Universal characteristics of resonant-tunneling field emission from nanostructured surfaces

We have performed theoretical and experimental studies of field emission from nanostructured semiconductor cathodes. Resonant tunneling through electric-field-induced interface bound states is found to strongly affect the field-emission characteristics. Our analytical theory predicts power-law and Lorentzian-shaped current-voltage curves for resonant-tunneling field emission from three-dimensional substrates and two-dimensional accumulation layers, respectively. These predicted line shapes are observed in field emission characteristics from self-assembled silicon nanostructures. A simple model describes formation of an accumulation layer and of the resonant level in these systems.Comment: 5 pages, 4 figures, RevTex, to appear in J. Appl. Phy

Off-line processing of ERS-1 synthetic aperture radar data with high precision and high throughput

The first European remote sensing satellite ERS-1 will be launched by the European Space Agency (ESA) in 1989. The expected lifetime is two to three years. The spacecraft sensors will primarily support ocean investigations and to a limited extent also land applications. Prime sensor is the Active Microwave Instrumentation (AMI) operating in C-Band either as Synthetic Aperture Radar (SAR) or as Wave-Scatterometer and simultaneously as Wind-Scatterometer. In Europe there will be two distinct types of processing for ERS-1 SAR data, Fast Delivery Processing and Precision Processing. Fast Delivery Proceessing will be carried out at the ground stations and up to three Fast Delivery products per pass will be delivered to end users via satellite within three hours after data acquisition. Precision Processing will be carried out in delayed time and products will not be generated until several days or weeks after data acquisition. However, a wide range of products will be generated by several Processing and Archiving Facilities (PAF) in a joint effort coordinated by ESA. The German Remote Sensing Data Center (Deutsches Fernerkundungsdatenzentrum DFD) will develop and operate one of these facilities. The related activities include the acquisition, processing and evaluation of such data for scientific, public and commercial users. Based on this experience the German Remote Sensing Data Center is presently performing a Phase-B study regarding the development of a SAR processor for ERS-1. The conceptual design of this processing facility is briefly outlined

Measuring Evapotranspiration of five Alley Cropping systems in Germany using the Eddy-Covariance- and Bowen-Ratio Energy-Balance methods

Measuring evapotranspiration (ET) of heterogeneous ecosystems using methods like the eddy-covariance- (ECEB) and Bowen-Ratio energy-balance (BREB) methods is challenging due to their restrictions to horizontally homogeneous terrain and steady state conditions. The unfavorable ambient conditions lead to a site-specific non-closure of the energy-balance, which is a balance between the incoming net radiation and the ground-, latent- and sensible heat fluxes. Thus, an underestimation of measured heat fluxes leads to an overestimation of the latent heat fluxes inferred from the ECEB method. The aim of our study is to 1) quantify the site-specific non-closure of the energy-balance and 2) characterize the performance of both methods, compared to direct eddy-covariance measurements using a high-frequency infra-red gas analyzer (LI-7200, Licor Inc.). To assess continuous ET rates on a 30-minute time scale we installed a combined ECEB and BREB system at five alley cropping and five agricultural reference sites across Germany. For time periods of four weeks, we performed direct eddy covariance flux measurements for H2O and CO2 over one crop- and one grassland alley cropping- and their respective reference systems during the growing season of 2016. We found a non-closure between 21 and 26 % for all sites, with the residual energy being highest during the morning and lowest in the afternoon. Related to that the energy-balance ratio (EBR), i.e. the ratio between the turbulent heat fluxes and available energy, was below one in the morning hours and increased slightly during the day up to 1.8, until the EBR decreased sharply after sunset. The EBR correlated to the daily cycle of solar radiation, the main driver of turbulent fluxes. Corresponding, we found an increasing EBR with increasing friction velocity, indicating, that the energy-balance closure improves under turbulent condition. Further our analysis reveal that turbulent fluxes estimated by the BREB method compared well with direct eddy-covariance measurements. An accuracy improvement was found with increasing sensor distance. We conclude, when calculating ET rates on a 30-minute time scale using the ECEB method the site-specific non-closure should be assessed beforehand by eddy-covariance. In the current study, ignoring the non-closure would have lead to an overestimation of the ET rates of about 25 % for the ECEB method

Wartość diagnostyczna CA125, HE4, ROMA oraz modelu regresji logistycznej w diagnistyce guzów miednicy mniejszej – doświadczenia własne

