 10-4) and biomass burning-natural gas emissions (33.9%, 8.31 × 10-5) as the main cancer risk contributors during the H-period and NH-period, respectively. CWT maps pointed out the different distribution patterns associated with the cancer risk from the identified sources. This will allow better risk management through the identification of priority PAHs sources.

Evaluation of Solid Particle Number Sensors for Periodic Technical Inspection of Passenger Cars.

Following the increase in stringency of the European regulation limits for laboratory and real world automotive emissions, one of the main transport related aspects to improve the air quality is the mass scale in-use vehicle testing. Solid particle number (SPN) emissions have been drastically reduced with the use of diesel and gasoline particulate filters which, however, may get damaged or even been tampered. The feasibility of on-board monitoring and remote sensing as well as of the current periodical technical inspection (PTI) for detecting malfunctioning or tampered particulate filters is under discussion. A promising methodology for detecting high emitters is SPN testing at low idling during PTI. Several European countries plan to introduce this method for diesel vehicles and the European Commission (EC) will provide some guidelines. For this scope an experimental campaign was organized by the Joint Research Centre (JRC) of the EC with the participation of different instrument manufacturers. Idle SPN concentrations of vehicles without or with a malfunctioning particulate filter were measured. The presence of particles under the current cut-off size of 23 nm as well as of volatile particles during idling are presented. Moreover, the extreme case of a well performing vehicle tested after a filter regeneration is studied. In most of the cases the different sensors used were in good agreement, the high sub-23 nm particles existence being the most challenging case due to the differences in the sensors' efficiency below the cut-off size.

Open Access Physical Therapy Journals: Do Predatory Journals Publish Lower-Quality Randomized Controlled Trials?

OBJECTIVES: To compare the quality of randomized controlled trials (RCTs) published in predatory and nonpredatory journals in the field of physical therapy. DATA SOURCES: From a list of 18 journals included either on Beall's list (n=9) or in the Directory of Open Access Journals (DOAJ) (n=9), 2 independent assessors extracted all the RCTs published between 2014 and 2017. When journals published more than 40 RCTs, a sample of 40 trials was randomly extracted, preserving the proportions among years. Indexing in PubMed, country of journal publication, and dates of submission or acceptance were also recorded for each journal. MAIN OUTCOME MEASURES: The PEDro (Physiotherapy Evidence Database) scale and duration of the peer review. RESULTS: Four hundred ten RCTs were included. The mean PEDro score of articles published in non-Beall, DOAJ journals was higher than those published in Beall journals (mean score ± SD, 5.8±1.7 vs 4.5±1.5; P<.001), with the differences increasing when the indexing in PubMed was also considered (6.5±1.5 vs 4.4±1.5; P<.001). The peer review duration was significantly longer in non-Beall than in Beall journals (mean duration [d] ± SD, 145.2±92.9 vs 45.4±38.8; P<.001) and in journals indexed in PubMed than in nonindexed journals (136.6±100.7 vs 60.4±55.7; P<.001). Indexing in PubMed was the strongest independent variable associated with the PEDro score (adjusted R2=0.182), but noninclusion on Beall's list explained an additional, albeit small, portion of the PEDro score variance (cumulative adjusted R2=0.214). CONCLUSIONS: Potentially predatory journals publish lower-quality trials and have a shorter peer review process than non-Beall journals included in the DOAJ database.

Bifurcations of cycles in nonlinear semelparous Leslie matrix models.

This paper develops a method for studying bifurcations that occur in a neighborhood of the extinction equilibrium in nonlinear semelparous Leslie matrix models. The method uses a Lotka-Volterra equation with cyclic symmetry to detect the existence and to evaluate the stability of bifurcating equilibria and cycles. An application of the method provides sharp stability conditions for both a single-class cycle and a positive equilibrium bifurcating from the extinction equilibrium. The stability condition for a bifurcating single-class cycle confirms that the periodicity observed in periodical insects occurs if competition is more severe between than within age-classes. The developed method is also used to investigate two examples of nonlinear semelparous Leslie matrix models incorporating predator satiation. The investigation shows that a single-class cycle, which is associated with the periodicity in periodical insects, is a unique stable cycle in a neighborhood of the extinction equilibrium if the density effects in survival probabilities are identical among age-classes.

