rSEM: System-Entropy-Measure-Guided Routing Algorithm for Industrial Wireless Sensor Networks.

In this paper, a new system entropy measure is used to optimize the routing algorithm in power consumption. We introduce the system entropy measure into the problem of industrial wireless sensor networks (iWSNs) routing and propose a high-performance routing algorithm guided by the system entropy measure (rSEM). Based on the cluster iWSNs architecture, the rSEM selects the cluster heads and cluster member nodes successively, according to the system entropy measure, and constructs the iWSNs with the minimum system entropy. The method of the cluster head selection is traversal, while the method of the cluster member selection is a greedy algorithm to reduce the complexity. The experiments show that the power consumption of the iWSNs generated by the rSEM is in the same order of magnitude as that of Dijkstra in both 2D and 3D scenarios. In addition, the delay of the rSEM is slightly higher than that of LEACH. Therefore, the rSEM is suitable for networks that are sensitive to both the delay and power consumption. The rSEM puts forward a new idea for the design of routing for the next-generation iWSNs, which improves the overall network performance according to the network topology, instead of relying on the power consumption or delay performance only.

Methodology development for calibration assessment using quasi-deep convective clouds with application to Aqua MODIS TEB.

Deep convective clouds (DCC) are identified by using a combination of brightness temperature (BT) and visible reflectance thresholds. Moreover, it is common practice to use daytime DCC measurements for the calibration assessment of reflective solar and longwave infrared (LWIR) bands. The DCC cold core is suitable for the MODIS Thermal Emissive Bands (TEB) calibration assessment; more specifically, for the offset effect in the quadratic calibration function. However, the reflected solar radiance in the daytime DCC measurements affects the midwave infrared (MWIR) bands. Thus, an assessment over low BT measurements is not applicable to these bands. Because of this, a quasi-DCC (qDCC) technique is developed for the MWIR bands calibration assessment. The feasibility of using nighttime DCC measurements is demonstrated by comparing the DCC and daytime qDCC techniques. A DCC normalization method is also developed to remove the DCC fluctuation impact and enhance the assessment accuracy. The DCC measurements' distribution is asymmetrical for all TEB, and their BT ranges fluctuate around 20 K. An empirical model is developed and applied to normalize the measurements over DCC to a reference temperature. After the normalization, the DCC and qDCC measurements' distributions are close to symmetrical and Gaussian in shape. These improvements are applied to the Aqua MODIS instrument. The calibration stability, noise performance, and consistency are evaluated for all Aqua MODIS TEB. Lastly, the Aqua MODIS formatter reset effect on the calibration offset bias between two mirror sides is analyzed, and a calibration coefficient correction is proposed for future calibration improvements.

Determination of the NOAA-20 VIIRS screen transmittance functions with both the yaw maneuver and regular on-orbit calibration data.

The Visible Infrared Imaging Radiometer Suite (VIIRS) aboard the NOAA-20 satellite regularly performs on-orbit radiometric calibration of its reflective solar bands (RSBs) through observations of an onboard sunlit solar diffuser (SD). The incident sunlight passes through an attenuation screen (the SD screen) and then scatters off the SD to provide a radiance source for the calibration. The on-orbit change of the SD's bidirectional reflectance distribution function (BRDF), referred to as the H-factor, is determined by an onboard solar diffuser stability monitor (SDSM) whose eight detectors alternately observe the Sun through another attenuation screen (the SDSM screen) and the sunlit SD. The products of the SD screen transmittance and the BRDF at the mission start for both the SDSM and RSBs and the SDSM screen effective transmittance were measured prelaunch. Large unrealistic undulations in the retrieved H-factor were seen when using the prelaunch screen functions. To improve the accuracy of the retrieved H-factor, shortly after the satellite launch, 15 yaw maneuvers were performed to further characterize the screens. Although significantly improved, the H-factor derived using the screen functions determined from the yaw maneuver data still has large unrealistic undulations, revealing that the solar azimuth angular step size of the yaw maneuvers is too large. In this paper, we add high-quality regular on-orbit SD calibration data to the yaw maneuver data to further improve the relative product of the SD screen effective transmittance and the BRDF at the mission start for the SDSM and the SDSM screen relative effective transmittance. The H-factor time series derived from the newly determined screen transmittance functions is much smoother than that derived from using only the yaw maneuver data and thus considerably improves the radiometric calibration accuracy.