Objectives: The aim of this study was to compare and evaluate the quality of CA125, HE4, logistic regression model based on CA125 and HE4, and ROMA algorithm in preoperational differential diagnostics of the ovarian tumors. Material and methods: To the study 110 patients enrolled. Based on histopatological examination of removed tumors, they were divided into study group (56 cancer patients) and control one (nonmalignant 54 patients). Serum CA125 and HE4 concentrations were measured following a standard procedure. Results: A commonly accepted referential value for CA125 is 35 IU/ml. In our study, this cut-off value yielded very low sensitivity and specificity results (85.2% and 63.6%, respectively). When we adopted HE4 normal value to be 140 pM,the sensitivity and specificity obtained in the investigated population was 68.5% and 94.6%, respectively. When the cut-off value for HE4 was adopted as 74 pM, the sensitivity improved considerably (88.9%), but specificity decreased to 85.7%. In case of CA125 when we adopted Ca125 normal value to be 77 IU/ml, the sensitivity and specificity obtained in the investigated population was 81.5% and 83.6%, respectively. In analysis based on combination of biomarkers, the highest sensitivity was obtained for the logistic regression model based on CA125 and HE4 (89.5%). A little bit lower sensitivity was achieved for HE4 used as a single diagnostic test (88.9%). The highest specificity was observed for ROMA algorithm (94.5%). This means that ROMA algorithm is the best diagnostic tool to differentiate between the malignant and non-malignant ovarian tumors. Conclusions: 1. ROMA algorithm yielded the highest specificity and slightly lower sensitivity in the case of differential diagnosis between malignant and non-malignant ovarian tumors. Therefore, it should become a basic tool in the ovarian tumors diagnosis prior to a surgery. 2. HE4 as a single diagnostic test (based on one marker) was found to be better suited to the ovarian tumor differential diagnosis than CA125 test. 3. Combined test, based on double marker analysis, should be applied and then the risk of the ovarian cancer should be calculated. This approach is more effective than single marker analysis.Cel pracy: Celem niniejszego badania było porównanie i ocena wartości CA125, HE4, modelu regresji logistycznej oraz algorytmu ROMA w przedoperacyjnej diagnostyce różnicowej guzów przydatków. Materiał i metody: Do badania włączono 110 pacjentki, które na podstawie wyniku badania histopatologicznego usuniętych guzów podzielono na grupę badaną (56 pacjentek z nowotworami złośliwymi) i grupę kontrolną (54 pacjentek ze zmianami niezłośliwymi). Oznaczenie osoczowych stężeń CA125 oraz HE4 wykonano zgodnie z standardową procedurą. Wyniki: Powszechnie uznaną wartością graniczną dla CA125 jest 35 IU/ml. W naszym badaniu, przyjęcie tej wartości punktu odcięcia zaowocowało niskimi wartościami czułości i swoistości – odpowiednio 85,2% oraz 63,6%. Wyjściowo uznaliśmy wartość 140 pM jako punkt odcięcia (wartość sugerowana przez producenta). Dla takiego punktu odcięcia, czułość i swoistość osiągnęły odpowiednio wartość 68,5% i 94,6%. Gdy wartość punktu odcięcia dla HE4 została zmieniona na 74 pM, czułość testu wzrosła do 88,9% a swoistość zmniejszyła się do 85.7%. W przypadku CA125 zmiana wartości punktu odcięcia na 77 IU/ml spowodowała spadek czułości do 81,5% przy jednoczesnym wzroście swoistości do 83,6%. W analizach obejmujących jednocześnie obydwa markery (CA 125 i HE4), model oparty na regresji logistycznej osiągnął najwyższą czułość (89,5%). Niewiele mniejszą wartość czułości osiągnął test oparty na oznaczeniu HE4 (88,9%). Natomiast najwyższą wartość swoistości osiągnął algorytm ROMA (94,5%). Oznacza to że algorytm ROMA jest najlepszym narzędziem diagnostycznym w różnicowaniu złośliwych i niezłośliwych guzów jajnika. Wnioski: 1. Algorytm ROMA osiągnął najwyższą wartość swoistości i niewiele niższą wartość czułości jako narzędzie diagnostyczne w różnicowaniu złośliwych od niezłośliwych guzów jajnika. Dlatego powinien zostać podstawowym narzędziem diagnostycznym przed planowanym leczeniem chirurgicznym. 2. HE4 jako pojedynczy test diagnostyczny osiągnął wyższe wartości czułości i swoistości w porównaniu z CA 125. 3. Jednoczesne oznaczanie dwóch markerów (CA 125 i HE4) oraz obliczanie ryzyka wystąpienia nowotworu złośliwego jest zalecanym postępowaniem u pacjentek z guzami przydatków. Analizy oparte na dwóch markerach są bardziej efektywne niż analizy oparte na pojedynczych markerach

A non-homogeneous semi-Markov model for interval censoring

Previous approaches to modelling interval-censored data have often relied on assumptions of homogeneity in the sense that the censoring mechanism, the underlying distribution of occurrence times, or both, are assumed to be time-invariant. In this work, we introduce a model which allows for non-homogeneous behaviour in both cases. In particular, we outline a censoring mechanism based on semi-Markov processes in which interval generation is assumed to be time-dependent and we propose a Markov point process model for the underlying occurrence time distribution. We prove the existence of this process and derive the conditional distribution of the occurrence times given the intervals. We provide a framework within which the process can be accurately modelled, and subsequently compare our model to homogeneous approaches by way of a parametric example