Monitoring of high-yield and periodical processes in health care.

Statistical control charts have found valuable applications in health care, having been largely adopted from operations research in manufacturing. However, the most common types are not best-suited to monitor high-yield processes (outcomes comprising true/false fractions, 'near-zero') and periodical processes (characterized by sequences of single populations of finite sizes), but rather to monitor variable vital signs levels and, to a lesser degree, service performance indicators. We discuss control charts that are most suitable for fraction non-conforming measurements. We focus particularly on high-yield and periodical processes, i.e. range in which out-of-control conditions are expected and should be identified. For these conditions, we discuss control charts based on the family of hypergeometric distributions, explaining and comparing their application to more traditional alternatives with two health care case studies. We demonstrate that hypergeometric-type control charts provide higher sensitivity in timely identification of changing rare event fractions and are well-suited for monitoring of periodical processes, while remaining more resistant to false alarms, versus their alternatives.

The Risk of Developing Multiple Primary Cancers among Long-Term Survivors Five Years or More after Stomach Carcinoma Resection.

Recently, the number of long-term survivors of ≥ 5 years after stomach carcinoma resection is increasing in Japan. The clinical courses of 4,883 patients who underwent stomach carcinoma resection were retrospectively reviewed to investigate the cause of death including multiple primary cancers (MPC) and delayed stomach carcinoma recurrence among long-term survivors of ≥ 5 years. Of 3,061 patients who survived for ≥ 5 years, 1,203 patients (39.3%) were dead after 5 years survival, including 299 patients (24.9%) who died of MPC. Of 84 patients (7.0%) who died of recurrent stomach carcinoma, 25 patients were newly diagnosed ≥ 5 years postoperative. The most common site of MPC was lung in 124 patients, and 347 patients (44.7%) had a smoking-related MPC, including 124 lung, 63 esophagus, 62 head and neck, and 98 other cancers. We examined the prognostic differences in 527 patients with MPC according to the diagnosis time. In 325 patients of long-term survivors in whom MPC was diagnosed ≥ 5 years postoperative, 5-year survival rate and the median survival time after diagnosis were 35.1% and 17.7 months, respectively. This outcome was significantly poorer than that of 160 patients in whom MPC was diagnosed within 5 years postoperative (58.5% and 62.7 months, P < 0.0001). In conclusion, MPC accounted for approximately a quarter of the cause of death in long-term survivors. Lifestyle instructions including smoking cessation are important. Periodical cancer screening allows the early asymptomatic diagnosis and may contribute to a decrease in cancer mortality of MPC in long-term cancer survivors.

Improved Design via Simulation of Micro-Modified PVDF and its Copolymer Energy Harvester with High Electrical Outputs.

In this work, micro-modified polyvinylidene fluoride (PVDF) and its copolymer poly(vinylidene-trifluoroethylene) (P(VDF-TrFE)) with salient enhancement in current output are demonstrated. The influence of surface-modified structure characteristics on electrical properties of energy harvester is systematically analyzed based on the finite element method. For vertical load mode, eight structures consisting of banded and disjunctive groups are compared to evaluate the voltage performance. The cylinder is proved to be the best structure of 3.25 V, compared to the pristine structure of 0.99 V (P(VDF-TrFE)). The relevant experiment has been done to verify the simulation. The relationship between radius, height, force and distance to the voltage output of the cylinder allocation is discussed. For periodical changing load mode, the cylinder modified structure shows a conspicuous enhancement in current output. The suitable resistance, current-voltage and frequency, the relationship between loading speed and current, and the ductility of current loading are studied. For 30 kHz, the peak current is 20 times larger than the flat plate structure. Tip shape mode and fusiform shape mode are found, which show the different shapes of the peak current-frequency curves. Four electrical loading circuit properties are also discussed: the suitable resistance of the system, synchronism of current and voltage, time delay nature of energy harvester and current-loading relationship. The simulation results can provide some theoretical basis for designing the energy harvester and piezoelectric nanogenerator (PENG).