NOAA-20 VIIRS polarization effect and its correction.

The follow-on Visible Infrared Imaging Radiometer Suite (VIIRS) housed in the NOAA-20 satellite was launched on 18 November 2017. It has 22 spectral bands, among which 14 are reflective solar bands (RSBs) covering the wavelength range from 411 to 2258 nm. Prelaunch polarization sensitivity measurements have revealed that NOAA-20 VIIRS RSBs are much more sensitive to polarization of the incident light than its predecessor, the VIIRS on the Suomi National Polar-orbiting Partnership. For the short wavelength bands, i.e., M1-M4, the polarization sensitivities are out of specifications, especially for band M1, for which the polarization factors can be as large as ∼6%. The polarization effect induces striping in imagery along the track and radiometric bias both along the scan and along the track, resulting in much larger uncertainties in the environmental data records (EDR). In this paper, the polarization effect correction algorithms are described and applied to the NOAA-20 VIIRS RSBs for ocean scenes where the top-of-atmosphere radiance can be separated into the ocean normalized water-leaving radiance, the basis of the ocean color EDR, and the sunlight reflected by the atmosphere, which can be mostly described by the Rayleigh scattering radiance. The errors of the sensor data records (SDR or Level-1B radiance) due to the polarization effect can be as large as ∼1% for bands M1 and M2, and those in the ocean normalized water-leaving radiances are about 13% and 10% for wavelengths at 411 nm (band M1) and 445 nm (band M2), respectively. The polarization effect also induces strong striping in both NOAA-20 VIIRS RSB SDR and normalized water-leaving radiances. It is demonstrated that with the polarization correction applied, the aforementioned errors and artifacts are successfully removed.

GOES-16/ABI Thermal Emissive Bands Assessments using GEO-LEO-GEO Double Difference.

Geostationary satellite (GOES)-16/ABI and Himawari-8/AHI represent a significant improvement over the imagers on board previous GOES. Their bands 7-16 are infrared channels covering the 3.9 to 13.3 µm spectral range and with a sub-point spatial resolution of 2 km. Their spectral coverage of the thermal emissive bands (TEB) are almost identical and both instruments employ similar calibration strategies using an on-board blackbody (BB) and a space look. The inter-comparison between the two instruments will be very helpful for their calibration assessments and their product quality enhancements. GOES-16 was launched on November 19, 2016, initially to a test position at 89.5° West and reached its operational position (longitude of 75.2° West) on December 11, 2017. The Himawari-8 spacecraft was launched on October 7, 2014 and the observation focuses on Asia-Pacific region. In this work, an inter-comparison of their TEB measurement is performed using double difference with Aqua MODIS. The same type of scenes are selected for the two instruments and their measurements with the closest observation times are compared with Aqua MODIS matching bands. The view angle effect is corrected and their spectral mismatching effect is estimated. The dependence on the scene uniformity is analyzed. The ABI-AHI differences are within 0.3K for bands 10 (7.35 µm), 11 (8.44 µm), 12 (9.64 µm), and 14 (11.24 µm), and up to 0.8K difference for bands 15 (12.38 µm) and 16 (13.28 µm). The ABI precision is better than AHI for all TEB and their image navigation and registration (INR) precisions are comparable. In general, the ABI performance before and after re-location is consistent.

Suomi NPP VIIRS solar diffuser screen transmittance model and its applications.

The visible infrared imaging radiometer suite on the Suomi National Polar-orbiting Partnership satellite calibrates its reflective solar bands through observations of a sunlit solar diffuser (SD) panel. Sunlight passes through a perforated plate, referred to as the SD screen, before reaching the SD. It is critical to know whether the SD screen transmittance measured prelaunch is accurate. Several factors such as misalignments of the SD panel and the measurement apparatus could lead to errors in the measured transmittance and thus adversely impact on-orbit calibration quality through the SD. We develop a mathematical model to describe the transmittance as a function of the angles that incident light makes with the SD screen, and apply the model to fit the prelaunch measured transmittance. The results reveal that the model does not reproduce the measured transmittance unless the size of the apertures in the SD screen is quite different from the design value. We attribute the difference to the orientation alignment errors for the SD panel and the measurement apparatus. We model the alignment errors and apply our transmittance model to fit the prelaunch transmittance to retrieve the "true" transmittance. To use this model correctly, we also examine the finite source size effect on the transmittance. Furthermore, we compare the product of the retrieved "true" transmittance and the prelaunch SD bidirectional reflectance distribution function (BRDF) value to the value derived from on-orbit data to determine whether the prelaunch SD BRDF value is relatively accurate. The model is significant in that it can evaluate whether the SD screen transmittance measured prelaunch is accurate and help retrieve the true transmittance from the transmittance with measurement errors, consequently resulting in a more accurate sensor data product by the same amount.