A non-homogeneous Semi-Markov model for Interval Censoring

Previous approaches to modelling interval-censored data have often relied on assumptions of homogeneity in the sense that the censoring mechanism, the underlying distribution of occurrence times, or both, are assumed to be time-invariant. In this work, we introduce a model which allows for non-homogeneous behaviour in both cases. In particular, we outline a censoring mechanism based on semi-Markov processes in which interval generation is assumed to be time-dependent and we propose a Markov point process model for the underlying occurrence time distribution. We prove the existence of this process and derive the conditional distribution of the occurrence times given the intervals. We provide a framework within which the process can be accurately modelled, and subsequently compare our model to homogeneous approaches by way of a parametric example.Comment: 21 pages, 4 figure

Pegylated liposomal doxorubicin in ovarian cancer treatment

Summary Ovarian cancer treatment after cytoreductive surgery is based solely on chemotherapy. Pegylated liposomal doxorubicin (PLD) is a cytotoxic agent of verified efficacy in the treatment of ovarian cancer and is may be used in the first and the following lines of chemotherapy. In the first-line ovarian cancer treatment the combination of PLD with carboplatin assures a prolonged interval to progression and produces less toxicity when compared to carboplatin with paclitaxel schedule. Calypso trial has also revealed that in platinum-sensitive recurrent ovarian cancer PLD with carboplatin shows better anticancer efficiency in comparison to combination carboplatin with paclitaxel and its toxicity profile is quite unique. Namely, PLD does not cause hematological complications, neuropathy, balding and hair loss that are characteristic of other chemotherapeutics applied in ovarian cancer treatment. Palmar-plantar erythrodysesthesia, a typical and commonly noted adverse event, rarely occurs when the dosage is 40mg/m2 iv. Thus, PLD ought to be the drug of choice in recurrent ovarian cancer treatment, both platinum-sensitive and platinum-insensitive one. In case of partially platinum-sensitive ovarian cancer PLD allows for a longer withoutplatinum period what in turn allows for yet another treatment with platinum, and helps achieve a prolonged interval to progression and progression-free survival time

Obwodowa neuropatia indukowana chemioterapią — epidemiologia i patogeneza

Chemotherapy-induced peripheral neuropathy (CIPN) is one of the most important neurologic complications experienced by patients receiving chemotherapy. The neuropathy often interferes with daily activities and exercise leading to severe impairment of the patient’s quality of life (QoL). The evolution of most CIPNs is characterized by a gradual onset of signs/symptoms, beginning in the lower limbs and advancing proximally into a bilateral stocking and glove distribution. Patients often complain of numbness, tingling and pain in the affected areas. The symptoms become aggravated with repeated cycles of chemotherapy. When the offending agent is withheld, the symptoms generally abate, but relief is not guaranteed. The consequences of delay or discontinuation of treatment may affect overall patient survival.Obwodowa neuropatia indukowana chemioterapią jest jednym z najważniejszych powikłań neurologicznych u pacjentek jej podanych, często zakłócając codzienne aktywności i upośledzając jakość życia a jej objawy pogarszają się przy powtarzanych cyklach chemioterapii. Omówiono stopnie nasilenia neuropatii (Tabela I), jej epidemiologię (szacuje się że doświadcza jej 30% do 55% pacjentów otrzymujących chemioterapię). Jej nasilenie i jakość zależy od czynników osobistego ryzyka (wcześniej istniejące neuropatie, choroby towarzyszące i operacje) i od stosowanego leku (jego typu, sposobu podawania, dawki itp). Omówiono efekty podawania rożnych czynnikowa chemioterapii (docetakselu, winkrystyny, iksabepilonu, oksaliplatyny, cisplatyny, talodomidu, lenalidomidu, bortezomibu), różnice wrażliwości na neuropatię wynikające z polimorfizmu genowego, wieku pacjenta

Semaphorin 3A (SEMA3A), protocadherin 9 (PCdh9), and S100 calcium binding protein A3 (S100A3) as potential biomarkers of carcinogenesis and chemoresistance of different neoplasms, including ovarian cancer — review of literature

Ovarian cancer is the fifth leading cause of cancer-related deaths in women. Its high mortality rate results from lack of adequate and sensitive methods allowing for the detection of the early stages of the disease, as well as low efficiency of the treatment, caused by the cytotoxic drug resistance of cancer cells. Unfortunately, tumours are able to develop new pathways and protective mechanisms that allow them to survive toxic conditions of chemotherapy. Therefore, intensive search for new genes and proteins involved in resistance to cytotoxic drugs is still needed, especially from a clinical point of view. The article presents an overview of the available literature on the role of semaphorin 3A (SEMA3A), protocadherin 9 (PCDH9), and S100 calcium binding protein A3 (S100A3) in carcinogenesis and chemoresistance of various tumors including ovarian cancer. As it turns out, the role of described genes/proteins is not limited only to their native biological activity but they function also as an oncogenic or suppressor factors in the tumor development. Moreover, they can also play an important role in development of drug resistance, as it was shown in ovarian cancer cell lines