Comparisons of Laboratory and On-Road Type-Approval Cycles with Idling Emissions. Implications for Periodical Technical Inspection (PTI) Sensors.

For the type approval of compression ignition (diesel) and gasoline direct injection vehicles, a particle number (PN) limit of 6 × 1011 p/km is applicable. Diesel vehicles in circulation need to pass a periodical technical inspection (PTI) test, typically every two years, after the first four years of circulation. However, often the applicable smoke tests or on-board diagnostic (OBD) fault checks cannot identify malfunctions of the diesel particulate filters (DPFs). There are also serious concerns that a few high emitters are responsible for the majority of the emissions. For these reasons, a new PTI procedure at idle run with PN systems is under investigation. The correlations between type approval cycles and idle emissions are limited, especially for positive (spark) ignition vehicles. In this study the type approval PN emissions of 32 compression ignition and 56 spark ignition vehicles were compared to their idle PN concentrations from laboratory and on-road tests. The results confirmed that the idle test is applicable for diesel vehicles. The scatter for the spark ignition vehicles was much larger. Nevertheless, the proposed limit for diesel vehicles was also shown to be applicable for these vehicles. The technical specifications of the PTI sensors based on these findings were also discussed.

A Hybrid Model for the Population Dynamics of Periodical Cicadas.

In addition to their unusually long life cycle, periodical cicadas, Magicicada spp., provide an exceptional example of spatially synchronized life stage phenology in nature. Within regions ("broods") spanning 50,000-500,000 km[Formula: see text], adults emerge synchronously every 13 or 17 years. While satiation of avian predators is believed to be a key component of the ability of these populations to reach high densities, it is not clear why populations at a single location remain entirely synchronized. We develop nonlinear Leslie matrix-type models of periodical cicadas that include predation-driven Allee effects and competition in addition to reproduction and survival. Using both analytical and numerical techniques, we demonstrate the observed presence of a single brood critically depends on the relationship between fecundity, competition and predation. We analyze the single-brood, two-brood and all-brood equilibria in the large life span limit using a tractable hybrid approximation to the Leslie matrix model with continuous time competition in between discrete reproduction events. Within the hybrid model, we prove that the single-brood equilibrium is the only stable equilibrium. This hybrid model allows us to quantitatively predict population sizes and the range of parameters for which the stable single-brood and unstable two-brood and all-brood equilibria exist. The hybrid model yields a good approximation to the numerical results for the Leslie matrix model for the biologically relevant case of a 17-year life span.

At 100 years of Gaceta Médica de México resumption.

Gaceta Médica de México, official journal of the National Academy of Medicine of Mexico, began its circulation on September 15, 1864, and continues to be positioned as the oldest medical periodical publication. However, its publication was temporarily interrupted. The present study analyzes the interruption suffered by Gaceta in 1916, its resumption in 1919, and the causes that originated that discontinuity. The consequences of the so-called Mexican revolution and the enthusiasm and commitment of the academy and its editors to continue working for the progress of national medicine are discussed.

A 100 años de la reanudación de Gaceta Médica de México.

Gaceta Médica de México, official journal of the National Academy of Medicine of Mexico, began its circulation on September 15, 1864, and continues to be positioned as the oldest medical periodical publication. However, its publication was temporarily interrupted. The present study analyzes the interruption suffered by Gaceta in 1916, its resumption in 1919, and the causes that originated that discontinuity. The consequences of the so-called Mexican revolution and the enthusiasm and commitment of the academy and its editors to continue working for the progress of national medicine are discussed.