Aqua and Terra MODIS RSB calibration comparison using BRDF modeled reflectance.

The inter-comparison of MODIS reflective solar bands onboard Aqua and Terra is very important for assessment of each instrument's calibration. One of the limitations is the lack of simultaneous nadir overpasses. Their measurements over a selected Earth view target have significant differences in solar and view angles, which magnify the effects of atmospheric scattering and Bidirectional Reflectance Distribution Function (BRDF). In this work, an inter-comparison technique is formulated after correction for site's BRDF and atmospheric effects. The reflectance measurements over Libya desert sites 1, 2, and 4 from both the Aqua and Terra MODIS are regressed to a BRDF model with an adjustable coefficient accounting for calibration difference. The ratio between Aqua and Terra reflectance measurements are derived for bands 1 to 9 and the results from different sites show good agreement. For year 2003, the ratios are in the range of 0.985 to 1.010 for band 1 to 9. Band 3 shows the lowest ratio 0.985 and band 1shows the highest ratio 1.010. For the year 2014, the ratio ranges from approximately 0.983 for bands 2 and 1.012 for band 8. The BRDF corrected reflectance for the two instruments are also derived for every year from 2003 to 2014 for stability assessment. Bands 1 and 2 show greater than 1% differences between the two instruments. Aqua bands 1 and 2 show downward trends while Terra bands 1 and 2 show upward trends. Bands 8 and 9 of both Aqua and Terra show large variations of reflectance measurement over time.

Band-to-Band Misregistration of the Images of MODIS On-Board Calibrators and Its Impact to Calibration.

The MODIS instruments aboard Terra and Aqua satellites are radiometrically calibrated on-orbit with a set of on-board calibrators (OBC) including a solar diffuser (SD), a blackbody (BB) and a space view (SV) port through which the detectors can view the dark space. As a whisk-broom scanning spectroradiometer, thirty-six MODIS spectral bands are assembled in the along-scan direction on four focal plane assemblies (FPA). These bands capture images of the same target sequentially with the motion of a scan mirror. Then the images are co-registered on board by delaying appropriate band-dependent amount of time depending on the band locations on the FPA. While this co-registration mechanism is functioning well for the "far field" remote targets such as Earth view (EV) scenes or the Moon, noticeable band-to-band misregistration in the along-scan direction has been observed for "near field" targets, in particular the OBCs. In this paper, the misregistration phenomenon is presented and analyzed. It is concluded that the root cause of the misregistration is that the rotating element of the instrument, the scan mirror, is displaced from the focus of the telescope primary mirror. The amount of the misregistration is proportional to the band location on the FPA and is inversely proportional to the distance between the target and the scan mirror. The impact of this misregistration to the calibration of MODIS bands is discussed. In particular, the calculation of the detector gain coefficient m1 of bands 8-16 (412 nm - 870 nm) is improved by up to 1.5% for Aqua MODIS.

Monochromatic measurements of the JPSS-1 VIIRS polarization sensitivity.

Polarization sensitivity is a critical property that must be characterized for spaceborne remote sensing instruments designed to measure reflected solar radiation. Broadband testing of the first Joint Polar-orbiting Satellite System (JPSS-1) Visible Infrared Imaging Radiometer Suite (VIIRS) showed unexpectedly large polarization sensitivities for the bluest bands on VIIRS (centered between 400 and 600 nm). Subsequent ray trace modeling indicated that large diattenuation on the edges of the bandpass for these spectral bands was the driver behind these large sensitivities. Additional testing using the National Institute of Standards and Technology's Traveling Spectral Irradiance and Radiance Responsivity Calibrations Using Uniform Sources was added to the test program to verify and enhance the model. The testing was limited in scope to two spectral bands at two scan angles; nonetheless, this additional testing provided valuable insight into the polarization sensitivity. Analysis has shown that the derived diattenuation agreed with the broadband measurements to within an absolute difference of about 0.4% and that the ray trace model reproduced the general features of the measured data. Additionally, by deriving the spectral responsivity, the linear diattenuation is shown to be explicitly dependent on the changes in bandwidth with polarization state.

Suomi National Polar-Orbiting Partnership Visible Infrared Imaging Radiometer Suite polarization sensitivity analysis.

The Visible Infrared Imaging Radiometer Suite (VIIRS) is one of five instruments onboard the Suomi National Polar-Orbiting Partnership (SNPP) satellite that launched from Vandenberg Air Force Base, California, on October 28, 2011. It is a whiskbroom radiometer that provides ±56.28° scans of the Earth view. It has 22 bands, among which 14 are reflective solar bands (RSBs). The RSBs cover a wavelength range from 410 to 2250 nm. The RSBs of a remote sensor are usually sensitive to the polarization of incident light. For VIIRS, it is specified that the polarization factor should be smaller than 3% for 410 and 862 nm bands and 2.5% for other RSBs for the scan angle within ±45°. Several polarization sensitivity tests were performed prelaunch for SNPP VIIRS. The first few tests either had large uncertainty or were less reliable, while the last one was believed to provide the more accurate information about the polarization property of the instrument. In this paper, the measured data in the last polarization sensitivity test are analyzed, and the polarization factors and phase angles are derived from the measurements for all the RSBs. The derived polarization factors and phase angles are band, detector, and scan angle dependent. For near-infrared bands, they also depend on the half-angle mirror side. Nevertheless, the derived polarization factors are all within the specification, although the strong detector dependence of the polarization parameters was not expected. Compared to the Moderate Resolution Imaging Spectroradiometer on both Aqua and Terra satellites, the polarization effect on VIIRS RSB is much smaller.

Noise Characterization and Performance of MODIS Thermal Emissive Bands.

The MODerate-resolution Imaging Spectroradiometer (MODIS) is a premier Earth observing sensor of the early 21st Century, flying on-board the Terra (T) and Aqua (A) spacecrafts. Both instruments far exceeded their 6 year design life and continue to operate satisfactorily for more than 15 and 13 years, respectively. The MODIS instrument is designed to make observations at nearly a 100% duty cycle covering the entire Earth in less than 2 days. The MODIS sensor characteristics include a spectral coverage from 0.41 µm - 14.4 µm, of which those wavelengths ranging from 3.7 µm - 14. 4 µm cover the thermal infrared region which is interspaced in 16 Thermal Emissive Bands (TEB). Each of the TEB contains 10 detectors which record samples at a spatial resolution of 1 km. In order to ensure a high level of accuracy for the TEB measured Top Of Atmosphere (TOA) radiances, an onboard BlackBody (BB) is used as the calibration source. This paper reports the noise characterization and performance of the TEB on various counts. First, the stability of the onboard BB is evaluated to understand the effectiveness of the calibration source. Next, key noise metrics such as the Noise Equivalent Temperature difference (NEdT) and the Noise Equivalent dn difference (NEdN) for the various TEB are determined from multiple temperature sources. These sources include the nominally controlled BB temperature of 290 K for T-MODIS and 285 K for A-MODIS, as well as a BB Warm Up - Cool Down (WUCD) cycle that is performed over a temperature range from roughly 270 K - 315 K. The Space View (SV) port that measures the background signal serves as a viable cold temperature source for measuring noise. In addition, a well characterized Earth View (EV) Target, the Dome C site located in the Antarctic plateau, is used for characterizing the stability of the sensor, indirectly providing a measure of the NEdN. Based on this rigorous characterization, a list of the noisy and inoperable detectors for the TEB for both instruments is reported to provide the science user communities quality control of the MODIS Level 1B calibrated product.

Assessment of S-NPP VIIRS On-orbit Radiometric Calibration and Performance.