Gaceta Médica de México, órgano oficial de la Academia Nacional de Medicina de México, empezó su tiraje el 15 de septiembre de 1864 y continúa posicionada como la publicación periódica médica de mayor antigüedad. Sin embargo, en algún momento de su historia la publicación fue suspendida temporalmente. El presente estudio analiza la interrupción que sufrió Gaceta en 1916, su reanudación en 1919 y las causas que originaron esa discontinuidad. Se habla de las consecuencias que dejó la denominada Revolución Mexicana y del entusiasmo y compromiso de la Academia y sus editores por seguir trabajando por el progreso de la medicina nacional.

Design of Controllable Novel Piezoelectric Components for Microfluidic Applications.

This paper reviews recent investigations and achievements in the design of controllable functional components for improving microfluidic systems, its effectiveness, and functionality. The main purpose was to design novel microstructures with piezoelectric properties (microresonators), which enable one to control the effectiveness of fluid flow in micro-hydro-mechanical devices for biomedical/biochemical purposes. Controllable properties were obtained by incorporating different types of binders in a piezoelectric ceramic matrix (lead zirconate titanate): polyvinyl butyral (PVB), poly methyl methacrylate (PMMA), and polystyrene (PS). The change in chemical composition of PZT helps to manipulate the piezoelectric characteristics, surface morphology, mechanical properties, etc., of the designed microfluidic element with the microstructure in it.

The right of a doctor to inform an employer of contraindications to perform a certain type of work by an employee / Prawo lekarza do informowania pracodawcy o przeciwwskazaniach do wykonywania okreslonego rodzaju pracy przez pracownika

BACKGROUND: The aim of this study is to analyze the legal regulations that pertain to the duty of doctor-patient privilege and the possibility of its repeal on the plane to provide information about the patient's health status to his employer. MATERIAL AND METHODS: The material constitutes the current Polish law regulations relating to the medical duty of doctor­patient privilege as well as provisions defining the scope of information on the patient's health status that may be transferred to a patient's employer. RESULTS: The doctor has no right to provide the employer with information on contraindications to perform a specific job, if the information was obtained in the mode of providing health services that are not eligible for the catalogue of preliminary/preventive/control examinations. The basis for the doctor providing information to the employer cannot be an exception to the obligation of medical confidentiality, which is governed by art. 40 § 2 pts 1­6 of the Act of Medical Profession, under which cases of admission of professional secrecy were listed, which makes it impossible to use the cited article in cases other than strictly specified in its content. CONCLUSIONS: Polish law specifies the circumstances in which it is possible to provide an employer with the medical information on the patient's health. However, there are regulations that provide for the information on contraindications to perform a certain type of work or job to be transmitted if the information has been obtained in a manner other than as provided in the ordinance on medical examinations of employees. Med Pr 2018;69(6):613­620

Medición de la obsolescencia de la información en revistas de salud pública de México.

INTRODUCCIÓN: En el proceso de comunicación científica, la obsolescencia se define como el descenso de la validez o utilidad de la información en el tiempo. OBJETIVO: Determinar el grado de obsolescencia de la información publicada en tres revistas de salud pública en México y cuantificar su pérdida de utilidad anual en un lapso determinado. MÉTODO: Estudio bibliométrico multisincrónico de revistas indizadas, arbitradas y activas, con más de 30 años de antigüedad. Variables analizadas: año de publicación de los artículos fuente, año de las referencias, edad de estas últimas. De las referencias de los artículos originales publicados entre 2008 y 2013 se obtuvieron variables e indicadores conforme el modelo matemático de Brooks y el método de la vida media. RESULTADOS: Se obtuvieron medidas de obsolescencia y valores medios de las variables para cada revista. Los valores indicaron vida media de 7.5 años; promedio de actualidad de 39.76 %, factor de envejecimiento de 91.15 %, pérdida de utilidad de 8.85 % anual, lo que representa la obsolescencia de la literatura en este tema y el país. CONCLUSIÓN: Este estudio delinea un perfil de obsolescencia para cada revista: el factor de envejecimiento y la pérdida anual de utilidad son consistentes con los mostrados por las principales revistas de salud pública en América Latina y España. INTRODUCTION: In the process of scientific communication, obsolescence is defined as the decrease of information validity or usefulness over time. OBJECTIVE: To determine the degree of obsolescence of information published in three public health journals in Mexico and quantify their annual utility loss in a given period. METHOD: Multisynchronous bibliometric study of indexed, peer-reviewed and active journals, with more than 30 years of existence. Analyzed variables: source articles' year of publication, references' year, age of the latter. From the references of original articles published between 2008 and 2013, variables and indicators were obtained according to Brooks' mathematical model and the half-life method. RESULTS: Obsolescence measurements and variables' mean values were obtained for each journal. The values obtained indicate a half-life of 7.5 years; actuality average, 39.76%; aging factor, 91.15%; loss of usefulness, 8.85% per year, which represents obsolescence of literature on this subject and country. CONCLUSIONS: This study delineates an obsolescence profile for each journal: the aging factor and annual loss of usefulness are consistent with those shown by the leading public health journals in Latin America and Spain.