The VIIRS instrument on board the S-NPP spacecraft has successfully operated for more than four years since its launch in October, 2011. Many VIIRS environmental data records (EDR) have been continuously generated from its sensor data records (SDR) with improved quality, enabling a wide range of applications in support of users in both the operational and research communities. This paper provides a brief review of sensor on-orbit calibration methodologies for both the reflective solar bands (RSB) and the thermal emissive bands (TEB) and an overall assessment of their on-orbit radiometric performance using measurements from instrument on-board calibrators (OBC) as well as regularly scheduled lunar observations. It describes and illustrates changes made and to be made for calibration and data quality improvements. Throughout the mission, all of the OBC have continued to operate and function normally, allowing critical calibration parameters used in the data production systems to be derived and updated. The temperatures of the on-board blackbody (BB) and the cold focal plane assemblies are controlled with excellent stability. Despite large optical throughput degradation discovered shortly after launch in several near and short-wave infrared spectral bands and strong wavelength dependent solar diffuser degradation, the VIIRS overall performance has continued to meet its design requirements. Also discussed in this paper are challenging issues identified and efforts to be made to further enhance the sensor calibration and characterization, thereby maintaining or improving data quality.

Cross calibration of SeaWiFS and MODIS using on-orbit observations of the Moon.

Observations of the Moon provide a primary technique for the on-orbit cross calibration of Earth remote sensing instruments. Monthly lunar observations are major components of the on-orbit calibration strategies of SeaWiFS and MODIS. SeaWiFS has collected more than 132 low phase angle and 59 high phase angle lunar observations over 12 years, Terra MODIS has collected more than 82 scheduled and 297 unscheduled lunar observations over nine years, and Aqua MODIS has collected more than 61 scheduled and 171 unscheduled lunar observations over seven years. The NASA Ocean Biology Processing Group Calibration and Validation Team and the NASA MODIS Characterization Support Team use the USGS RObotic Lunar Observatory (ROLO) photometric model of the Moon to compare these time series of lunar observations over time and varying observing geometries. The cross-calibration results show that Terra MODIS and Aqua MODIS agree, band to band, at the 1%-3% level, while SeaWiFS and either MODIS instrument agree at the 3%-8% level. The combined uncertainties of these comparisons are 1.3% for Terra and Aqua MODIS, 1.4% for SeaWiFS and Terra MODIS, and 1.3% for SeaWiFS and Aqua MODIS. Any residual phase dependence in the ROLO model, based on these observations, is less than 1.7% over the phase angle range of -80° to -6° and +5° to +82°. The lunar cross calibration of SeaWiFS, Terra MODIS, and Aqua MODIS is consistent with the vicarious calibration of ocean color products for these instruments, with the vicarious gains mitigating the calibration biases for the ocean color bands.

Cross calibration of ocean-color bands from moderate resolution imaging spectroradiometer on Terra platform.

Ocean-color applications require maximum uncertainties in blue-wavelength water-leaving radiances in oligotrophic ocean of approximately 5%. Water-leaving radiances from Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra satellite, however, exhibit temporal drift of the order of 15% as well as sensor changes in response versus scan and polarization sensitivity, which cannot be tracked by onboard calibrators. This paper introduces an instrument characterization approach that uses Earth-view data as a calibration source. The approach models the top of the atmosphere signal over ocean that the instrument is expected to measure, including its polarization, with water-leaving radiances coming from another well-calibrated global sensor. The cross calibration allows for significant improvement in derived MODIS-Terra ocean-color products, with largest changes in the blue wavelengths.

Cell cycle dependent antagonistic interactions between paclitaxel and carboplatin in combination therapy.

The combination of carboplatin and paclitaxel is widely used to treat multiple solid tumors including ovarian, lung and breast cancer. Usually these drugs are given simultaneously with little regard to the importance of scheduling to obtain a maximal response. To investigate the importance of sequencing, the human breast Bcap37 and ovarian OV2008 cancer cell lines were exposed to carboplatin and paclitaxel in three different sequences: (1) pretreatment with paclitaxel followed by carboplatin, (2) pretreatment of carboplatin followed by paclitaxel and (3) simultaneous treatment with these two agents. The combination of carboplatin and paclitaxel resulted in antagonistic interactions when tumor cells were exposed to carboplatin prior to paclitaxel or exposed to the two drugs simultaneously, but there was little antagonistic interaction observed when paclitaxel was administered before carboplatin. Biochemical examination revealed that pretreatment or cotreatment of carboplatin inhibited paclitaxel-induced IkappaBalpha degradation and bcl-2 phosphorylation. Further analyses demonstrated that carboplatin could significantly interfere with the cytotoxic effects of paclitaxel on both mitotic arrest and apoptotic cell death unless paclitaxel was administered before carboplatin. These results indicate that the interaction between paclitaxel and carboplatin is highly schedule dependent. The optimal schedule for this combination is sequential exposure of paclitaxel followed by carboplatin.

Combination of gemcitabine antagonizes antitumor activity of paclitaxel through prevention of mitotic arrest and apoptosis.

Paclitaxel, the first member of taxanes, is one of the most active chemotherapeutic agents developed in the last decade for the treatment of advanced breast cancer and many other types of solid tumors. The promising clinical activity of paclitaxel has also promoted considerable interest in combining this drug with other anti-tumor agents. In this study, we assessed the cytotoxic interaction between paclitaxel and gemcitabine administered at various schedules to human breast and ovarian cancer cells. Through a series of in vitro assays including 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays, DNA fragmentation, and flow cytometric analyses, we found that gemcitabine could significantly antagonize the cytotoxic effects of paclitaxel when tumor cells were exposed to the two drugs simultaneously or exposed to gemcitabine before paclitaxel. However, there was little antagonistic interaction observed when paclitaxel was administered before gemcitabine. Further analyses demonstrated that gemcitabine could significantly interfere with the cytotoxic effects of paclitaxel on both mitotic arrest and apoptotic cell death unless paclitaxel is administered before gemcitabine. In addition, biochemical examinations revealed that pretreatment or cotreatment of gemcitabine inhibited paclitaxel-induced IkappaBalpha degradation and bcl-2 phosphorylation that are believed to play critical roles in the signal pathways leading to apoptotic cell death. These results indicate that the interaction between paclitaxel and gemcitabine is highly schedule dependent. Exposure of tumor cells to gemcitabine before paclitaxel or two drugs simultaneously could result in pronounced antagonism. The optimal schedule for this combination might be sequential exposure to paclitaxel followed by gemcitabine.

Expression of telomerase activity, telomerase RNA component and telomerase catalytic subunit gene in lung cancer.

OBJECTIVE: To investigate whether telomerase activity, human telomerase RNA (HTR) and human telomerase reverse transcriptase (HTERT) expression were associated with tumor development in lung cancer and whether telomerase is regulated at gene level or transcriptional level. METHODS: Expression of HTR and HTERT was detected by reverse transcription-polymerase chain reaction (RT-PCR) in 68 human lung cancer and in 68 adjacent-neoplatic lung tissues. And telomerase activity was examined by a quantitative telomeric repeat amplification protocol (TRAP). RESULTS: In 68 lung cancer tissues, telomerase activity, HTR and HTERT were expressed in 79%, 98.5% and 91.2% respectively, whereas all adjacent non-neoplastic lung tissues were telomerase negative. Most normal lung tissues expressed HTR (91.2%) and HTERT was detected in only 7 of 68 non-neoplastic tissues. CONCLUSIONS: The relatively high frequency of telomerase activity in lung cancer whereas the detection of no telomerase activity in normal lung tissues suggested that telomerase may play an important role in tumorigenesis of lung cancer. Compared to HTR, HTERT expression was better associated with telomerase activity with a concordance of 88.9%. Telomerase activity may be regulated at transcription level or translation level.

[Study on the relationship between telomerase gene and telomerase activity in lung cancer tissue].

BACKGROUND: To investigate the relationship between the telomerase activity and telomerase component expression in lung cancer, and to explore whether telomerase activity is regulated at the gene or transcriptional level. METHODS: Expression of the hTR and hTERT were detected in 68 human lung cancer tissues and responsive adjacent non-neoplastic lung tissues by semi-quantitative reverse transcription-polymerase chain reaction. Telomerase activity was detected by telomeric repeat amplification protocol. RESULTS: In 68 lung cancer tissues, the positive rate of the telomerase activity, hTR and hTERT expression were 79.4% (54/68), 98.5% (67/68) and 91.2% (62/68) respectively. Whereas most adjacent non-neoplastic lung tissues expressed hTR (62/68, 91.2%) also, hTERT was detected in only 7 (10.3%) normal lung tissues and no telomerase activity were detected in the 68 non-neoplastic lung cancer tissues. As compared with hTR, hTERT expression was closely related to telomerase activity. The concordance was 89.0% (121/136), whereas the concordance between telomerase and hTR was 43.4% (59/136). CONCLUSIONS: The results suggest that telomerase may play an important role in tumorigenesis of lung cancer. Telomerase activity may be regulated in transcription level or translation level.