Screening and periodical medical examinations as important part of public health: problem of the legal implementation.

OBJECTIVE: Introduction: Public health is an important concept, which is continually being globalized and integrated into today's society. It helps to improve and prolong the quality of life of people and prevent the spread of epidemics and serious incurable diseases. The components of public health include protection, prevention, and promotion. Prevention, the measures taken to prevent disease as opposed to treatment consist of screening and periodical medical examinations. There are two types of screening- universal screening and case finding (individual screening). Universal screening and periodical medical examination are identical concepts; the terms dispensary and individual screening (case finding) have similar meanings and can be used interchangeably. These concepts and their importance are analyzed in this research. The aim: A research on the legal regulation of periodic health examinations and screening as a two systems, which provides the implementation of prevention within the public health. Analysis of foreign experience such countries as: Great Britain, USA, Austria, Germany, Australia, France, Italy and others. PATIENTS AND METHODS: Materials and methods: The research based on: Ukrainian legislation, European Union's Law Acts, decisions of the ECHR, EU's member-states law, WHO Acts and Recommendations, scientific articles. The research is also based on general scientific and special research methods (such as dialectical, comparative, analytic, synthetic). RESULTS: Review: In Europe (except Germany and Austria) is happening the transition from the system of mandatory periodical medical examination to new screening system. However, despite this, periodical medical examinations of Europeans held in connection with exist system health insurance (both voluntary and mandatory). CONCLUSION: Conclusions: Screening and periodical medical examinations are two of the most important aspects of public health as they help to diagnose diseases at an early stage, even before showing any symptoms. Screening and periodical medical examinations ensures the safety and health of the entire population as opposed to certain individuals and therefore be mandatory procedure in today's society.

Investigation of Two Kinds of Periodical Surface Structures Induced by Femtosecond Laser on the Surface of Titanium Plate.

Two kinds of laser-induced periodical structures observed on metal titanium plate irradiated by femtosecond laser (fs-laser) are reported, including the fs-laser-induced concentric rings and periodical subwavelength ripples. The rings can be produced only when the titanium target is located before the focal plane. The period and distribution of the rings stay almost fixable with the change of laser fluence and pulse number. The average cross section area (ACSA) is introduced to investigate the material removal behavior with the growth of the rings. The rings grow with the accumulation of laser pulses and the increase of the laser fluence, but the growth rate will be moderated with the increase of the pulse number. The ripples are obtained in an annular region when powerful multi-pulses irradiate on the target surface. The ripple period varies with laser fluence and location. And the annular region migrates outward when the laser fluence increases. We suggest that the formations of ripples are attributed to the propagation of the laser-stimulated surface plasma wave (SPW) on the air/ti interface. The dependence of the ripple period on the pulse fluence calculated by the SPW model agrees well with our experimental observation. The investigation improves the understanding of the two kinds of periodical surface structures both in their appearances and mechanisms.